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Question 1081Question →

Correlate each pediatric clinical presentation with the most appropriate primary therapeutic intervention or management strategy.

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Items

A 21-day-old infant is evaluated for extreme lethargy and poor feeding. Physical examination reveals a bulging anterior fontanelle. Cerebrospinal fluid analysis demonstrates significant pleocytosis and the presence of Gram-positive rods.
A 5-year-old patient has experienced 6 days of unremitting fever. Clinical findings include bilateral nonexudative bulbar conjunctivitis, fissured erythematous lips, and noticeable erythema of the palmar and plantar surfaces.
A 10-year-old patient residing in a heavily wooded region develops acute unilateral facial nerve palsy. The medical history is significant for an expanding erythematous annular lesion with central clearing noted two weeks prior.
A 16-year-old adolescent presents with profound fatigue, generalized lymphadenopathy, and a new-onset, diffuse morbilliform eruption that appeared three days after initiating amoxicillin therapy for suspected streptococcal pharyngitis.

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Answer

The neonate with Gram-positive rods requires ampicillin and an aminoglycoside. The child with prolonged fever and mucocutaneous changes requires intravenous immunoglobulin and high-dose acetylsalicylic acid. The child with an annular rash and facial palsy requires oral doxycycline. The adolescent with an amoxicillin-induced rash requires discontinuation of antibacterial therapy and supportive care.
Each clinical scenario uniquely describes a classic pediatric infectious or inflammatory disease requiring a highly specific initial intervention. Listeria meningitis mandates ampicillin due to intrinsic cephalosporin resistance. Kawasaki disease is an inflammatory vasculitis requiring IVIG and aspirin. Early disseminated Lyme disease with isolated facial palsy is treated with doxycycline. EBV-associated amoxicillin rash is a non-allergic viral phenomenon requiring cessation of the unnecessary antibiotic.

Step-by-Step Solution

1
Analyze the 21-day-old infant's presentation.
Identify Listeria monocytogenes meningitis based on age and Gram-positive rods in the CSF.
Listeria is a common neonatal pathogen that is uniquely resistant to third-generation cephalosporins, necessitating ampicillin in combination with an aminoglycoside for synergistic bactericidal activity.
2
Analyze the 5-year-old patient's presentation.
Diagnose Kawasaki disease based on fever for ≥5 days plus characteristic mucocutaneous findings.
Kawasaki disease is a medium-vessel vasculitis. Immediate treatment with intravenous immunoglobulin (IVIG) and high-dose aspirin is required to reduce systemic inflammation and the risk of coronary artery aneurysms.
3
Analyze the 10-year-old patient's presentation.
Identify early disseminated Lyme disease presenting with isolated cranial nerve VII palsy.
The history of erythema migrans followed by facial palsy points to Borrelia burgdorferi infection. Oral doxycycline is preferred as it effectively treats the underlying infection and achieves adequate CNS penetration.
4
Analyze the 16-year-old adolescent's presentation.
Recognize an amoxicillin-induced rash in the setting of infectious mononucleosis (Epstein-Barr virus).
When patients with EBV are erroneously prescribed aminopenicillins for presumed strep throat, a distinct, widespread immune-mediated rash often develops. Since the underlying cause is viral, stopping the antibiotic and providing supportive care is the correct action.

Key Concept

Empiric antimicrobial selection and management of distinct pediatric infectious and inflammatory syndromes.
Question 1082Question →

Match the following diuretic medications with their primary site and mechanism of action within the nephron.

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Items

Acetazolamide
Furosemide
Hydrochlorothiazide
Spironolactone

Matches

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Answer

Acetazolamide matches with the proximal convoluted tubule; Furosemide matches with the thick ascending limb; Hydrochlorothiazide matches with the early distal convoluted tubule; Spironolactone matches with the cortical collecting duct.
Each class of diuretics has a specific molecular target along the nephron, which determines its clinical indications, efficacy, and side effect profile.

Step-by-Step Solution

1
Identify the target for Acetazolamide
Proximal convoluted tubule
Acetazolamide inhibits carbonic anhydrase, which is predominantly located in the proximal convoluted tubule.
2
Identify the target for Furosemide
Thick ascending limb
Loop diuretics like furosemide block the Na+-K+-2Cl- cotransporter in the thick ascending limb of the loop of Henle.
3
Identify the target for Hydrochlorothiazide
Early distal convoluted tubule
Thiazide diuretics block the Na+-Cl- cotransporter located in the early segment of the distal convoluted tubule.
4
Identify the target for Spironolactone
Cortical collecting duct
Spironolactone acts as an aldosterone receptor antagonist in the principal cells of the cortical collecting duct.

Key Concept

Mechanisms and sites of action of diuretic classes
Estimated Time:45s
Question 1083Question →

For each distinct laboratory and clinical profile in patients presenting with bleeding symptoms, match the most accurate underlying diagnosis.

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Items

Prolonged activated partial thromboplastin time (aPTT) that corrects with a mixing study, normal prothrombin time (PT), and normal platelet count in a male with recurrent hemarthrosis.
Prolonged PT, prolonged aPTT, decreased fibrinogen, elevated D-dimer, and thrombocytopenia in a patient with gram-negative bacteremia.
Isolated prolonged PT, normal aPTT, and normal platelet count in a patient with a history of recurrent mild epistaxis.
Prolonged bleeding time, prolonged aPTT, normal PT, and normal platelet count in a female with heavy menstrual bleeding.

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Answer

The correct matches logically connect specific patterns of intrinsic, extrinsic, and common pathway coagulation defects with their classic hematologic disorders.
Each coagulation profile maps directly to a specific physiological part of the hemostatic pathway. Isolated correctable aPTT prolongation implies an intrinsic factor deficiency. Global cascade prolongation with thrombocytopenia indicates consumptive coagulopathy. Isolated PT prolongation zeroes in on the extrinsic pathway. Combined aPTT and bleeding time prolongation indicates concurrent primary and secondary hemostatic defects.

Step-by-Step Solution

1
Analyze the first profile showing isolated aPTT prolongation that corrects with a mixing study.
Points to an intrinsic pathway factor deficiency (Hemophilia).
A mixing study correction rules out autoantibodies (inhibitors), identifying a pure factor deficiency in the intrinsic cascade (Factor VIII, IX, XI, or XII).
2
Evaluate the second profile demonstrating global coagulation failure with thrombocytopenia.
Corresponds to a consumptive coagulopathy (DIC).
Sepsis triggers widespread tissue factor release, simultaneously consuming clotting factors and platelets while activating fibrinolysis.
3
Examine the third profile characterized by an isolated PT prolongation.
Indicates an isolated extrinsic pathway defect.
Factor VII is uniquely responsible for the extrinsic pathway; an isolated deficiency will only prolong the PT without affecting the aPTT or bleeding time.
4
Assess the fourth profile featuring combined primary (bleeding time) and secondary (aPTT) hemostasis defects.
Identifies von Willebrand disease.
vWF mediates initial platelet adhesion (primary hemostasis) and stabilizes Factor VIII in the plasma (secondary hemostasis), leading to this dual laboratory abnormality.

Key Concept

Interpretation of coagulation panels and platelet counts to diagnose inherited and acquired bleeding disorders.
Estimated Time:1m 30s
Question 1084Question →

Match each clinical scenario involving the use of a rheumatologic medication to its most critical associated toxicity, pharmacological interaction, or pre-treatment screening requirement.

