Internal Medicine Practice Questions — USMLE Step 2 CK — Page 51

Question 1001Question →

A 63-year-old man with a history of metastatic non-small cell lung cancer is brought to the emergency department by his family. Over the past week, he has experienced progressively worsening, severe mid-thoracic back pain that is exacerbated by coughing. This morning, he was unable to stand due to profound weakness in his legs and reports that he has not been able to urinate for the past $12$ hours. On physical examination, his temperature is $36.9^\circ\text{C}$ ( $98.4^\circ\text{F}$ ), blood pressure is $142/88\text{ mmHg}$ , and heart rate is $98/\text{min}$ . Neurologic examination reveals $2/5$ motor strength in bilateral lower extremities, hyperactive patellar reflexes, positive Babinski signs bilaterally, and diminished sensation to pinprick below the level of the umbilicus. A post-void residual volume measured by bladder ultrasound is $750\text{ mL}$ . Suspecting malignant epidural spinal cord compression, arrange the following management steps in the most appropriate sequential order.

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Answer

The correct sequential order for managing suspected malignant epidural spinal cord compression with neurologic deficits is to first administer high-dose intravenous dexamethasone, followed by an urgent MRI of the entire spine, then obtain specialty consultation with neurosurgery and radiation oncology, and finally provide definitive targeted therapy.

The correct sequence prioritizes immediate neurologic preservation over diagnostic confirmation. High-dose steroids reduce edema and must be given first when deficits are present. This is followed by an MRI to define the anatomy, which is then used by consulting specialists to plan and execute definitive surgical or radiation therapy.

Step-by-Step Solution

1

Evaluate the clinical presentation.

The patient demonstrates severe back pain, lower extremity weakness, upper motor neuron signs (hyperreflexia, positive Babinski), and autonomic dysfunction (urinary retention) in the setting of metastatic lung cancer.

These findings are highly characteristic of a life-threatening oncologic emergency: malignant epidural spinal cord compression (ESCC).

2

Determine the most critical immediate intervention.

High-dose intravenous dexamethasone must be administered immediately.

When objective neurologic deficits are present, early corticosteroid administration reduces vasogenic edema and is the most important factor in preventing irreversible paralysis. It must be given prior to diagnostic imaging.

3

Identify the definitive diagnostic step.

An urgent MRI of the entire spine is obtained.

Imaging is required to confirm the diagnosis and map the extent of the disease, but it must not delay the administration of steroids.

4

Determine the sequence of definitive management.

Specialist consultation is obtained to plan and execute targeted therapy (surgery or radiation).

Specialists require the MRI results to safely determine the most appropriate definitive intervention.

Key Concept

In patients with suspected malignant epidural spinal cord compression presenting with neurologic deficits, empiric high-dose intravenous glucocorticoids must be administered immediately prior to confirmatory imaging to preserve neurologic function.

Estimated Time:1m 30s

Question 1002Question →

Match each atypical clinical presentation of a complex hematologic or coagulopathic disorder to the most appropriate and highly specific targeted management strategy.

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Answer

The correct matches align each pathophysiologic crisis with its targeted intervention: Acquired Hemophilia A requires bypassing agents; HIT requires a direct thrombin inhibitor; TTP requires plasma exchange; Obstetric APS without prior thrombosis requires prophylactic LMWH and aspirin; Warfarin necrosis requires Vitamin K reversal and heparin.

Each clinical scenario describes a specific, high-acuity hematologic disorder with a definitive, pathophysiology-driven treatment. Acquired Hemophilia A requires bypassing agents because autoantibodies neutralize standard factor replacement. HIT requires a non-heparin anticoagulant because any heparin fuels the immune response. TTP requires plasma exchange to remove ADAMTS13 autoantibodies. Obstetric APS requires prophylactic anticoagulation to prevent placental thrombosis. Warfarin necrosis requires immediate reversal of the vitamin K antagonist and therapeutic heparinization.

Step-by-Step Solution

1

Analyze the first scenario featuring isolated prolonged aPTT that does not correct with a mixing study in an older adult with sudden bleeding.

Diagnosis is Acquired Hemophilia A (Factor VIII inhibitor).

The mixing study failure confirms an autoantibody inhibitor rather than a factor deficiency. Treatment requires bypassing the intrinsic pathway using rFVIIa.

2

Analyze the second scenario featuring heparin exposure, a greater than 50% platelet drop, and a necrotic skin lesion.

Diagnosis is Heparin-Induced Thrombocytopenia (HIT).

Antibodies to PF4-heparin complexes cause widespread platelet activation. Heparin must be stopped and a direct thrombin inhibitor started to prevent further thrombosis.

3

Analyze the third scenario featuring fever, confusion, severe thrombocytopenia, MAHA, and a normal coagulation panel.

Diagnosis is Thrombotic Thrombocytopenic Purpura (TTP).

ADAMTS13 deficiency leads to uncleaved von Willebrand factor multimers and microthrombi. Plasma exchange removes the offending autoantibody and replaces ADAMTS13.

4

Analyze the fourth scenario featuring a pregnant patient with recurrent miscarriages, positive antiphospholipid antibodies, and no history of DVT.

Diagnosis is obstetric Antiphospholipid Syndrome (APS).

In the absence of a prior unprovoked thrombosis, the evidence-based treatment to prevent fetal loss is prophylactic-dose LMWH and low-dose aspirin.

5

Analyze the fifth scenario featuring warfarin monotherapy initiation followed rapidly by skin necrosis.

Diagnosis is Warfarin-induced skin necrosis.

The rapid depletion of Protein C relative to procoagulant factors causes microvascular thrombosis. This emergency requires immediate warfarin reversal and administration of heparin.

Key Concept

Management of life-threatening hematologic and coagulopathic emergencies requires precise identification of the underlying pathophysiology (e.g., autoantibody inhibitor vs. enzyme deficiency) to select the correct targeted therapy.

Question 1003Question →

A 34-year-old woman presents to the outpatient department due to left-sided chest pain and shortness of breath for the past 3 days. The chest pain is sharp and noticeably worsens when she takes a deep breath or coughs. She also reports feeling persistently fatigued and sad for the past month. Her medical history is significant for systemic lupus erythematosus (SLE) and bipolar disorder. Her current daily medications include hydroxychloroquine, prednisone 5 mg, and quetiapine. Her temperature is 37.8°C (100.0°F), blood pressure is 120/78 mmHg, and heart rate is 88/min. Cardiopulmonary examination reveals a pleural friction rub on the left side, with no murmurs, gallops, or jugular venous distention. A chest radiograph demonstrates a small left-sided pleural effusion without any pulmonary infiltrates. An electrocardiogram is unremarkable. Which of the following is the most appropriate next step in the management of this patient?

Administer intravenous furosemide and topical nitroglycerin

Administer the live-attenuated intranasal influenza vaccine

Prescribe an oral nonsteroidal anti-inflammatory drug

Discontinue quetiapine and start fluoxetine monotherapy

Initiate empiric therapy with oral levofloxacin

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Answer: Prescribe an oral nonsteroidal anti-inflammatory drug

Answer

Prescribe an oral nonsteroidal anti-inflammatory drug

The correct course of action is to prescribe an oral nonsteroidal anti-inflammatory drug. This patient is presenting with acute serositis (specifically pleuritis), which is a common hallmark of systemic lupus erythematosus (SLE) flares. It classically presents with pleuritic chest pain, a pleural friction rub on auscultation, and potentially a small, exudative pleural effusion. For mild to moderate SLE serositis that is not organ-threatening, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, or indomethacin are the standard and most appropriate first-line therapy.

Step-by-Step Solution

1

Evaluate the clinical presentation and physical exam findings.

