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Patient Management

2074 questions

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Question 601Question →

A 50-year-old man is treated in the intensive care unit for massive hematemesis. He has a history of severe alcohol use disorder and decompensated cirrhosis. Upon admission, he was tachycardic and hypotensive, requiring prompt endotracheal intubation for airway protection. He has been receiving aggressive resuscitation with intravenous crystalloids, matched packed red blood cells, continuous octreotide infusion, and prophylactic ceftriaxone. An urgent esophagogastroduodenoscopy was attempted but aborted; pooling blood completely obscured the visualization of the esophageal mucosa, precluding any endoscopic band ligation or sclerotherapy. Currently, his blood pressure is 78/48 mm Hg and his heart rate is 132/min. The critical care team determines that a transjugular intrahepatic portosystemic shunt (TIPS) is indicated, but the interventional radiology team states that the procedure cannot be initiated for another 90 minutes. Which of the following is the most appropriate immediate procedural intervention for this patient?

Show answer & explanation

Answer: Placement of a temporary balloon tamponade tube

Answer

Placement of a temporary balloon tamponade tube
In the management of acute variceal hemorrhage, first-line treatment includes hemodynamic resuscitation, prophylactic antibiotics (e.g., ceftriaxone), splanchnic vasoconstrictors (e.g., octreotide), and urgent endoscopic therapy (e.g., band ligation). However, in up to 10-20% of cases, endoscopy fails due to massive pooling of blood obscuring the visual field. When initial medical and endoscopic therapies fail, the patient requires a salvage procedure, typically a transjugular intrahepatic portosystemic shunt (TIPS). Because TIPS requires specialized personnel and an interventional radiology suite, it may not be immediately available. In these catastrophic, life-threatening situations, placement of a temporary balloon tamponade tube (such as a Sengstaken-Blakemore or Minnesota tube) is the most appropriate immediate procedural intervention. The inflated gastric and esophageal balloons exert direct mechanical pressure against the bleeding varices, achieving temporary hemostasis. This serves as a critical bridge to stabilize the patient until TIPS can be performed. Balloon tamponade is strictly a temporary measure (maximum 24 hours) due to the high risk of esophageal ulceration and necrosis.

Step-by-Step Solution

1
Assess the clinical scenario and patient stability.
The patient is actively exsanguinating from suspected esophageal varices and is profoundly hypotensive (BP 78/48 mm Hg) despite aggressive medical resuscitation.
Recognizing the severity dictates the immediate need for mechanical or surgical hemostasis rather than further diagnostic delay.
2
Evaluate the outcomes of initial standard therapies.
First-line therapies, including octreotide, antibiotics, and attempted esophagogastroduodenoscopy, have failed to control the hemorrhage due to poor visualization.
Failed primary therapies require immediate escalation to salvage interventions according to the variceal hemorrhage algorithm.
3
Determine the appropriate bridge to definitive therapy.
Since the definitive salvage procedure (TIPS) is delayed by 90 minutes, a temporary balloon tamponade tube must be placed immediately.
Balloon tamponade provides direct physical compression to the bleeding varices, stabilizing the patient hemodynamically while awaiting the interventional radiology team.

Key Concept

Management of refractory acute variceal hemorrhage
Estimated Time:1m 30s
Question 602Question →

A 74-year-old woman is evaluated in the emergency department for sudden, severe, diffuse abdominal pain that began 4 hours ago. She has a history of paroxysmal atrial fibrillation, type 2 diabetes mellitus, and chronic kidney disease. She recently stopped taking her apixaban due to financial constraints. On presentation, her temperature is 38.2°C (100.8°F), blood pressure is 82/50 mm Hg, pulse is 128/min and irregularly irregular, and respirations are 24/min. Physical examination reveals a rigid, distended abdomen with diffuse rebound tenderness and involuntary guarding. Laboratory studies show a leukocyte count of 22,000/mm³ and serum lactate of 8.4 mmol/L (Normal: 0.5-2.2 mmol/L). Aggressive intravenous fluid resuscitation and broad-spectrum antibiotics are initiated.