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Items

A patient with established rheumatoid arthritis begins treatment with a pyrimidine synthesis inhibitor. Months later, she decides to pursue pregnancy, necessitating an accelerated drug elimination protocol.
An individual diagnosed with granulomatosis with polyangiitis is scheduled to receive a chimeric monoclonal antibody targeting CD20 to induce disease remission.
A patient with a history of recurrent gouty arthritis managed with daily allopurinol is evaluated for the addition of a purine analog immunosuppressant.
A recently diagnosed patient with systemic lupus erythematosus starts a cornerstone antimalarial therapy known to reduce disease flares and improve long-term survival.
A patient with severe rheumatoid arthritis is treated with a biologic therapy targeting tumor necrosis factor alpha. Several months later, the patient develops a chronic cough, night sweats, and apical lung cavitations.

Matches

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Answer

The correct matching pairs are: Leflunomide with teratogenicity requiring cholestyramine washout; Rituximab with hepatitis B reactivation risk; Azathioprine with life-threatening pancytopenia risk when combined with allopurinol; Hydroxychloroquine with irreversible retinal toxicity risk; and TNF-alpha inhibitors with latent tuberculosis reactivation risk.
Each rheumatologic medication possesses a highly specific toxicity profile and mechanism of action that dictates its clinical management. Leflunomide requires a cholestyramine washout for pregnancy due to its long half-life. Rituximab profoundly depletes B cells, risking severe viral reactivation like HBV. Azathioprine metabolism is directly blocked by allopurinol, leading to severe pancytopenia. Hydroxychloroquine causes dose-dependent retinal toxicity requiring specialized OCT screening. Lastly, TNF-alpha inhibitors disrupt maintaining granulomas, necessitating screening for latent tuberculosis.

Step-by-Step Solution

1
Identify the pyrimidine synthesis inhibitor (leflunomide) and its specific pharmacokinetic property.
Leflunomide undergoes enterohepatic circulation causing a long half-life and is teratogenic, matching the need for cholestyramine washout.
Cholestyramine interrupts enterohepatic circulation, allowing safe drug elimination before pregnancy.
2
Identify the anti-CD20 monoclonal antibody (rituximab) and its infectious risks.
Rituximab causes profound B-cell depletion, matching the risk for hepatitis B reactivation and progressive multifocal leukoencephalopathy.
B cells are necessary for controlling certain latent viral infections.
3
Identify the purine analog (azathioprine) and its interaction with the patient's existing gout medication (allopurinol).
Allopurinol blocks xanthine oxidase, matching the risk of toxic azathioprine metabolite accumulation and fatal pancytopenia.
Xanthine oxidase is required to safely degrade 6-mercaptopurine (the active metabolite of azathioprine).
4
Identify the antimalarial agent (hydroxychloroquine) and its long-term monitoring requirements.
Hydroxychloroquine accumulates in melanin-rich tissues, matching the risk of bull's-eye maculopathy and the need for regular OCT screening.
Early detection of retinal toxicity prevents irreversible vision loss.
5
Identify the biologic agent causing apical lung cavitations (TNF-alpha inhibitor) and its pre-treatment requirement.
TNF-alpha inhibitors disrupt granulomas, matching the risk of tuberculosis reactivation and the need for IGRA screening.
TNF-alpha is essential for maintaining the granulomas that keep mycobacterial infections in a latent state.

Key Concept

Adverse effects, drug interactions, and pre-treatment screening requirements for disease-modifying antirheumatic drugs (DMARDs) and biologic agents.
Question 1085Question →

An internal medicine clinical pathways committee is updating hospital protocols for the acute management of oncologic complications. Match each of the following patient presentations—characterized by specific clinical signs, symptoms, and targeted laboratory data—to the single most appropriate initial therapeutic intervention according to current clinical guidelines.

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Items

A 69-year-old man with metastatic prostate cancer who presents with rapidly progressive bilateral lower extremity weakness, a distinct sensory deficit below the umbilicus, and new-onset urinary retention.
A 41-year-old woman undergoing induction chemotherapy for acute myeloid leukemia who develops oliguria, an electrocardiogram demonstrating peaked T waves, and laboratory studies revealing severe hyperuricemia and low serum calcium.
A 61-year-old woman with advanced breast cancer who presents with profound lethargy, severe constipation, an abbreviated QT interval on electrocardiography, and a serum calcium level of 14.6 mg/dL14.6\text{ mg/dL}.
A 54-year-old man receiving systemic chemotherapy who presents with a temperature of 39.4∘C39.4^\circ\text{C} (102.9∘F102.9^\circ\text{F}), no focal infectious symptoms on examination, and an absolute neutrophil count of 300/μL300/\mu\text{L}.

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Answer

The correct matches pair each oncologic emergency with its definitive initial management: malignant spinal cord compression requires immediate glucocorticoids; tumor lysis syndrome requires fluids and rasburicase; severe hypercalcemia requires aggressive saline followed by bisphosphonates; and febrile neutropenia requires immediate empiric antipseudomonal antibiotics.
The correct matches represent the consensus guidelines for acute oncologic emergencies. Suspected malignant spinal cord compression necessitates immediate corticosteroids to mitigate permanent neurologic damage. Tumor lysis syndrome requires vigorous hydration and rasburicase to address hyperuricemia and preserve renal function. Severe hypercalcemia requires initial aggressive isotonic saline to correct profound volume depletion before bisphosphonates take effect. Febrile neutropenia demands immediate blood cultures and the empiric initiation of an antipseudomonal beta-lactam to prevent fulminant sepsis.

Step-by-Step Solution

1
Analyze the first clinical presentation featuring progressive lower extremity weakness, a sensory level, and urinary retention in a patient with prostate cancer.
Identify the condition as malignant spinal cord compression (MSCC).
These findings represent a neurologic emergency requiring immediate intervention to prevent irreversible paralysis.
2
Determine the initial pharmacological step for malignant spinal cord compression.
Match with 'Immediate administration of high-dose intravenous glucocorticoids'.
Corticosteroids rapidly decrease spinal cord edema, relieving pressure while awaiting definitive imaging (MRI) and surgical or radiotherapeutic management.
3
Analyze the second presentation involving oliguria, peaked T waves, hyperuricemia, and hypocalcemia following chemotherapy.
Identify the condition as tumor lysis syndrome (TLS).
Massive tumor cell death releases intracellular contents (potassium, phosphate, and nucleic acids which convert to uric acid) into the bloodstream, precipitating acute kidney injury.
4
Determine the appropriate management for established tumor lysis syndrome.
Match with 'Continuous telemetry, aggressive isotonic fluid resuscitation, and administration of rasburicase'.
Aggressive fluid hydration maintains urine output, telemetry monitors hyperkalemia-induced arrhythmias, and rasburicase enzymatically degrades uric acid to prevent renal tubule crystallization.
5
Analyze the third presentation marked by lethargy, constipation, short QT interval, and calcium > 14 mg/dL.
Identify severe hypercalcemia of malignancy.
Symptoms of severe hypercalcemia typically emerge at levels above 14 mg/dL and induce profound intravascular volume depletion via nephrogenic diabetes insipidus.
6
Select the initial management for severe hypercalcemia of malignancy.
Match with 'Rapid volume expansion with intravenous 0.9% saline and subsequent administration of zoledronic acid'.
Restoration of intravascular volume with normal saline is always the first step, subsequently paired with bisphosphonates to inhibit osteoclastic bone resorption.
7
Analyze the fourth presentation showing fever in the setting of severe chemotherapy-induced neutropenia without a focal source.
Identify febrile neutropenia.
An absolute neutrophil count < 500/μL combined with fever is a life-threatening immunologic emergency where typical signs of focal infection are often absent.
8
Identify the mandatory initial intervention for febrile neutropenia.
Match with 'Immediate procurement of blood cultures followed by prompt initiation of an antipseudomonal beta-lactam'.
Empiric antibiotics must be started within 60 minutes of presentation due to the high risk of rapid clinical deterioration from uncontained bacterial proliferation, particularly from Pseudomonas aeruginosa.