The patient has sharp, pleuritic chest pain, a pleural friction rub, and a small pleural effusion without pulmonary infiltrates.

Identifying these classic signs helps localize the pathology to the pleura.

2

Correlate the findings with the patient's medical history.

The presentation is consistent with acute lupus serositis (pleuritis), a common manifestation of an SLE flare.

SLE frequently causes inflammation of serosal surfaces, including the pleura and pericardium.

3

Determine the most appropriate initial management for this specific condition.

An oral nonsteroidal anti-inflammatory drug (NSAID) is the standard initial therapy.

Mild serositis in SLE responds well to NSAIDs. If symptoms were severe or refractory, increasing the systemic corticosteroid dose would be the next step.

Key Concept

Mild to moderate serositis in systemic lupus erythematosus is typically treated initially with nonsteroidal anti-inflammatory drugs (NSAIDs).

Question 1004Question →

Match each patient's clinical presentation and laboratory findings of hyponatremia with the most appropriate targeted initial therapeutic intervention.

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Answer

Proper therapy requires matching severe neurological symptoms to immediate hypertonic saline administration, and matching the remaining asymptomatic cases to targeted fluid management based on volume status (hypovolemic requires normal saline, euvolemic requires fluid restriction, and hypervolemic requires diuresis).

Matching the correct fluid therapy requires first ruling out severe symptoms (which necessitate hypertonic saline to prevent herniation) and then assessing volume status. Hypovolemic patients have total body sodium and water depletion, requiring isotonic saline volume expansion to shut off non-osmotic ADH. Euvolemic patients (often SIADH) have excess free water, which is treated with fluid restriction. Hypervolemic patients have profound sodium avidity but even greater water retention, treated effectively with loop diuretics.

Step-by-Step Solution

1

Assess the severity of neurological symptoms in each clinical vignette.

The 78-year-old woman has severe symptoms (seizures) and requires immediate hypertonic (3%) saline to reverse cerebral edema.

Symptomatic severe hyponatremia is a neurological emergency that overrides the standard volume status-based algorithm.

2

Evaluate the clinical volume status of the remaining mildly symptomatic or asymptomatic patients.

The 42-year-old woman is hypovolemic (hypotensive, tachycardic). The 66-year-old man is hypervolemic (JVD, crackles). The 54-year-old man is euvolemic (normal turgor, moist mucous membranes).

In the absence of severe symptoms, the underlying volume status dictates the pathophysiology of ADH release and the targeted intervention.

3

Assign the appropriate therapeutic intervention to each distinct volume state.

Hypovolemia requires isotonic (0.9%) saline to restore perfusion. Hypervolemia requires diuresis (furosemide). Euvolemia (SIADH) requires fluid restriction.

Directly addressing the physiological trigger for ADH secretion (or restricting free water intake when ADH is inappropriately secreted) safely normalizes the serum sodium over time.

Key Concept

Management of hyponatremia is strictly determined by two main factors: the presence of severe neurological symptoms (requiring immediate 3% hypertonic saline) and the patient's clinical volume status.

Question 1005Question →

A 68-year-old man with a history of atrial fibrillation is brought to the emergency department after vomiting large amounts of bright red blood. He takes warfarin daily. On presentation, he appears pale and lethargic. His temperature is 37.1°C (98.8°F), blood pressure is 88/56 mm Hg, and heart rate is 118/min. Physical examination reveals delayed capillary refill and cool extremities. Laboratory studies show a hemoglobin of 8.2 g/dL and an International Normalized Ratio (INR) of 8.4. Intravenous fluid resuscitation with normal saline is initiated. Which of the following is the most appropriate next step in management?

Administer intravenous vitamin K only

Administer protamine sulfate

Administer prothrombin complex concentrate and intravenous vitamin K

Administer fresh frozen plasma without vitamin K

Administer broad-spectrum intravenous antibiotics

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Answer: Administer prothrombin complex concentrate and intravenous vitamin K

Answer

The most appropriate next step is to administer prothrombin complex concentrate and intravenous vitamin K.

Warfarin inhibits the enzyme vitamin K epoxide reductase, which prevents the activation of vitamin K-dependent clotting factors (II, VII, IX, and X). In the setting of severe, life-threatening bleeding with an elevated INR, immediate and sustained reversal of anticoagulation is mandatory. Prothrombin complex concentrate (PCC) contains concentrated factors II, VII, IX, and X, providing rapid correction of the coagulopathy with minimal volume load (unlike fresh frozen plasma). Intravenous vitamin K must be administered concurrently to provide the substrate needed for the liver to synthesize new endogenous clotting factors, which prevents rebound coagulopathy once the administered PCC degrades.

Step-by-Step Solution

1

Identify the clinical emergency and patient stability.

The patient has severe, life-threatening gastrointestinal hemorrhage and is hemodynamically unstable (hypotensive and tachycardic).

Determines the urgency of intervention; conservative or slow-acting therapies are insufficient.

2

Determine the underlying etiology of the coagulopathy.

The patient is on warfarin and has a markedly supratherapeutic INR of 8.4.

Guides the choice of a specific pharmacologic reversal agent.

3

Select the optimal targeted therapy for rapid reversal.

Prothrombin complex concentrate (PCC) is selected for immediate factor replacement, combined with intravenous vitamin K for sustained effect.

PCC acts within minutes and has less volume load than fresh frozen plasma, making it the standard of care for severe warfarin-associated bleeding.

Key Concept

Severe, life-threatening bleeding associated with warfarin toxicity requires immediate reversal with prothrombin complex concentrate (PCC) and intravenous vitamin K.

Question 1006Question →

Match the following common outpatient clinical presentations to their most appropriate first-line oral pharmacological therapy.

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Answer

Uncomplicated cystitis matches with nitrofurantoin. The purulent skin abscess matches with trimethoprim-sulfamethoxazole. Streptococcal pharyngitis matches with amoxicillin. Early localized Lyme disease matches with doxycycline.

Each clinical presentation aligns perfectly with a specific first-line antibiotic based on primary care guidelines. Nitrofurantoin treats uncomplicated cystitis effectively. Trimethoprim-sulfamethoxazole is appropriately used for CA-MRSA in purulent abscesses. Amoxicillin successfully treats Group A strep pharyngitis. Doxycycline is the gold standard for early localized Lyme disease.

Step-by-Step Solution

1

Identify the underlying infectious diagnosis for each clinical vignette.

The presentations correspond to uncomplicated cystitis, purulent skin abscess (suspected MRSA), streptococcal pharyngitis, and early localized Lyme disease.

Accurate clinical diagnosis is required before selecting empirical antimicrobial therapy.

2

Assign the first-line oral antimicrobial agent for each identified condition based on standard guidelines.

Nitrofurantoin is assigned to cystitis, trimethoprim-sulfamethoxazole to the abscess, amoxicillin to pharyngitis, and doxycycline to Lyme disease.

Following evidence-based guidelines ensures optimal patient outcomes and promotes antibiotic stewardship.

Key Concept

First-line empiric antimicrobial therapy for common outpatient infections

Question 1007Question →

Evaluate the following clinical presentations of immunocompromised patients with opportunistic infections. Match each clinical scenario with the most appropriate initial targeted pharmacotherapy.

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Answer

The correct matches require correlating the clinical and pathologic description with the pathogen: Pneumocystis jirovecii in a G6PD-deficient patient requires intravenous pentamidine; Tuberculous meningitis requires RIPE plus dexamethasone; Invasive aspergillosis requires intravenous voriconazole; Severe disseminated histoplasmosis requires liposomal amphotericin B; and Central nervous system nocardiosis requires high-dose trimethoprim-sulfamethoxazole.