Key Concept

Recognition and appropriate initial pharmacological management of acute oncologic emergencies (Malignant Spinal Cord Compression, Tumor Lysis Syndrome, Severe Hypercalcemia, and Febrile Neutropenia).
Estimated Time:2m 0s
Question 1086Question →

Match the following laboratory profiles of calcium, phosphorus, and parathyroid hormone (PTH) to the most likely underlying pathophysiologic diagnosis.

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Items

Elevated serum calcium, elevated intact PTH, decreased serum phosphorus, elevated 24-hour urine calcium
Elevated serum calcium, suppressed intact PTH, decreased serum phosphorus, elevated PTHrP
Decreased serum calcium, elevated intact PTH, increased serum phosphorus, increased BUN and creatinine
Elevated serum calcium, normal or mildly elevated intact PTH, low 24-hour urine calcium
Decreased serum calcium, suppressed intact PTH, increased serum phosphorus, normal BUN and creatinine

Matches

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Answer

1 -> Primary hyperparathyroidism; 2 -> Humoral hypercalcemia of malignancy; 3 -> Secondary hyperparathyroidism due to chronic kidney disease; 4 -> Familial hypocalciuric hypercalcemia; 5 -> Primary hypoparathyroidism.
Calcium homeostasis is maintained primarily by PTH and Vitamin D. Understanding the negative feedback loops and the specific physiologic effects of PTH (bone resorption, renal calcium reabsorption, and renal phosphate excretion) allows for the logical deduction of the underlying pathology from any given laboratory profile.

Step-by-Step Solution

1
Analyze the serum calcium and PTH levels to determine if the defect is primarily parathyroid-driven or PTH-independent.
High calcium with high PTH indicates a parathyroid-driven process (or altered calcium sensing). High calcium with low PTH indicates a PTH-independent process (e.g., malignancy). Low calcium with high PTH indicates a secondary response. Low calcium with low PTH indicates primary gland failure.
PTH and calcium normally have an inverse relationship due to negative feedback; parallel changes suggest primary parathyroid pathology.
2
Evaluate the phosphorus and renal function markers to further differentiate the etiologies.
Low phosphorus is expected with high PTH or PTHrP activity. High phosphorus with low calcium suggests either renal failure (if BUN/creatinine are high) or hypoparathyroidism (if renal function is normal).
PTH promotes renal phosphate excretion. In chronic kidney disease, the failing kidneys cannot excrete phosphate, overriding the typical PTH effect.
3
Assess urine calcium to distinguish between primary hyperparathyroidism and familial hypocalciuric hypercalcemia (FHH).
Elevated urine calcium points to primary hyperparathyroidism, whereas low urine calcium points to FHH.
FHH involves a defective calcium-sensing receptor in the kidneys, leading to increased renal calcium reabsorption despite systemic hypercalcemia.

Key Concept

Interpretation of calcium, phosphorus, and PTH laboratory profiles to diagnose underlying disorders of calcium metabolism.
Estimated Time:2m 0s
Question 1087Question →

Evaluate the following clinical scenarios of infants presenting with hyperbilirubinemia. Pair each clinical description with the most appropriate underlying diagnosis.

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Items

A 4-week-old infant presents with worsening icterus, acholic stools, and hepatomegaly. Lab work shows elevated direct bilirubin.
An exclusively breastfed 14-day-old infant is thriving and gaining weight appropriately. Total bilirubin is mildly elevated with a normal direct fraction.
A 3-day-old infant, exclusively breastfed, has lost 11% of birth weight and has decreased stooling. Total bilirubin is elevated with a normal direct fraction.
A 16-hour-old infant develops visible jaundice. The mother is blood type O positive and the infant is A positive with a positive direct antiglobulin test.

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Answer

The correct matches depend on the timing of jaundice onset, the infant's hydration and weight status, and whether the hyperbilirubinemia is conjugated (direct) or unconjugated (indirect).
Each diagnosis correlates with a unique clinical pattern. ABO incompatibility presents within 24 hours. Lactation failure presents within the first week with poor feeding and dehydration. Breast milk jaundice peaks in the second week in healthy infants. Biliary atresia uniquely presents with conjugated hyperbilirubinemia and acholic stools.

Step-by-Step Solution

1
Analyze the timing of jaundice onset.
Jaundice in the first 24 hours is pathologic (e.g., ABO incompatibility). Jaundice in the first week accompanied by weight loss is lactation failure. Jaundice peaking in the second week in a thriving infant is breast milk jaundice.
The chronologic timeline restricts the differential diagnosis for neonatal hyperbilirubinemia.
2
Evaluate the bilirubin fractionation.
Elevated direct bilirubin (conjugated) points to hepatobiliary pathology like biliary atresia, whereas elevated indirect bilirubin (unconjugated) suggests physiologic, breastfeeding-related, or hemolytic causes.
Conjugated hyperbilirubinemia is always pathologic, requiring prompt anatomic and functional investigation of the biliary tree.

Key Concept

Differential diagnosis of neonatal hyperbilirubinemia based on presentation timing, hydration status, and conjugated versus unconjugated bilirubin predominance.
Question 1088Question →

Match each of the following patient presentations, which are characterized by specific acid-base and electrolyte derangements (Left), with the precise underlying cellular or transporter defect (Right).

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Items

A 24-year-old female presents with chronic fatigue. Laboratory evaluation reveals a K+K^+ of 2.8 mEq/L, Mg2+Mg^{2+} of 1.2 mEq/L, and HCO3−HCO_3^- of 32 mEq/L. Her blood pressure is 110/70 mm Hg. A 24-hour urine collection shows a calcium-to-creatinine ratio of 0.05.
A 19-year-old male is evaluated for severe, treatment-resistant hypertension with a blood pressure of 175/110 mm Hg. Laboratories demonstrate a K+K^+ of 2.6 mEq/L and HCO3−HCO_3^- of 31 mEq/L. Both plasma renin activity and serum aldosterone concentrations are markedly suppressed.
A 38-year-old female presents with recurrent nephrolithiasis and is found to have bilateral medullary nephrocalcinosis on imaging. Laboratories show a K+K^+ of 3.1 mEq/L, Cl−Cl^- of 112 mEq/L, and HCO3−HCO_3^- of 16 mEq/L. Her fasting morning urine pHpH is 6.8.
A 55-year-old male with multiple myeloma presents with bone pain. Laboratories reveal a K+K^+ of 2.9 mEq/L and HCO3−HCO_3^- of 15 mEq/L with a normal serum anion gap. Urinalysis demonstrates significant glycosuria despite a simultaneous serum glucose of 90 mg/dL.