Each pair correctly matches a specific opportunistic pathogen, identified by definitive clinical and diagnostic findings, with its first-line evidence-based pharmacotherapy, specifically taking into account critical patient-level constraints such as immune status, infection severity, and genetic enzyme deficiencies.

Step-by-Step Solution

1

Identify the causal opportunistic pathogen for each clinical scenario based on pathognomonic historical, radiographic, and pathologic clues.

Scenario 1: Pneumocystis jirovecii. Scenario 2: Mycobacterium tuberculosis. Scenario 3: Aspergillus fumigatus. Scenario 4: Histoplasma capsulatum. Scenario 5: Nocardia species.

Accurate pathogen identification is the prerequisite for selecting targeted antimicrobial therapy.

2

Determine the standard first-line targeted therapy for each identified pathogen, modifying the choice based on strict patient-specific contraindications or required adjunctive therapies.

PCP standard therapy (TMP-SMX) is contraindicated by G6PD deficiency, necessitating IV pentamidine. TB meningitis strictly requires adjunctive corticosteroids alongside RIPE therapy to prevent fatal inflammation.

Rote memorization of first-line agents fails in complex clinical scenarios where host factors (e.g., enzyme deficiencies, critical CNS inflammation) dictate life-saving modifications to the standard regimen.

Key Concept

Diagnosis and targeted pharmacotherapy of complex opportunistic infections in immunocompromised hosts, requiring strict adherence to patient-specific contraindications.

Estimated Time:3m 0s

Question 1008Question →

A 55-year-old man with poorly controlled type 2 diabetes mellitus is evaluated in the hospital on day 4 of admission for a severe diabetic foot infection. He initially presented with a deep, purulent ulcer on the plantar aspect of his right foot surrounded by extensive cellulitis. On admission, empiric therapy was initiated with intravenous vancomycin and piperacillin-tazobactam, and he subsequently underwent surgical debridement of necrotic tissue. Today, his temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $128/78\text{ mm Hg}$ , and pulse is $78\text{/min}$ . The wound appears clean with developing granulation tissue. Deep tissue cultures obtained during surgery yield heavy growth of Staphylococcus aureus. Antimicrobial susceptibility testing demonstrates resistance to penicillin and susceptibility to oxacillin, cefazolin, and vancomycin. Which of the following is the most appropriate next step in pharmacotherapy?

Discontinue current antibiotics and initiate intravenous cefazolin

Discontinue piperacillin-tazobactam and continue intravenous vancomycin

Discontinue vancomycin and continue intravenous piperacillin-tazobactam

Continue both intravenous vancomycin and piperacillin-tazobactam

Discontinue current antibiotics and initiate intravenous daptomycin

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Answer: Discontinue current antibiotics and initiate intravenous cefazolin

Answer

Discontinue current antibiotics and initiate intravenous cefazolin

The patient's cultures grew methicillin-susceptible Staphylococcus aureus (MSSA). For severe MSSA infections, such as osteomyelitis or deep tissue infections associated with diabetic foot ulcers, antistaphylococcal beta-lactams (e.g., cefazolin, nafcillin, oxacillin) are the treatment of choice. They have superior bactericidal activity and are associated with lower mortality and treatment failure rates compared to vancomycin. Therefore, the most appropriate step is to discontinue the broad-spectrum empiric regimen and initiate targeted therapy with intravenous cefazolin.

Step-by-Step Solution

1

Interpret the culture and susceptibility results

The pathogen is methicillin-susceptible Staphylococcus aureus (MSSA), as indicated by susceptibility to oxacillin and cefazolin.

Identifying the specific organism and its resistance profile is essential for transitioning from empiric to targeted therapy.

2

Evaluate the current empiric antibiotic regimen

The patient is on vancomycin (MRSA coverage) and piperacillin-tazobactam (broad Gram-negative and anaerobic coverage).

Empiric therapy must be narrowed to prevent the development of resistance and minimize adverse drug events.

3

Select the optimal targeted therapy for MSSA

Intravenous cefazolin is chosen over vancomycin and piperacillin-tazobactam.

Antistaphylococcal beta-lactams (e.g., cefazolin, nafcillin, oxacillin) are superior to vancomycin for MSSA infections, offering faster bacterial clearance and lower mortality.

Key Concept

Methicillin-susceptible Staphylococcus aureus (MSSA) infections should be treated with narrow-spectrum antistaphylococcal beta-lactams (e.g., cefazolin, nafcillin, oxacillin) rather than vancomycin or broader-spectrum beta-lactams like piperacillin-tazobactam, in accordance with antimicrobial stewardship.

Question 1009Question →

Match the following complex nephrologic and acid-base clinical presentations with their most appropriate specific therapeutic interventions.

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Answer

The correct pairings match gastrointestinal losses to oral potassium and alkali replacement; Type 1 RTA to alkali therapy; Type 4 RTA to loop diuretics or fludrocortisone; refractory heart failure hyponatremia to vaptans; and symptomatic severe SIADH to 3% hypertonic saline.

The correct matches appropriately pair the underlying pathophysiology of distinct nephrologic and acid-base disturbances with their specific targeted interventions. Identifying whether a non-anion gap metabolic acidosis is renal or gastrointestinal in origin relies on the Urine Anion Gap (

\text{UAG} = Na^+ + K^+ - Cl^-

). The UAG estimates urinary ammonium (

NH_4^+

) excretion. A negative UAG points to extrarenal GI losses requiring oral replacement. A positive UAG with hypokalemia and a urine pH

> 5.5

indicates Type 1 RTA, treated with alkali. A positive UAG with hyperkalemia indicates Type 4 RTA, treated by lowering potassium. For hyponatremia, refractory hypervolemic cases in heart failure are an indication for vaptans, whereas severe symptomatic cases (e.g., seizures) always require immediate

3\%

hypertonic saline.

Step-by-Step Solution

1

Analyze the acid-base parameters and urine anion gap (UAG) for the first three patients.

Patient 1 has a negative UAG (GI loss). Patient 2 has a positive UAG, hypokalemia, and urine pH > 5.5 (Type 1 RTA). Patient 3 has a positive UAG, hyperkalemia, and urine pH < 5.5 (Type 4 RTA).

UAG estimates urinary ammonium excretion; a negative UAG indicates an intact renal response (extrarenal cause), while a positive UAG indicates a renal acidification defect (RTA).

2

Select the appropriate targeted intervention for each acid-base disorder.

GI losses require oral replacement. Type 1 RTA requires alkali to correct the distal defect. Type 4 RTA requires potassium-lowering agents like fludrocortisone or loop diuretics.

Therapies must strictly target the specific pathophysiological defect causing the acidosis.

3

Evaluate the volume status and symptom severity for the patients with hyponatremia.

Patient 4 has refractory hypervolemic hyponatremia (heart failure). Patient 5 has euvolemic hyponatremia (SIADH) with severe neurologic symptoms (seizures).

Hyponatremia management is dictated first by symptom severity (seizures require 3% saline) and then by volume status.

4

Match the hyponatremia presentations to their interventions.

Patient 4 matches with vasopressin-2 receptor antagonists (tolvaptan). Patient 5 matches with immediate 3% hypertonic saline.

Vaptans promote aquaresis in volume-overloaded states, while hypertonic saline rapidly reverses life-threatening cerebral edema.

Key Concept

Differentiation of non-anion gap metabolic acidoses using the urine anion gap and serum potassium, alongside targeted management of euvolemic and hypervolemic hyponatremia based on symptom severity.

Estimated Time:2m 30s

Question 1010Question →

An emergency department evaluation is requested for a $42$ -year-old man who reports severe, diffuse abdominal pain that consistently begins $30\text{ minutes}$ after meals over the past $4\text{ weeks}$ . He also reports a $6\text{-kg}$ ( $13\text{-lb}$ ) weight loss during this period, diffuse muscle aches, and intermittent fevers. Two days ago, the patient developed difficulty lifting his right foot while walking. His temperature is $38.1^\circ\text{C}$ ( $100.6^\circ\text{F}$ ) and blood pressure is $168/98\text{ mmHg}$ . Physical examination shows a mottled, purplish, net-like rash on the lower extremities. Neurologic examination demonstrates $2/5$ motor strength in right foot dorsiflexion and decreased pinprick sensation over the right lateral calf.

Laboratory studies are as follows:

Laboratory Test	Result
Hemoglobin	$10.8\text{ g/dL}$
Leukocyte count	$12,500/\text{mm}^3$
Platelet count	$410,000/\text{mm}^3$
Blood urea nitrogen	$32\text{ mg/dL}$
Serum creatinine	$1.9\text{ mg/dL}$
Erythrocyte sedimentation rate	$78\text{ mm/h}$
Hepatitis B surface antigen	Positive

Urinalysis reveals $1+$ protein, $0-2$ red blood cells/hpf, and no cellular casts.

Which of the following is the most appropriate next step in diagnosis?

Mesenteric and renal angiography

Percutaneous renal biopsy

Testing for antineutrophil cytoplasmic antibodies

Electromyography and nerve conduction studies

Colonoscopy with mucosal biopsy

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Answer: Mesenteric and renal angiography

Answer

The correct answer is mesenteric and renal angiography, which is the preferred diagnostic modality for polyarteritis nodosa (PAN) presenting with intra-abdominal and renal involvement.

The correct next step is mesenteric and renal angiography. This patient's clinical presentation—postprandial abdominal pain (intestinal angina), mononeuritis multiplex (foot drop), livedo reticularis, new-onset hypertension, and acute kidney injury—in the setting of chronic Hepatitis B infection is highly characteristic of polyarteritis nodosa (PAN). PAN is a systemic necrotizing vasculitis that primarily targets medium-sized muscular arteries. When intra-abdominal or renal involvement is prominent, mesenteric and renal angiography is the preferred diagnostic test. It classically reveals multiple microaneurysms and segmental narrowing (often described as a 'string of pearls' appearance) of the medium-sized arteries. Angiography provides a high diagnostic yield while entirely avoiding the significant bleeding risks associated with deep tissue biopsies.

Step-by-Step Solution

1

Identify the defining clinical features and vital sign abnormalities.

The patient presents with intestinal angina, mononeuritis multiplex (foot drop), livedo reticularis, fever, weight loss, and new-onset hypertension.

Recognizing this classic constellation of symptoms is essential for formulating a differential diagnosis of systemic vasculitis.

2

Interpret the laboratory findings in the context of the clinical picture.

The patient has elevated inflammatory markers, acute kidney injury without glomerulonephritis (no RBC casts), and a positive Hepatitis B surface antigen.

The absence of an active urinary sediment points away from small-vessel vasculitis, while Hepatitis B positivity strongly suggests polyarteritis nodosa (PAN), a medium-vessel vasculitis.

3

Determine the most appropriate diagnostic test based on the suspected disease mechanism.

Mesenteric and renal angiography is selected over biopsy.

In PAN, medium-sized muscular arteries develop microaneurysms that are clearly visible on angiography. A renal biopsy carries a high risk of life-threatening hemorrhage from these aneurysms and has low yield because it primarily samples the unaffected glomeruli.

Key Concept

Polyarteritis nodosa (PAN) is a medium-vessel necrotizing vasculitis strongly associated with Hepatitis B, frequently causing renal insufficiency without glomerulonephritis and mesenteric ischemia. It is best diagnosed with mesenteric and renal angiography to identify characteristic microaneurysms.

Question 1011Question →

Match each clinical presentation of systemic vasculitis with the most likely specific diagnosis.

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Answer

The presentations match as follows: The older adult with temporal pain and amaurosis fugax has Giant cell arteritis. The patient with hepatitis and mononeuritis multiplex has Polyarteritis nodosa. The patient with saddle-nose deformity and pulmonary-renal syndrome has Granulomatosis with polyangiitis. The young female with unequal arm pressures has Takayasu arteritis.

Each systemic vasculitis has a characteristic clinical phenotype based on the size of the vessels involved and the specific organs targeted. Giant cell arteritis affects large branches of the carotid, causing vision changes and jaw/temporal pain in older adults. Polyarteritis nodosa is a medium-vessel disease associated with Hepatitis B that causes ischemia in mesenteric and peripheral nerve beds. Granulomatosis with polyangiitis is a small-vessel disease producing a triad of upper respiratory, lower respiratory, and renal symptoms. Takayasu arteritis is a large-vessel disease that causes granulomatous thickening of the aortic arch, leading to diminished pulses in young females.

Step-by-Step Solution

1

Analyze the first presentation involving temporal pain, proximal muscle aching (polymyalgia rheumatica), and amaurosis fugax.

These findings are highly specific for large-vessel vasculitis involving branches of the carotid artery, commonly seen in adults over the age of 50.

Identifying the affected vessel size and patient demographic isolates Giant cell arteritis.

2

Evaluate the second vignette featuring a hepatitis infection, abdominal angina, and mononeuritis multiplex.

This points to a medium-vessel vasculitis that spares the pulmonary circulation and is strongly associated with Hepatitis B virus.

Recognizing disease associations and the specific ischemic beds confirms Polyarteritis nodosa.

3

Assess the third scenario with upper respiratory tract involvement, lower respiratory tract involvement, and renal failure.

This classic triad of necrotizing granulomatous inflammation indicates a specific small-vessel vasculitis.

The combination of ear/nose/throat, pulmonary, and renal manifestations is pathognomonic for Granulomatosis with polyangiitis.

4

Examine the final presentation of a young female with upper extremity claudication and asymmetric blood pressures.

This indicates a large-vessel vasculitis primarily affecting the aorta and its main branches, leading to stenosis.

Demographics and clinical signs of aortic arch branch stenosis define Takayasu arteritis.

Key Concept

Clinical presentation and vessel-size classification of systemic vasculitides

Question 1012Question →

A $55$ -year-old man is brought to the emergency department by his wife due to confusion, high fever, and a severe headache that started $12$ hours ago. His medical history is significant for a deceased-donor renal transplant $2$ years ago, for which he takes tacrolimus and mycophenolate mofetil. His temperature is $39.2^\circ\text{C}$ ( $102.6^\circ\text{F}$ ), blood pressure is $105/65\text{ mm Hg}$ , pulse is $115\text{/min}$ , and respirations are $22\text{/min}$ . On physical examination, the patient is lethargic but arousable. He has pronounced nuchal rigidity. Neurologic examination reveals left-sided pronator drift and a sluggish left pupillary reflex. Fundoscopy shows bilateral blurring of the optic discs. Arrange the following management steps in the most appropriate chronological order for this patient.

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Answer

The correct sequence is: Obtain two sets of peripheral blood cultures, followed immediately by administering empiric intravenous antibiotics and dexamethasone. Next, perform a non-contrast CT scan of the head, and finally perform a lumbar puncture to obtain cerebrospinal fluid.

In a patient presenting with classic signs of acute bacterial meningitis (fever, severe headache, nuchal rigidity, altered mental status), the very first step is to draw blood cultures to identify the pathogen. Because this patient is immunocompromised (history of renal transplant) and exhibits focal neurologic deficits (left-sided pronator drift, sluggish pupil) alongside papilledema, there is a high suspicion for elevated intracranial pressure or an intracranial mass lesion. Therefore, a CT scan of the head is mandatory before performing a lumbar puncture to prevent cerebral herniation. Crucially, empiric antibiotics and adjunctive dexamethasone must never be delayed while awaiting neuroimaging; they should be administered immediately after obtaining blood cultures. Once the CT scan rules out mass effect, the lumbar puncture can be safely performed to obtain cerebrospinal fluid for a definitive diagnosis.