Matches

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Answer

The correct matches align the hypocalciuric normotensive patient with the DCT NCCT defect, the hypertensive patient with suppressed aldosterone to ENaC hyperactivity, the patient with nephrocalcinosis and alkaline urine to impaired alpha-intercalated cell H+ secretion, and the multiple myeloma patient with normoglycemic glycosuria to proximal convoluted tubule dysfunction.
Arriving at the correct diagnosis for each tubulopathy requires synthesizing the acid-base status, serum electrolytes, blood pressure, and specific urinary findings (calcium excretion, glucose, pH). Once the clinical syndrome is accurately identified, it maps precisely to a unique anatomical location and molecular transporter defect within the nephron.

Step-by-Step Solution

1
Evaluate the patient presenting with normotension, hypokalemia, metabolic alkalosis, and hypocalciuria.
Identify Gitelman syndrome, which maps to a defect in the distal convoluted tubule (NCCT).
The unique combination of salt-wasting (hypokalemia, alkalosis) with normotension and low urine calcium uniquely points to a distal convoluted tubule defect rather than a loop of Henle defect (Bartter syndrome).
2
Evaluate the patient with severe hypertension, hypokalemic metabolic alkalosis, and suppressed renin/aldosterone.
Identify Liddle syndrome, which maps to a gain-of-function mutation in ENaC.
If aldosterone is suppressed despite features of hyperaldosteronism, the defect must be constitutive activation of the downstream sodium channel in the collecting duct.
3
Evaluate the patient with a non-anion gap metabolic acidosis, hypokalemia, nephrocalcinosis, and fasting urine pH of 6.8.
Identify Type 1 (distal) RTA, which maps to defective H+ secretion by alpha-intercalated cells.
The inability to acidify urine below a pH of 5.5, combined with calcium phosphate stones, localizes the defect precisely to the distal nephron's proton pumps.
4
Evaluate the patient with multiple myeloma presenting with non-anion gap metabolic acidosis, hypokalemia, and normoglycemic glycosuria.
Identify Fanconi syndrome (Type 2 proximal RTA), which maps to generalized proximal convoluted tubule dysfunction.
Glycosuria in the absence of hyperglycemia implies a failure of the proximal tubule's Na+/glucose cotransporter, which often accompanies a failure to reabsorb bicarbonate in Fanconi syndrome.

Key Concept

Pathophysiology and localization of renal tubular defects, including renal tubular acidoses and inherited tubulopathies.
Estimated Time:3m 0s
Question 1089Question →

A hospital's antimicrobial stewardship and infectious diseases teams are reviewing several complex cases involving severe adverse drug events. Match each patient's clinical presentation of an antimicrobial-induced complication to the specific pharmacologic agent most likely responsible.

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Items

A 54-year-old man receiving intravenous therapy for right-sided methicillin-resistant Staphylococcus aureus (MRSA) endocarditis develops new-onset fever, hypoxic respiratory failure, and diffuse pulmonary infiltrates with peripheral eosinophilia.
A 36-year-old woman treated with oral therapy for a polymicrobial diabetic foot infection presents to the emergency department with severe, sudden-onset posterior ankle pain and swelling that worsened after walking.
A 45-year-old man receiving high-dose prophylaxis for Pneumocystis jirovecii is noted to have asymptomatic hyperkalemia and an elevation in serum creatinine, though his true glomerular filtration rate remains unchanged.
A 68-year-old woman on long-term oral therapy for vancomycin-resistant Enterococcus (VRE) osteomyelitis develops bilateral stocking-glove sensory loss, visual changes, and new-onset thrombocytopenia.
A 72-year-old man with chronic kidney disease receiving intravenous therapy for Pseudomonas aeruginosa pneumonia develops sudden myoclonus, encephalopathy, and non-convulsive status epilepticus.

Matches

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Answer

Eosinophilic pneumonia matches with Daptomycin. Achilles tendinopathy matches with Levofloxacin. Hyperkalemia and pseudo-kidney injury match with Trimethoprim-sulfamethoxazole. Myelosuppression and neuropathy match with Linezolid. Neurotoxicity and seizures match with Cefepime.
Each clinical vignette describes a hallmark adverse reaction to a specific antimicrobial agent used in serious infections. Daptomycin is known to cause acute eosinophilic pneumonia. Levofloxacin carries a black box warning for Achilles tendinopathy. Trimethoprim-sulfamethoxazole blocks ENaC channels causing hyperkalemia and inhibits creatinine secretion without true renal injury. Linezolid causes mitochondrial toxicity leading to cytopenias and neuropathy after prolonged use. Cefepime accumulates in renal failure, lowering the seizure threshold and causing distinct encephalopathy.

Step-by-Step Solution

1
Analyze each clinical vignette to identify the underlying infection and the specific adverse pharmacological event.
Identified toxicities: eosinophilic pneumonia, tendinopathy, hyperkalemia with pseudo-AKI, prolonged-use mitochondrial toxicity, and neurotoxicity.
Accurate identification of the syndrome is required to link it to the offending agent.
2
Correlate the identified toxicities with the antimicrobial agents known to treat the specified infections.
Daptomycin causes eosinophilic pneumonia; Levofloxacin causes tendinopathy; TMP-SMX alters potassium and creatinine handling; Linezolid causes neuropathy and cytopenias; Cefepime causes neurotoxicity in renal failure.
Antimicrobial stewardship requires monitoring for highly specific, high-yield adverse effects associated with targeted therapies.
3
Pair each clinical presentation with its definitive causative agent based on pharmacodynamic toxicity profiles.
All five distinct clinical scenarios are correctly matched to their respective antimicrobial agents.
Finalizing the matches completes the clinical evaluation.

Key Concept

Recognizing classic and severe adverse pharmacological effects of commonly used targeted antimicrobial therapies.
Question 1090Question →

Match each classic urinalysis sediment finding with its most likely associated renal pathology.

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Items

Muddy brown granular casts
Red blood cell casts
White blood cell casts
Fatty casts with a 'Maltese cross' appearance
Broad, waxy casts

Matches

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Answer

Muddy brown granular casts match with Acute tubular necrosis. Red blood cell casts match with Acute glomerulonephritis. White blood cell casts match with Acute interstitial nephritis. Fatty casts match with Nephrotic syndrome. Broad, waxy casts match with Advanced chronic kidney disease.
Each type of urinary cast has a specific mechanism of formation that correlates with a distinct pathophysiology. Muddy brown casts reflect tubular necrosis. RBC casts indicate glomerular basement membrane injury. WBC casts indicate tubulointerstitial inflammation. Fatty casts indicate lipiduria from nephrotic syndrome. Broad waxy casts indicate dilated tubules in chronic kidney disease.

Step-by-Step Solution

1
Identify the etiology of muddy brown granular casts.
Associated with acute tubular necrosis (ATN).
Ischemia or nephrotoxins cause necrosis of tubular epithelial cells, which slough off and form these characteristic casts.
2
Identify the etiology of red blood cell (RBC) casts.
Associated with acute glomerulonephritis.
RBCs escape through a damaged glomerular basement membrane and get trapped in Tamm-Horsfall mucoprotein in the tubules.
3
Identify the etiology of white blood cell (WBC) casts.
Associated with acute interstitial nephritis or pyelonephritis.
Inflammation of the interstitium and tubules leads to WBC exudation and cast formation.
4
Identify the etiology of fatty casts.
Associated with nephrotic syndrome.
Massive proteinuria stimulates hepatic lipoprotein synthesis, leading to hyperlipidemia and lipiduria, forming fatty casts.
5
Identify the etiology of broad, waxy casts.
Associated with advanced chronic kidney disease.
Chronic kidney disease leads to tubular dilation and hypertrophy; slow urine flow allows casts to form and become waxy.