Step-by-Step Solution

1

Identify the clinical syndrome and recognize high-risk features.

The patient has signs of acute bacterial meningitis (fever, nuchal rigidity, headache) combined with red flags for elevated intracranial pressure (ICP): immunocompromised state, altered mental status, papilledema, and focal neurologic deficits (pronator drift).

Identifying these red flags dictates that the standard sequence of 'Lumbar Puncture before antibiotics' must be altered to prevent cerebral herniation.

2

Determine the first intervention.

Obtain peripheral blood cultures.

Blood cultures should always be drawn before antimicrobial administration to prevent sterilization of the blood and ensure pathogen identification.

3

Determine the timing of pharmacotherapy.

Administer empiric antibiotics and dexamethasone immediately.

Because neuroimaging is required prior to the lumbar puncture, diagnostic testing will be delayed. Antibiotics must be given immediately after blood cultures are drawn to prevent life-threatening delays in treatment.

4

Determine the correct sequence of diagnostic procedures.

Perform a non-contrast CT scan of the head, followed by a lumbar puncture.

The CT scan is necessary to rule out mass effect or severe elevated ICP. Once cleared, the lumbar puncture can be safely performed to analyze the cerebrospinal fluid.

Key Concept

Management sequence for suspected bacterial meningitis in patients with high-risk features for cerebral herniation.

Estimated Time:2m 0s

Question 1013Question →

A 68-year-old man arrives at the emergency department reporting two days of progressively worsening dyspnea and an inability to lie flat without severe respiratory distress. He has a past medical history of chronic obstructive pulmonary disease (COPD), diet-controlled type 2 diabetes mellitus, and hypertension. Current medications include inhaled tiotropium and oral amlodipine. His temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $174/96\ \text{mm Hg}$ , pulse is $116/\text{min}$ , and respiratory rate is $28/\text{min}$ . Pulse oximetry indicates an oxygen saturation of $87\%$ on room air. Physical examination reveals a patient in moderate respiratory distress using accessory muscles. Jugular venous pressure is elevated to $11\ \text{cm H}_2\text{O}$ above the sternal angle. Pulmonary auscultation reveals a prolonged expiratory phase with diffuse bilateral wheezing and scattered crackles at the lung bases. Cardiac examination shows tachycardia with a regular rhythm and an audible S3 gallop. There is $2+$ pitting edema in the lower extremities bilaterally.

Laboratory results are as follows:
Leukocyte count: $8,200/\text{mm}^3$
Thyroid-stimulating hormone (TSH): $0.2\ \mu\text{IU}/\text{mL}$ (Normal: $0.4\text{-}4.0$ )
Free T4: $1.2\ \text{ng}/\text{dL}$ (Normal: $0.9\text{-}1.7$ )
N-terminal pro-B-type natriuretic peptide (NT-proBNP): $2,800\ \text{pg}/\text{mL}$

Arterial blood gas analysis on room air reveals:
pH: $7.25$
$\text{PaCO}_2$ : $64\ \text{mm Hg}$
$\text{PaO}_2$ : $55\ \text{mm Hg}$
$\text{HCO}_3^-$ : $27\ \text{mEq}/\text{L}$

A portable chest radiograph displays cardiomegaly, bilateral pleural effusions, prominent upper lobe pulmonary vessels, and hyperinflated lung fields. Which of the following is the most appropriate next step in the management of this patient?

Administration of intravenous furosemide and noninvasive positive pressure ventilation

Administration of systemic glucocorticoids and scheduled nebulized ipratropium-albuterol

Infusion of intravenous sodium bicarbonate for an uncompensated metabolic acidosis

Initiation of empiric intravenous vancomycin and piperacillin-tazobactam

Initiation of methimazole to treat high-output cardiac failure

Show answer & explanation

Answer: Administration of intravenous furosemide and noninvasive positive pressure ventilation

Answer

The most appropriate next step is the administration of intravenous furosemide and noninvasive positive pressure ventilation.

The correct answer addresses the patient's underlying acute decompensated heart failure (ADHF). The patient presents with classic signs of left and right heart failure, including an S3 gallop, elevated jugular venous pressure, peripheral edema, and a markedly elevated NT-proBNP. The diffuse wheezing on auscultation represents 'cardiac asthma,' which is caused by peribronchial edema narrowing the airways. The chest radiograph confirms cardiomegaly and pulmonary venous congestion (cephalization, effusions). In patients with ADHF complicated by severe respiratory distress and respiratory acidosis (as seen on the ABG), the immediate management involves noninvasive positive pressure ventilation (NPPV) to reduce the work of breathing and decrease left ventricular preload and afterload, along with intravenous loop diuretics (furosemide) for rapid volume reduction.

Step-by-Step Solution

1

Analyze the clinical presentation to differentiate the cause of respiratory distress.

The patient has a history of COPD and presents with wheezing, but also has an elevated jugular venous pressure, an S3 gallop, peripheral edema, and an elevated NT-proBNP.

These findings are highly specific for volume overload and acute decompensated heart failure, identifying the wheezing as 'cardiac asthma' rather than a primary COPD exacerbation.

2

Interpret the arterial blood gas (ABG) findings.

The ABG shows a low pH (

7.25

) and a highly elevated

\text{PaCO}_2

(

64\ \text{mm Hg}

) with a slightly elevated

\text{HCO}_3^-

(

27\ \text{mEq}/\text{L}

).

This indicates an acute-on-chronic respiratory acidosis resulting from alveolar hypoventilation secondary to severe pulmonary edema, not a primary metabolic derangement.

3

Interpret the thyroid function tests.

The patient has a low TSH but a normal free T4.

This pattern in an acutely ill patient points to euthyroid sick syndrome, ruling out primary hyperthyroidism as a cause for a high-output state.

4

Determine the optimal acute management for acute decompensated heart failure with respiratory acidosis.

Select noninvasive positive pressure ventilation (NPPV) and intravenous loop diuretics (e.g., furosemide).

NPPV rapidly decreases the work of breathing, improves oxygenation, and reduces left ventricular preload and afterload. Furosemide provides necessary diuresis and venodilation to relieve volume overload.

Key Concept

Patients with acute decompensated heart failure can present with prominent wheezing ('cardiac asthma') mimicking a COPD exacerbation; differentiation relies on signs of volume overload (elevated JVP, S3 gallop), biomarkers (BNP), and radiographic evidence of pulmonary venous congestion.

Question 1014Question →

An emergency medical services team brings a 58-year-old male to the emergency department following a new-onset generalized tonic-clonic seizure. His wife reports that he had been complaining of a progressively worsening headache, severe neck stiffness, and subjective fevers for the past 48 hours. His temperature is 39.4°C (102.9°F), blood pressure is 112/68 mmHg, and pulse is 118/min. On physical examination, the patient is obtunded and grimaces upon neck flexion. Funduscopic examination shows no papilledema, but a detailed neurologic exam reveals a new right-sided pronator drift.

Arrange the following interventions in the most appropriate chronological sequence for this patient's management.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for managing suspected bacterial meningitis with high-risk features is to first obtain blood cultures, immediately administer empiric antibiotics and dexamethasone, perform a noncontrast head CT scan, and finally perform a lumbar puncture.

In the management of suspected bacterial meningitis, the first step is always to obtain blood cultures. If the patient has any indications for neuroimaging before a lumbar puncture (e.g., altered mental status, new-onset seizure, focal neurologic deficit, papilledema, or an immunocompromised state), empiric antibiotics and dexamethasone must be administered immediately after the blood cultures are drawn. The CT scan is then performed to ensure there is no mass effect that could lead to herniation during a lumbar puncture. Finally, the lumbar puncture is performed.

Step-by-Step Solution

1

Obtain two sets of blood cultures

Pathogen recovery yield is preserved.

Administering antibiotics before drawing blood cultures drastically reduces the chance of isolating the offending pathogen in the blood.

2

Administer empiric intravenous antibiotics and dexamethasone

Life-saving treatment is initiated.

Meningitis is a medical emergency; delaying antimicrobial therapy while waiting for a CT scan or lumbar puncture significantly increases mortality and neurological morbidity.

3

Perform a noncontrast head CT scan

Intracranial mass effect or midline shift is ruled out.

This patient has altered mental status, a recent seizure, and a focal neurologic deficit. These are all strict indications for a head CT before a lumbar puncture to prevent fatal brain herniation.

4

Perform a lumbar puncture

Cerebrospinal fluid (CSF) is obtained for analysis and culture.

Once the CT scan confirms it is safe, CSF analysis is required to tailor ongoing antimicrobial therapy, even though empiric antibiotics have already been given.

Key Concept

Management sequencing for suspected bacterial meningitis in patients with indications for cranial imaging before lumbar puncture.

Estimated Time:1m 30s

Question 1015Question →

A 62-year-old man is evaluated on postoperative day 3 following an uncomplicated laparoscopic inguinal hernia repair. He reports the acute onset of severe pain, swelling, and redness in his right first metatarsophalangeal joint that began overnight. The patient has a history of hypertension and hyperlipidemia. His temperature is 37.8°C (100.0°F), blood pressure is 135/85 mmHg, and pulse is 88/min. Physical examination reveals an exquisitely tender, warm, and erythematous right big toe. Synovial fluid analysis of the affected joint reveals a leukocyte count of 22,000/mm³ and the presence of needle-shaped, negatively birefringent crystals. Gram stain shows no organisms. Which of the following is the most appropriate next step in management?

Prescribe oral indomethacin

Administer intravenous vancomycin and ceftriaxone

Initiate therapy with oral allopurinol

Perform surgical irrigation and debridement of the joint

Administer intravenous furosemide

Show answer & explanation

Answer: Prescribe oral indomethacin

Answer

The most appropriate next step in management is to prescribe an oral nonsteroidal anti-inflammatory drug, such as indomethacin.

This patient is experiencing an acute gout flare, which is strongly suggested by his presentation of podagra (inflammation of the first metatarsophalangeal joint) and confirmed by the synovial fluid demonstrating needle-shaped, negatively birefringent monosodium urate crystals. Acute gout attacks frequently occur in hospitalized or postoperative patients due to physiological stress, dehydration, or changes in diet and medications. The most appropriate immediate management is to reduce joint inflammation. First-line therapies for an acute gout attack include oral nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin, colchicine, or systemic/intra-articular glucocorticoids. Since the patient has no apparent contraindications (such as active peptic ulcer disease or severe kidney injury), an NSAID is the correct next step.

Step-by-Step Solution

1

Evaluate the clinical presentation and physical exam findings.

The patient presents with acute monoarthritis of the first metatarsophalangeal joint (podagra), highly characteristic of a gout flare.

Identifying the specific pattern of joint involvement helps narrow the differential diagnosis between crystalline arthropathy, infectious arthritis, and autoimmune etiologies.

2

Interpret the synovial fluid analysis.

The fluid shows a moderately elevated leukocyte count (22,000/mm³) and needle-shaped, negatively birefringent crystals.

These microscopic findings confirm the diagnosis of acute monosodium urate crystal deposition (gout) and effectively rule out septic arthritis given the negative Gram stain.

3

Determine the optimal acute management.

Select a medication to rapidly halt the inflammatory cascade.

First-line agents for an acute gout flare include NSAIDs (e.g., indomethacin), colchicine, or systemic/intra-articular corticosteroids.

Key Concept

Diagnosis and acute management of gouty arthritis

Question 1016Question →

A $72$ -year-old man is evaluated on postoperative day $1$ following an elective total hip arthroplasty due to severe osteoarthritis. Prior to surgery, his hemoglobin was $11.2 \text{ g/dL}$ . Postoperatively, his hemoglobin dropped to $6.8 \text{ g/dL}$ , and a transfusion of $2$ units of packed red blood cells was ordered. One hour into the transfusion of the second unit, he reports severe shortness of breath and a new-onset dry cough. His medical history is significant for hypertension, type $2$ diabetes mellitus, and coronary artery disease.

Vital signs are:
- Temperature: $37.8^\circ\text{C}$ ( $100.0^\circ\text{F}$ )
- Blood pressure: $175/95 \text{ mmHg}$
- Heart rate: $112/\text{min}$
- Respiratory rate: $28/\text{min}$
- SpO $_2$ : $88\%$ on room air

Physical examination reveals elevated jugular venous pressure to $9 \text{ cm H}_2\text{O}$ . Cardiac auscultation reveals a regular tachycardia with a new $S_3$ gallop. Pulmonary examination reveals bibasilar crackles extending midway up the lung fields. There is no rash or stridor.

Laboratory studies obtained one hour prior to the transfusion:

Test	Result
Hemoglobin	$6.8 \text{ g/dL}$
Hematocrit	$21\%$
Leukocyte count	$8,400/\text{mm}^3$
Platelet count	$210,000/\text{mm}^3$
Sodium	$138 \text{ mEq/L}$
Potassium	$4.2 \text{ mEq/L}$
Blood urea nitrogen	$22 \text{ mg/dL}$
Creatinine	$1.2 \text{ mg/dL}$

Arterial blood gas (room air, during acute event):
- pH: $7.48$
- pCO $_2$ : $30 \text{ mmHg}$
- pO $_2$ : $55 \text{ mmHg}$

Which of the following is the most appropriate next step in management?

Discontinue the transfusion and administer intravenous epinephrine

Pause the transfusion, administer intravenous acetaminophen and diphenhydramine, and resume at a slower rate

Discontinue the transfusion, obtain blood cultures, and administer broad-spectrum intravenous antibiotics

Discontinue the transfusion and administer intravenous furosemide

Discontinue the transfusion and administer inhaled albuterol

Show answer & explanation

Answer: Discontinue the transfusion and administer intravenous furosemide

Answer

The correct answer is to discontinue the transfusion and administer intravenous furosemide.

This patient's acute respiratory distress, hypertension, elevated jugular venous pressure,

S_3

gallop, and bibasilar crackles during a blood transfusion are classic for Transfusion-Associated Circulatory Overload (TACO). TACO is a form of cardiogenic pulmonary edema caused by the rapid infusion of blood products, particularly in older patients or those with underlying cardiac dysfunction. The immediate and most appropriate management is to stop the transfusion, provide respiratory support (supplemental oxygen), and administer an intravenous loop diuretic such as furosemide to rapidly reduce intravascular volume and alleviate the pulmonary edema.

Step-by-Step Solution

1

Analyze the patient's acute symptoms and vital signs during the blood transfusion.

The patient developed acute respiratory distress, severe hypoxia, significant hypertension, tachycardia, jugular venous distension (JVD), and an

S_3

gallop.

To identify the dominant pathophysiological process causing the acute deterioration.

2

Differentiate between the life-threatening transfusion reactions.

The presence of hypertension, JVD, and an

S_3

gallop in a patient with a history of coronary artery disease strongly indicates fluid overload leading to cardiogenic pulmonary edema (Transfusion-Associated Circulatory Overload, or TACO). It is distinguished from Transfusion-Related Acute Lung Injury (TRALI) and anaphylaxis, which typically present with hypotension.