Key Concept

Classic urinalysis cast findings and their specific renal etiologies
Question 1091Question →

Match each set of arterial blood gas (ABG) and basic metabolic panel (BMP) results with the most likely clinical scenario. Assume all values were obtained simultaneously on room air. Reference ranges: Na+Na^+ 135-145 mEq/L, Cl−Cl^- 98-106 mEq/L, HCO3−HCO_3^- 22-28 mEq/L, pCO2pCO_2 35-45 mmHg, pH 7.35-7.45.

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Items

pH 7.25, pCO2pCO_2 20 mmHg, HCO3−HCO_3^- 9 mEq/L, Na+Na^+ 140 mEq/L, Cl−Cl^- 105 mEq/L
pH 7.40, pCO2pCO_2 40 mmHg, HCO3−HCO_3^- 24 mEq/L, Na+Na^+ 140 mEq/L, Cl−Cl^- 96 mEq/L
pH 7.44, pCO2pCO_2 28 mmHg, HCO3−HCO_3^- 19 mEq/L, Na+Na^+ 138 mEq/L, Cl−Cl^- 108 mEq/L
pH 7.30, pCO2pCO_2 35 mmHg, HCO3−HCO_3^- 17 mEq/L, Na+Na^+ 140 mEq/L, Cl−Cl^- 115 mEq/L
pH 7.55, pCO2pCO_2 50 mmHg, HCO3−HCO_3^- 42 mEq/L, Na+Na^+ 140 mEq/L, Cl−Cl^- 90 mEq/L

Matches

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Answer

Profile 1 matches Diabetic ketoacidosis; Profile 2 matches Advanced chronic kidney disease complicated by profuse vomiting; Profile 3 matches Normal physiologic changes of third-trimester pregnancy; Profile 4 matches Severe, large-volume secretory diarrhea; and Profile 5 matches Aggressive loop diuretic therapy.
Each acid-base profile uniquely aligns with a specific clinical pathophysiology. Methodically calculating the anion gap, expected respiratory compensation, and the delta-delta ratio reveals the underlying single or mixed acid-base disorders, which are required to match the corresponding clinical scenarios accurately.

Step-by-Step Solution

1
Calculate the anion gap (AG=Na+−[Cl−+HCO3−]AG = Na^+ - [Cl^- + HCO_3^-]) for each profile to rapidly differentiate gap from non-gap metabolic acidosis.
Profile 1 (AG=26AG = 26) and Profile 2 (AG=20AG = 20) have high anion gaps. Profiles 3, 4, and 5 have normal gaps (<12< 12).
Calculating the anion gap is the essential first step in evaluating any acid-base disorder, even if the pH is entirely normal.
2
Verify appropriate respiratory compensation for primary metabolic disorders using Winter's formula (pCO2=1.5×HCO3−+8±2pCO_2 = 1.5 \times HCO_3^- + 8 \pm 2) for acidosis and the alkalosis multiplier (pCO2=0.7×ΔHCO3−+40pCO_2 = 0.7 \times \Delta HCO_3^- + 40).
Profile 1, 4, and 5 represent fully compensated primary metabolic disorders without a secondary respiratory process.
To rule out mixed respiratory-metabolic disorders in patients with clear primary metabolic derangements.
3
Calculate the delta-delta gap (ΔΔ=[AG−12]+measured HCO3−\Delta\Delta = [AG - 12] + measured\ HCO_3^-) for patients with an elevated anion gap to check for hidden mixed disorders.
For Profile 2, the adjusted HCO3−HCO_3^- is 3232 mEq/L (which is >26>26), confirming a superimposed metabolic alkalosis despite a normal measured HCO3−HCO_3^-.
A high anion gap always represents a metabolic acidosis; a normal pH and HCO3−HCO_3^- in this setting guarantees the presence of a neutralizing metabolic alkalosis.

Key Concept

Acid-base interpretation utilizing the anion gap, expected respiratory compensation, and delta-delta gap.
Question 1092Question →

Evaluate the following clinical scenarios describing neonates who experienced complications related to the birth process. Match each clinical presentation with its correct underlying anatomical or pathophysiological mechanism.

Click a left item, then click its matching right item

Items

A 2-hour-old neonate born via vacuum-assisted delivery develops a rapidly expanding, fluctuant scalp swelling that crosses suture lines, accompanied by persistent tachycardia and pallor.
A 24-hour-old neonate born via forceps delivery is noted to have a firm, localized scalp swelling confined entirely to the right parietal bone without crossing the sagittal suture.
A neonate examined immediately after a prolonged vaginal delivery has a soft, boggy, pitting swelling over the vertex that crosses suture lines and resolves spontaneously by day 2.
A 4.5-kg neonate born after shoulder dystocia holds the right arm adducted and internally rotated with the elbow extended; the grasp reflex is intact, but the Moro reflex is asymmetric.
A neonate born via breech extraction presents with an absent grasp reflex in the left hand, along with left-sided ptosis and miosis.

Matches

Show answer & explanation

Answer

The correct matches pair subgaleal hemorrhage with emissary vein rupture, cephalohematoma with subperiosteal vessel rupture, caput succedaneum with subcutaneous fluid accumulation, Erb palsy with C5-C6 traction, and Klumpke palsy with C8-T1 traction.
Each clinical scenario corresponds to a distinct anatomical injury incurred during delivery. Subgaleal hemorrhage involves the subgaleal space (emissary veins) and is characterized by a fluctuant, crossing mass with hypovolemia. Cephalohematoma involves the subperiosteal space, presenting as a firm, non-crossing mass. Caput succedaneum is benign subcutaneous edema. Erb palsy is an upper trunk (C5-C6) injury resulting in an adducted, internally rotated arm with an intact grasp. Klumpke palsy is a lower trunk (C8-T1) injury presenting with a claw hand (absent grasp) and potential Horner syndrome.

Step-by-Step Solution

1
Analyze each clinical vignette to identify the specific type of birth trauma.
Identified Subgaleal Hemorrhage (Scenario 1), Cephalohematoma (Scenario 2), Caput Succedaneum (Scenario 3), Erb-Duchenne Palsy (Scenario 4), and Klumpke Palsy (Scenario 5).
Accurate clinical pattern recognition is required before determining the underlying etiology.
2
Determine the precise anatomical location and pathophysiological mechanism of the identified birth traumas.
Linked the scalp swellings to their specific anatomical layers (subgaleal space, subperiosteal space, subcutaneous tissue) and the nerve palsies to their specific spinal roots (C5-C6 vs. C8-T1).
Standardizing the mechanism allows for accurate matching with the provided anatomical descriptions.
3
Map the derived mechanisms to the options provided in the right-hand list.
Completed the pairings based on the anatomical and nerve root correlations.
Finalizes the matching process.