Different acute transfusion reactions require distinctly different immediate management strategies.

3

Determine the most appropriate immediate management for TACO.

The first step is to immediately stop the transfusion to prevent further volume loading, followed by medical diuresis (e.g., intravenous furosemide) and respiratory support.

To rapidly decrease intravascular volume and alleviate the cardiopulmonary strain.

Key Concept

Transfusion-associated circulatory overload (TACO) presents with signs of volume overload (hypertension, JVD,

S_3

gallop, pulmonary edema) and is managed by immediately stopping the transfusion and administering intravenous diuretics.

Question 1017Question →

A 58-year-old man presents to the outpatient clinic with a 2-day history of steady left lower quadrant abdominal pain. The pain is associated with mild nausea and a decreased appetite. He denies vomiting, hematochezia, or melena. He has a history of essential hypertension treated with amlodipine. He underwent a screening colonoscopy three years ago, which revealed scattered diverticula but no polyps or malignancy. Vital signs are temperature 37.6°C (99.7°F), blood pressure 132/82 mmHg, heart rate 84/min, and respiratory rate 16/min. The abdomen is soft and non-distended. There is focal tenderness to deep palpation in the left lower quadrant, but no guarding or rebound tenderness is appreciated. Complete blood count shows a leukocyte count of 11,200/mm³. A CT scan of the abdomen and pelvis with contrast reveals focal thickening of the sigmoid colon wall and adjacent pericolic fat stranding. There are no fluid collections, abscesses, pneumatosis, or free intraperitoneal air. Which of the following is the most appropriate next step in management?

Hospitalization and initiation of intravenous piperacillin-tazobactam

Urgent colonoscopy to evaluate for underlying malignancy

Oral fluid hydration, symptom control, and observation

Initiation of oral ciprofloxacin and metronidazole

CT-guided percutaneous drainage of the affected colonic segment

Show answer & explanation

Answer: Oral fluid hydration, symptom control, and observation

Answer

Oral fluid hydration, symptom control, and observation

The correct approach is oral fluid hydration, symptom control, and observation. This patient has acute uncomplicated diverticulitis, defined as localized colonic inflammation without evidence of complications (such as an abscess, fistula, or free perforation) on CT imaging, and no signs of systemic toxicity or immunosuppression. Current guidelines from the American Gastroenterological Association (AGA) strongly advise against the routine use of antibiotics for acute uncomplicated diverticulitis in immunocompetent patients. Large randomized trials have demonstrated that antibiotic therapy in this specific population offers no benefit in time to clinical recovery or the prevention of complications (such as progression to perforation or abscess). Appropriate management consists of temporary bowel rest (a clear liquid diet), adequate oral hydration, and close outpatient follow-up.

Step-by-Step Solution

1

Analyze the clinical presentation and diagnostic imaging.

The patient has left lower quadrant pain, mild leukocytosis, and a CT scan showing sigmoid thickening and fat stranding without abscess or perforation. This confirms a diagnosis of acute uncomplicated diverticulitis.

To classify the disease severity, which dictates the need for medical versus interventional management.

2

Assess the patient's systemic stability and risk factors.

The patient is immunocompetent, hemodynamically stable, and does not meet criteria for Systemic Inflammatory Response Syndrome (SIRS).

To determine if inpatient admission or aggressive systemic therapy is warranted.

3

Select the guideline-directed management for this specific disease state.

Current guidelines indicate that immunocompetent patients with acute uncomplicated diverticulitis should be managed conservatively with oral hydration and bowel rest without routine antibiotics.

Recent high-quality evidence shows antibiotics do not accelerate recovery or prevent complications in mild cases, emphasizing antibiotic stewardship.

Key Concept

Management of acute uncomplicated diverticulitis

Estimated Time:1m 30s

Question 1018Question →

A 26-year-old woman with a 3-year history of systemic lupus erythematosus (SLE) presents to the clinic with 2 weeks of worsening bilateral lower extremity edema and newly frothy urine. Her current medications include hydroxychloroquine and low-dose prednisone. Vital signs show a blood pressure of 152/94 mm Hg. Physical examination reveals 2+ pitting edema up to the mid-calves. You suspect new-onset lupus nephritis. Arrange the following steps in the standard sequential order for the diagnostic evaluation and subsequent therapeutic management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: Noninvasive laboratory evaluation, followed by Percutaneous renal biopsy, then Induction immunosuppressive therapy, and finally Transition to maintenance immunosuppressive therapy.

The standard of care for new-onset lupus nephritis begins with noninvasive confirmation of proteinuria and serologic activity. Once confirmed, a renal biopsy is strictly required to classify the disease (e.g., distinguishing between proliferative and pure membranous nephritis), as this classification dictates treatment. For proliferative classes, treatment is divided into a short, aggressive induction phase to halt renal inflammation, followed by a prolonged, less toxic maintenance phase to prevent relapse.

Step-by-Step Solution

1

Identify the clinical presentation of a severe lupus flare with renal involvement.

The patient has new-onset edema, hypertension, and frothy urine, highly suggestive of lupus nephritis.

Recognizing the clinical signs of renal involvement dictates the need for an immediate targeted diagnostic workup.

2

Determine the first step in the diagnostic workup.

Order noninvasive tests, including a spot urine protein-to-creatinine ratio, anti-dsDNA, and C3/C4 levels.

Noninvasive testing quantifies the degree of renal impairment and confirms immunologic activity before subjecting the patient to an invasive procedure.

3

Identify the mandatory step prior to initiating targeted pharmacotherapy.

Perform a percutaneous renal biopsy.

Lupus nephritis has distinct histopathologic classes (I through VI) that require completely different management strategies. Tissue diagnosis is mandatory to guide therapy.

4

Sequence the phases of pharmacological treatment for severe lupus nephritis.

Begin with intense induction therapy, followed months later by maintenance therapy.

Aggressive initial immunosuppression (induction) is necessary to halt acute damage, while a stepped-down regimen (maintenance) minimizes long-term drug toxicity while preventing relapse.

Key Concept

Stepwise diagnostic and therapeutic management of Lupus Nephritis

Question 1019Question →

A 74-year-old woman is evaluated in the emergency department for a 3-day history of progressively worsening shortness of breath and increased sputum production. She has a medical history of chronic obstructive pulmonary disease (COPD), heart failure with preserved ejection fraction, and type 2 diabetes mellitus. Her current medications include lisinopril, amlodipine, metformin, and a daily tiotropium inhaler. She has a 40-pack-year smoking history. Her temperature is 37.3 °C (99.1 °F), blood pressure is 138/86 mm Hg, pulse is 92/min, and respirations are 24/min. Pulse oximetry shows an oxygen saturation of 89% on room air. The patient is sitting upright and using accessory muscles of respiration. The jugular venous pressure is 6 cm H2O. Chest auscultation reveals a prolonged expiratory phase with diffuse expiratory wheezing bilaterally. Cardiac examination shows a regular rate and rhythm with a normal S1 and S2; there are no murmurs or gallops. There is no peripheral edema. Laboratory studies show:

Leukocyte count: 9,500/mm³
Serum $Na^+$ : 139 mEq/L
Serum $K^+$ : 4.1 mEq/L
Serum $Cl^-$ : 96 mEq/L
Serum $HCO_3^-$ : 33 mEq/L
BUN: 18 mg/dL
Creatinine: 0.9 mg/dL
Thyroid-stimulating hormone (TSH): 0.15 µU/mL (Normal: 0.4–4.0 µU/mL)
Free thyroxine (T4): 1.1 ng/dL (Normal: 0.9–2.4 ng/dL)

An arterial blood gas on room air shows:
pH: 7.35
$PaCO_2$ : 60 mm Hg
$PaO_2$ : 58 mm Hg

A chest radiograph shows hyperinflated lungs and flattened diaphragms, with no focal consolidation, pleural effusion, or pulmonary vascular congestion. Which of the following is the most appropriate next step in management of this patient's current condition?