Key Concept

Neonatal birth trauma mechanisms and anatomical localization
Question 1093Question →

A medical student is reviewing laboratory data for five different patients evaluated in the endocrinology clinic for suspected calcium and bone metabolism disorders. Based on the diagnostic algorithm for calcium homeostasis, match each of the following complex laboratory profiles to its most likely underlying pathophysiologic diagnosis.

Click a left item, then click its matching right item

Items

High Serum Calcium, Low Serum Phosphorus, High Intact PTH, High 24-hour Urinary Calcium
Low Serum Calcium, High Serum Phosphorus, High Intact PTH, Low 1,25-dihydroxyvitamin D
High Serum Calcium, Low Serum Phosphorus, Suppressed Intact PTH, High PTH-related peptide (PTHrP)
High Serum Calcium, High Serum Phosphorus, Suppressed Intact PTH, High 1,25-dihydroxyvitamin D
Mildly High Serum Calcium, Normal Serum Phosphorus, Normal to mildly High Intact PTH, Very Low 24-hour Urinary Calcium

Matches

Show answer & explanation

Answer

Profile 1 matches Primary hyperparathyroidism. Profile 2 matches Secondary hyperparathyroidism. Profile 3 matches Humoral hypercalcemia of malignancy. Profile 4 matches Granulomatous disease. Profile 5 matches Familial hypocalciuric hypercalcemia (FHH).
Each laboratory profile uniquely aligns with the pathophysiology of a distinct disease state. High calcium with high PTH signifies a failure of negative feedback at the parathyroid gland (Primary HPT) or altered sensing setpoints (FHH). High calcium with suppressed PTH implies an external driver, such as PTHrP from a tumor or uncontrolled calcitriol production from granulomas. Low calcium with high phosphorus and PTH points to a failing kidney unable to excrete phosphate or activate vitamin D.

Step-by-Step Solution

1
Separate the profiles based on the serum calcium level.
Profile 2 shows hypocalcemia, while Profiles 1, 3, 4, and 5 show hypercalcemia.
Identifying whether the primary derangement is hypercalcemia or hypocalcemia dictates the subsequent diagnostic algorithm.
2
Diagnose the hypocalcemic profile.
Profile 2 matches Secondary hyperparathyroidism due to chronic kidney disease.
The combination of high phosphorus, low active vitamin D, and low calcium with compensatory high PTH is the classic biochemical signature of renal failure.
3
Divide the hypercalcemic profiles based on the intact PTH level.
Profiles 1 and 5 have elevated/unsuppressed PTH (PTH-dependent). Profiles 3 and 4 have suppressed PTH (PTH-independent).
A suppressed PTH correctly indicates a non-parathyroid driver of hypercalcemia, whereas an unsuppressed PTH suggests parathyroid pathology or altered calcium sensing.
4
Differentiate the PTH-dependent hypercalcemias using 24-hour urinary calcium.
Profile 1 (high urine calcium) is Primary hyperparathyroidism. Profile 5 (very low urine calcium) is Familial hypocalciuric hypercalcemia.
FHH features a mutated CaSR that promotes renal calcium retention, yielding hypocalciuria, which distinguishes it from the hypercalciuria typically seen in primary hyperparathyroidism.
5
Differentiate the PTH-independent hypercalcemias using specific markers (PTHrP vs. 1,25-Vit D).
Profile 3 (high PTHrP) is Humoral hypercalcemia of malignancy. Profile 4 (high 1,25-Vit D) is Granulomatous disease.
Malignancies secrete PTHrP directly mimicking PTH effects without activating vitamin D, whereas sarcoidosis macrophages autonomously activate vitamin D, increasing both calcium and phosphorus.

Key Concept

Diagnosis of calcium metabolism disorders relies on evaluating serum calcium in tandem with intact PTH, followed by specific markers like phosphorus, 1,25-dihydroxyvitamin D, PTHrP, and 24-hour urinary calcium to isolate the precise etiology.
Question 1094Question →

Match each laboratory profile with its most likely underlying pathophysiologic diagnosis. Assume normal reference ranges for the following: Serum calcium 8.4-10.2 mg/dL, Phosphorus 2.5-4.5 mg/dL, Intact PTH 15-65 pg/mL.

Click a left item, then click its matching right item

Items

Serum calcium: 12.8 mg/dL, Phosphorus: 2.1 mg/dL, Intact PTH: 8 pg/mL
Serum calcium: 10.9 mg/dL, Phosphorus: 2.4 mg/dL, Intact PTH: 115 pg/mL
Serum calcium: 7.2 mg/dL, Phosphorus: 6.8 mg/dL, Intact PTH: 410 pg/mL
Serum calcium: 7.6 mg/dL, Phosphorus: 2.0 mg/dL, Intact PTH: 195 pg/mL

Matches

Show answer & explanation

Answer

Profile 1 matches Humoral hypercalcemia of malignancy. Profile 2 matches Primary hyperparathyroidism. Profile 3 matches Chronic kidney disease. Profile 4 matches Vitamin D deficiency.
Each underlying diagnosis produces a distinct, predictable pattern of calcium, phosphorus, and parathyroid hormone (PTH) alterations based on physiologic feedback loops. Primary hyperparathyroidism drives high calcium and low phosphorus. Malignancy drives high calcium (suppressing native PTH) and low phosphorus (due to PTHrP). CKD causes low calcium and high phosphorus due to renal failure, triggering high PTH. Vitamin D deficiency causes low calcium and low phosphorus, also triggering high PTH.

Step-by-Step Solution

1
Analyze the serum calcium level to categorize the primary derangement as hypercalcemia or hypocalcemia.
Profiles 1 and 2 display hypercalcemia, while profiles 3 and 4 display hypocalcemia.
This initial categorization restricts the differential diagnosis to specific subsets of metabolic bone and mineral disorders.
2
Evaluate the intact PTH level relative to the serum calcium to determine if the parathyroid response is appropriate.
In Profile 1, PTH is appropriately suppressed (< 15 pg/mL), indicating a PTH-independent cause of hypercalcemia. In Profile 2, PTH is inappropriately elevated, indicating primary parathyroid pathology. In Profiles 3 and 4, PTH is appropriately elevated in response to hypocalcemia (secondary hyperparathyroidism).
The intact PTH assay is the most reliable tool to differentiate primary hyperparathyroidism from other causes of hypercalcemia, and to confirm an appropriate physiologic response to hypocalcemia.
3
Use the serum phosphorus level to distinguish between the two causes of secondary hyperparathyroidism (Profiles 3 and 4).
Profile 3 shows marked hyperphosphatemia, pointing to chronic kidney disease where the failing kidneys cannot excrete phosphate. Profile 4 shows hypophosphatemia, pointing to vitamin D deficiency where the elevated PTH successfully causes renal phosphate wasting.
Renal function dictates whether the phosphaturic effect of elevated PTH can be achieved.

Key Concept

Interpretation of paired calcium, phosphorus, and PTH laboratory profiles to differentiate between primary, secondary, and PTH-independent disturbances of mineral metabolism.
Question 1095Question →

Match each patient's clinical presentation with the most likely histopathologic or defining structural finding associated with their underlying condition.

Click a left item, then click its matching right item

Items

A 72-year-old woman with a new-onset severe unilateral headache, pain in her jaw muscles when chewing, and an episode of transient monocular vision loss.
A 45-year-old man with recent-onset testicular pain, severe postprandial abdominal pain, and right-sided wrist drop; serologies are negative for ANCA.
A 38-year-old man with a history of recurrent sinusitis presenting with hemoptysis, saddle-nose deformity, and hematuria with red blood cell casts.
A 7-year-old boy presenting with palpable purpura on the lower extremities, intermittent colicky abdominal pain, and knee arthralgias following a viral infection.

Matches

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Answer

Giant Cell Arteritis matches with granulomatous inflammation and elastic lamina fragmentation. Polyarteritis Nodosa matches with transmural necrotizing inflammation of medium arteries. Granulomatosis with Polyangiitis matches with necrotizing granulomatous small vessel inflammation. IgA Vasculitis matches with IgA/C3 leukocytoclastic vasculitis.
Systemic vasculitides are classified by the primary size of the blood vessels affected and their underlying histopathology. The older woman presents with classic Giant Cell Arteritis, a large-vessel condition characterized by granulomatous inflammation and elastic lamina fragmentation. The middle-aged man displays features of Polyarteritis Nodosa, a medium-vessel disease leading to microaneurysms and tissue ischemia (sparing the lungs). The young man with the saddle-nose deformity has Granulomatosis with Polyangiitis, uniquely presenting with upper/lower respiratory granulomas and renal disease. Finally, the child has IgA Vasculitis, driven by immune complex deposition in small vessels.

Step-by-Step Solution

1
Evaluate the 72-year-old woman's symptoms (jaw claudication, vision loss, headache)
Identify Giant Cell Arteritis (GCA)
These are hallmark features of a large-vessel vasculitis affecting branches of the carotid artery, classically confirmed via temporal artery biopsy.
2
Evaluate the 45-year-old man's symptoms (testicular pain, abdominal angina, mononeuritis multiplex)
Identify Polyarteritis Nodosa (PAN)
These features reflect ischemia in distinct vascular beds supplied by medium-sized arteries, without lung involvement, which defines PAN.
3
Evaluate the 38-year-old man's symptoms (sinusitis, hemoptysis, hematuria)
Identify Granulomatosis with Polyangiitis (GPA)
The combination of upper and lower respiratory tract necrotizing granulomas alongside rapidly progressive glomerulonephritis is pathognomonic for GPA.
4
Evaluate the 7-year-old boy's symptoms (palpable purpura, abdominal pain, arthralgias)
Identify IgA Vasculitis (Henoch-Schönlein purpura)
This is the classic presentation of systemic IgA-mediated small-vessel vasculitis in childhood, often triggered by an upper respiratory infection.

Key Concept

Correlation of clinical presentations with histopathologic findings across large, medium, and small vessel systemic vasculitides.
Estimated Time:1m 30s
Question 1096Question →

Match each clinical scenario to the most appropriate first-line antimicrobial therapy.

Click a left item, then click its matching right item

Items

A 34-year-old man from Arkansas with fever, leukopenia, thrombocytopenia, and elevated transaminases following a tick bite.
A 25-year-old pregnant woman in her first trimester with an expanding, erythematous, targetoid rash on her thigh after hiking in Connecticut.
A 40-year-old man presenting with rapidly progressive erythema, swelling, and intense pain at the site of a deep puncture wound from a cat on his hand.
A 50-year-old man with a history of splenectomy presenting with fever, hemolytic anemia, thrombocytopenia, and intraerythrocytic tetrads on blood smear.
A 35-year-old man with advanced HIV presenting with progressive headache, fever, and a positive cerebrospinal fluid cryptococcal antigen test.

Matches

Show answer & explanation

Answer

Properly match the infectious pathogen to its targeted or empiric therapy: Ehrlichiosis to doxycycline, Lyme disease in pregnancy to amoxicillin, Pasteurella to amoxicillin-clavulanate, Babesiosis to atovaquone and azithromycin, and Cryptococcal meningitis to amphotericin B and flucytosine.
Each clinical scenario requires recognizing the likely pathogen based on exposure history, clinical signs, and laboratory findings, then matching it to the established first-line antimicrobial therapy according to current guidelines.

Step-by-Step Solution

1
Analyze the tick-borne illness with cytopenias.
Identified as human monocytic ehrlichiosis.
Allows selection of doxycycline as the preferred agent.
2
Evaluate the expanding rash in a pregnant hiker.
Diagnosed as Lyme disease (erythema migrans) in pregnancy.
Doxycycline is teratogenic, so amoxicillin is chosen instead.
3
Review the animal bite scenario.
Identified as a high-risk cat bite prone to Pasteurella infection.
Requires amoxicillin-clavulanate for adequate anaerobic and Pasteurella coverage.
4
Interpret the blood smear in the asplenic patient.
Identified tetrads as indicative of Babesia infection.
Directs the specific antiprotozoal therapy of atovaquone and azithromycin.
5
Identify the cause of meningitis in the HIV patient.
Diagnosed as cryptococcal meningitis based on antigen test.
Necessitates induction therapy with amphotericin B and flucytosine.

Key Concept

Appropriate selection of antimicrobial therapy requires identifying the most likely pathogen and considering patient-specific factors such as pregnancy or immune status.
Question 1097Question →

Match each clinical presentation of a patient experiencing an adverse event during or shortly after a packed red blood cell (pRBC) transfusion to the most likely underlying pathophysiologic mechanism.

Click a left item, then click its matching right item

Items

A 68-year-old man with a history of ischemic cardiomyopathy develops progressive dyspnea, a blood pressure of 185/105 mm Hg, and a prominent S3 gallop two hours into receiving a pRBC transfusion.
A 52-year-old woman undergoing an exploratory laparotomy develops sudden diffuse oozing from the surgical field, dark urine, and a blood pressure drop to 70/40 mm Hg 10 minutes after initiation of a pRBC transfusion.
A 40-year-old man being treated for a severe gastrointestinal hemorrhage develops acute severe hypoxemia, new bilateral pulmonary infiltrates, and a blood pressure of 85/50 mm Hg three hours after receiving a pRBC transfusion.
A 35-year-old man with acute myeloid leukemia develops a new-onset temperature of 39.2°C (102.6°F) and rigors 45 minutes into a pRBC transfusion, while maintaining normal blood pressure and oxygen saturation.

Matches

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Answer

The correct pairings successfully match TACO to volume expansion (left 1 to right 1), AHTR to ABO incompatibility with complement activation (left 2 to right 2), TRALI to donor antibodies activating recipient neutrophils (left 3 to right 3), and FNHTR to cytokine/leukocyte reactions (left 4 to right 4).
Each correct pairing links the distinct constellation of vital signs and physical exam findings to the exact immunologic or hemodynamic mechanism driving the transfusion reaction, correctly distinguishing between the hypertensive presentation of TACO, the hypotensive presentation of TRALI, the coagulopathic presentation of AHTR under anesthesia, and the isolated febrile presentation of FNHTR.