Administer nebulized albuterol-ipratropium and systemic glucocorticoids

Administer intravenous furosemide and restrict oral fluid intake

Administer intravenous piperacillin-tazobactam and vancomycin

Administer a continuous intravenous infusion of sodium bicarbonate

Initiate therapy with oral methimazole

Show answer & explanation

Answer: Administer nebulized albuterol-ipratropium and systemic glucocorticoids

Answer

The most appropriate next step is to administer nebulized albuterol-ipratropium and systemic glucocorticoids.

The patient presents with cardinal symptoms of an acute exacerbation of chronic obstructive pulmonary disease (AECOPD), including worsened dyspnea, increased sputum production, and wheezing. The physical examination showing accessory muscle use and a prolonged expiratory phase, along with a chest radiograph demonstrating hyperinflation without infiltrates or pulmonary congestion, strongly supports this diagnosis. The most appropriate initial management for AECOPD includes short-acting bronchodilators (such as albuterol and ipratropium), systemic glucocorticoids (e.g., prednisone), and supplemental oxygen to maintain saturations between 88% and 92%. The arterial blood gas confirms a baseline chronic CO2 retention that is well compensated (pH 7.35, elevated

PaCO_2

, and elevated

HCO_3^-

), which is typical for a patient with severe, chronic COPD.

Step-by-Step Solution

1

Analyze the clinical presentation and physical examination findings.

The patient presents with worsened dyspnea, increased sputum, accessory muscle use, and diffuse wheezing, with a normal JVP and no peripheral edema.

To distinguish between a primary pulmonary etiology (like a COPD exacerbation) and a primary cardiac etiology (like acute decompensated heart failure).

2

Interpret the laboratory data, arterial blood gas, and imaging.

Chest X-ray shows hyperinflation without congestion. ABG shows a fully compensated respiratory acidosis (pH 7.35, high

PaCO_2

, high

HCO_3^-

). Thyroid panel reveals euthyroid sick syndrome.

To confirm the diagnosis of COPD exacerbation and rule out co-occurring acid-base, infectious, or endocrine derangements.

3

Select the appropriate evidence-based intervention.

The standard of care for an acute COPD exacerbation is selected: short-acting bronchodilators, systemic glucocorticoids, and targeted oxygen therapy.

To alleviate bronchospasm, reduce airway inflammation, and improve oxygenation safely.

Key Concept

Diagnosis and initial management of acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Question 1020Question →

A 48-year-old man is brought to the emergency department by his wife due to a 2-week history of worsening shortness of breath, fever, and coughing up blood-tinged sputum. He has a past medical history of chronic rhinosinusitis refractory to antibiotics, recurrent epistaxis, and bilateral knee pain over the past year. His only medication is ibuprofen as needed.

His temperature is $38.3^\circ\text{C}$ ( $100.9^\circ\text{F}$ ), blood pressure is $155/95\text{ mm Hg}$ , pulse is $112/\text{min}$ , and respirations are $26/\text{min}$ . Oxygen saturation is $89\%$ on room air.

Physical examination shows ulceration of the nasal septum and a saddle nose deformity. Lung auscultation reveals bilateral fine crackles. Heart sounds are normal. There is no peripheral edema.

Laboratory results are as follows:

Test	Result	Reference Range
Leukocyte count	$14,500/\text{mm}^3$	$4,500-11,000/\text{mm}^3$
Hemoglobin	$9.8\text{ g/dL}$	$13.5-17.5\text{ g/dL}$
Platelet count	$450,000/\text{mm}^3$	$150,000-400,000/\text{mm}^3$
Blood urea nitrogen	$52\text{ mg/dL}$	$8-20\text{ mg/dL}$
Serum creatinine	$3.1\text{ mg/dL}$	$0.7-1.3\text{ mg/dL}$
Thyroid-stimulating hormone (TSH)	$0.2\ \mu\text{U/mL}$	$0.4-4.0\ \mu\text{U/mL}$
Free T4	$0.8\text{ ng/dL}$	$0.9-2.0\text{ ng/dL}$

Urinalysis shows 3+ protein and large blood; microscopy reveals 25-50 RBCs/hpf and occasional red blood cell casts.

An arterial blood gas on room air shows:
pH: $7.28$
PaO $_2$ : $58\text{ mm Hg}$
PaCO $_2$ : $25\text{ mm Hg}$
HCO $_3^-$ : $11\text{ mEq/L}$

A chest X-ray shows multiple bilateral nodular opacities, several of which are cavitating.

Which of the following is the most appropriate next step in the management of this patient?

Administer intravenous methylprednisolone and obtain proteinase 3 antineutrophil cytoplasmic antibody levels

Administer intravenous sodium bicarbonate and prepare for endotracheal intubation

Administer intravenous furosemide and initiate noninvasive positive pressure ventilation

Start empiric intravenous vancomycin and piperacillin-tazobactam

Initiate intravenous levothyroxine and obtain a thyroid ultrasound

Show answer & explanation

Answer: Administer intravenous methylprednisolone and obtain proteinase 3 antineutrophil cytoplasmic antibody levels

Answer

The most appropriate next step is to administer intravenous methylprednisolone and obtain proteinase 3 antineutrophil cytoplasmic antibody levels.

The correct answer addresses the urgent need to suppress the severe autoimmune inflammation characteristic of Granulomatosis with polyangiitis (GPA). This patient presents with the classic triad of upper respiratory tract involvement (saddle nose deformity, nasal ulceration), lower respiratory tract involvement (cavitary lung nodules, hemoptysis), and focal necrotizing glomerulonephritis (acute kidney injury with RBC casts). This presentation represents a rapidly fatal pulmonary-renal syndrome. The most appropriate initial step is the immediate administration of high-dose systemic corticosteroids (such as intravenous methylprednisolone) to halt immune-mediated tissue destruction, concurrently with diagnostic serologic testing for c-ANCA (specifically proteinase 3 [PR3] antibodies).

Step-by-Step Solution

1

Analyze the clinical presentation.

The patient exhibits the classic triad of Granulomatosis with polyangiitis (GPA): upper respiratory tract involvement (nasal septal ulceration, saddle nose), lower respiratory tract involvement (cavitary lung nodules, hemoptysis), and focal necrotizing glomerulonephritis (acute kidney injury with RBC casts).

Recognizing this triad is crucial to diagnose GPA, a life-threatening pulmonary-renal syndrome.

2

Interpret the arterial blood gas using Winter's formula.

Expected PaCO2 = (1.5 × 11) + 8 = 24.5 ± 2. The measured PaCO2 of 25 mm Hg indicates perfect respiratory compensation for the metabolic acidosis.

To rule out a superimposed, uncompensated respiratory acidosis that would urgently require mechanical ventilation.

3

Evaluate the thyroid function tests.

Low TSH and low Free T4 in the setting of severe systemic illness indicates euthyroid sick syndrome (nonthyroidal illness syndrome).

To rule out true hypothyroidism and avoid unnecessary and potentially harmful thyroid hormone replacement.

4

Determine the optimal immediate management.

Initiate high-dose systemic corticosteroids (e.g., intravenous methylprednisolone) and order serologic testing for c-ANCA (PR3 antibodies).

Delaying immunosuppressive therapy in organ-threatening ANCA-associated vasculitis can lead to irreversible renal failure or fatal pulmonary hemorrhage.

Key Concept

Diagnosis and acute management of Granulomatosis with polyangiitis (GPA) presenting as a pulmonary-renal syndrome.

Internal Medicine

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