Step-by-Step Solution

1
Analyze the timeline and specific vital sign changes in each clinical vignette.
Distinguish between immediate, life-threatening reactions (shock, DIC) and delayed or milder reactions (isolated fever, respiratory distress).
Onset time and hemodynamic status are key diagnostic branch points for evaluating transfusion reactions.
2
Differentiate the two primary causes of acute pulmonary edema following a transfusion.
The 68-year-old man presents with hypertension and an S3 gallop, indicating TACO. The 40-year-old man presents with hypotension and no prior cardiac history, indicating TRALI.
TACO is a cardiogenic volume overload state characterized by hypertension, whereas TRALI is an immune-mediated capillary leak state characterized by hypotension.
3
Identify the presentation of severe acute hemolysis in an anesthetized patient.
The 52-year-old woman shows diffuse oozing and dark urine (hemoglobinuria), indicative of DIC and intravascular hemolysis characteristic of AHTR.
Anesthesia masks typical symptoms like flank pain and fever, making coagulopathy and shock the predominant presenting signs of ABO incompatibility in the operating room.
4
Isolate the uncomplicated febrile presentation.
The 35-year-old man has a fever and rigors without other systemic compromise, diagnosing FNHTR.
Unlike AHTR or TRALI, FNHTR is a self-limiting reaction driven by cytokines and does not cause hemodynamic collapse or respiratory failure.

Key Concept

Pathophysiology and clinical presentation of acute blood transfusion reactions.
Question 1098Question →

A physician is evaluating an adult patient with newly diagnosed, severe, and resistant hypertension. The physician considers various secondary causes based on the patient's history and subtle physical exam clues. Match each suspected secondary cause of hypertension with its most appropriate initial screening test.

Click a left item, then click its matching right item

Items

Primary hyperaldosteronism
Pheochromocytoma
Renovascular hypertension
Cushing syndrome

Matches

Show answer & explanation

Answer

Primary hyperaldosteronism matches with the aldosterone-to-renin ratio. Pheochromocytoma matches with plasma metanephrines. Renovascular hypertension matches with renal ultrasound. Cushing syndrome matches with the dexamethasone suppression test.
Each secondary cause of hypertension is paired with its guideline-recommended initial screening test. Screening tests are chosen for their high sensitivity to rule out the condition. The PAC/PRA ratio detects autonomous aldosterone; plasma metanephrines detect catecholamine breakdown; duplex ultrasound visualizes renal artery stenosis; and the low-dose dexamethasone test identifies a failure to suppress endogenous cortisol production.

Step-by-Step Solution

1
Identify the underlying pathophysiology of each secondary hypertension cause.
Recognize that primary hyperaldosteronism involves aldosterone excess, pheochromocytoma involves catecholamine excess, renovascular disease involves impaired renal perfusion, and Cushing syndrome involves cortisol excess.
Understanding the pathophysiologic mechanism dictates which hormone or organ system needs to be evaluated.
2
Select the most appropriate, sensitive, and least invasive initial screening modality for each condition.
Match each condition to its standard initial diagnostic test according to current clinical guidelines.
Accurate initial screening is required to select patients who need further, often more invasive, confirmatory testing.

Key Concept

Initial diagnostic screening tests for secondary causes of hypertension.
Estimated Time:1m 0s
Question 1099Question →

Match the following clinical etiologies with their classic presentation on a serum electrolyte panel.

Click a left item, then click its matching right item

Items

Primary adrenal insufficiency
Severe diarrhea
Loop diuretic use
Primary hyperaldosteronism

Matches

Show answer & explanation

Answer

Primary adrenal insufficiency pairs with hyponatremia/hyperkalemia/acidosis; Severe diarrhea pairs with hypokalemia/acidosis; Loop diuretic use pairs with hypokalemia/hypomagnesemia/alkalosis; Primary hyperaldosteronism pairs with hypernatremia/hypokalemia/alkalosis.
Each clinical condition alters renal tubular transport or gastrointestinal losses in specific ways that predictably change serum sodium, potassium, and acid-base balance based on their underlying mechanism of action.

Step-by-Step Solution

1
Analyze the effects of primary adrenal insufficiency on electrolytes.
Identified that lack of aldosterone causes sodium wasting, potassium retention, and acid retention.
Aldosterone normally reabsorbs sodium and secretes potassium and hydrogen ions in the collecting duct; its absence reverses this.
2
Analyze the effects of severe diarrhea on electrolytes.
Identified that diarrhea causes loss of bicarbonate and potassium.
Lower gastrointestinal secretions are rich in potassium and bicarbonate, leading to a non-anion gap acidosis and hypokalemia when lost.
3
Analyze the effects of loop diuretics on electrolytes.
Identified that they cause loss of potassium, magnesium, and hydrogen ions (alkalosis).
Inhibition of the Na-K-2Cl cotransporter reduces the lumen-positive potential, decreasing paracellular magnesium reabsorption, while increased distal delivery of sodium stimulates potassium and hydrogen secretion.
4
Analyze the effects of primary hyperaldosteronism on electrolytes.
Identified that excess aldosterone causes sodium retention, potassium loss, and hydrogen loss.
Unregulated aldosterone hypersecretion continually drives ENaC channels and apical potassium/hydrogen pumps in the distal nephron.

Key Concept

Pathophysiology of acid-base and electrolyte disturbances
Question 1100Question →

Review the clinical vignettes below, representing adult patients currently undergoing psychiatric evaluation for mood symptoms. Map each individual's unique presentation to the most appropriate initial pharmacological or procedural intervention.

Click a left item, then click its matching right item

Items

A 42-year-old man hospitalized for profound despair, psychomotor agitation, and mood-congruent auditory hallucinations telling him he is 'corrupted from the inside.' He is medically stable, cooperative with nursing staff, and eating adequately.
A 68-year-old man transferred from an assisted living facility due to a 10-day history of mutism, stupor, and absolute refusal to ingest food or fluids, which has now resulted in acute prerenal azotemia and severe dehydration.
A 24-year-old woman with a two-month history of sleeping 14 hours daily, intense carbohydrate cravings, weight gain, and 'leaden' fatigue. She strongly desires medication but specifically requests an option that avoids sexual side effects.
A 28-year-old woman presenting 4 weeks after an uncomplicated vaginal delivery with pervasive anhedonia, insomnia despite infant sleep, and extreme tearfulness. She is exclusively breastfeeding her newborn infant.

Matches

Show answer & explanation

Answer

The correct pairings map the medically stable psychotic depression to combined antidepressant/antipsychotic therapy; the life-threatening catatonic depression to ECT; the atypical depression with sexual side-effect concerns to bupropion; and the postpartum depression in a lactating mother to sertraline.
Each correct match strictly aligns with psychiatric treatment guidelines: psychotic features require dual therapy (antidepressant + antipsychotic); severe medical compromise (starvation/dehydration) mandates the rapid, definitive efficacy of ECT; atypical symptoms with an aversion to sexual dysfunction perfectly fit the profile for bupropion; and lactation requires medications with negligible breast milk excretion, like sertraline.

Step-by-Step Solution

1
Analyze each patient's presenting symptoms to identify the specific depressive subtype or modifying clinical circumstance.
Identified psychotic features, life-threatening catatonia, atypical features with specific side-effect requests, and the postpartum/lactating state.
Major depressive disorder is heterogeneous; treatment choice heavily relies on recognizing these specific modifiers.
2
Select the evidence-based first-line treatment corresponding to each clinical modifier.
Matched each presentation to its respective guideline-directed therapy (e.g., ECT for acute life-threatening situations, Sertraline for lactation safety).
Ensures the chosen intervention maximizes efficacy while minimizing harm for the specific demographic or symptomatic presentation.

Key Concept

Treatment selection for major depressive disorder subtypes and special populations
Estimated Time:1m 30s
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