Which of the following procedural and surgical interventions are definitively indicated in the management of this patient? (Select all that apply)

Select all that apply

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Answer: Emergent open exploratory laparotomy; Surgical embolectomy of the superior mesenteric artery

Answer

The correct interventions are emergent open exploratory laparotomy AND surgical embolectomy of the superior mesenteric artery.
The correct interventions focus on immediate life-saving surgery. The patient's history of unanticoagulated atrial fibrillation combined with sudden-onset abdominal pain strongly suggests acute embolic superior mesenteric artery (SMA) occlusion. The subsequent development of peritonitis (rigidity, rebound guarding), shock (hypotension, tachycardia), and severe lactic acidosis indicates transmural bowel infarction. In the setting of peritonitis and hemodynamic instability, emergent open exploratory laparotomy is the absolute mandatory next step to resect dead tissue. Concurrently, surgical embolectomy of the SMA must be performed to restore perfusion to the remaining viable bowel. Delaying for imaging or attempting medical/endovascular salvage in the presence of peritonitis is inappropriate.

Step-by-Step Solution

1
Analyze the patient's presentation and history.
The patient has sudden, severe abdominal pain, atrial fibrillation off anticoagulation, hypotension, and a high lactate.
This constellation of findings is classic for acute embolic mesenteric ischemia.
2
Evaluate the physical examination findings.
The patient has a rigid, distended abdomen with rebound tenderness and guarding.
These findings indicate peritonitis, which signifies transmural bowel infarction and impending or actual perforation.
3
Determine the appropriate sequence of interventions.
The patient requires an immediate emergent exploratory laparotomy.
Hemodynamic instability combined with peritonitis is an absolute indication for emergent surgical exploration. Imaging (e.g., CT angiography) must be bypassed to avoid fatal delays.
4
Identify the necessary intraoperative procedures.
Surgical embolectomy of the superior mesenteric artery is required.
To salvage any ischemic but viable bowel, blood flow must be restored by removing the embolus before or during the resection of frankly necrotic segments.

Key Concept

In patients with acute mesenteric ischemia, the development of peritonitis or hemodynamic instability mandates emergent exploratory laparotomy and restoration of mesenteric blood flow (e.g., surgical embolectomy). Preoperative advanced imaging and primary bowel anastomosis are strictly contraindicated in this setting.
Question 603Question →

A 71-year-old man is brought to the emergency department after a sudden onset of severe headache, right-sided weakness, and expressive aphasia. He has a history of nonvalvular atrial fibrillation, hypertension, and type 2 diabetes mellitus. His daily medications include apixaban, lisinopril, and metformin. On arrival, his blood pressure is 185/105 mm Hg185/105 \text{ mm Hg}. A non-contrast CT scan of the head reveals a large left basal ganglia intracerebral hemorrhage. His blood pressure is promptly managed with an intravenous nicardipine infusion. Due to his life-threatening bleeding and confirmed recent apixaban use, an intravenous bolus followed by a 2-hour infusion of andexanet alfa is administered.

One hour after the completion of the andexanet alfa infusion, the patient's neurological examination remains unchanged from presentation. A repeat head CT shows no expansion of the hematoma. The intensive care team orders a chromogenic anti-factor Xa activity level (calibrated for apixaban) to evaluate the success of the reversal therapy. The result is 1.8 IU/mL1.8 \text{ IU/mL} (therapeutic range for stroke prevention: 1.0−2.0 IU/mL1.0 - 2.0 \text{ IU/mL}), suggesting high residual apixaban activity.

Which of the following is the most appropriate next step in the monitoring and treatment evaluation of this patient?

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Answer: Withhold further pharmacologic reversal agents and continue close clinical and radiographic monitoring

Answer

Withhold further pharmacologic reversal agents and continue close clinical and radiographic monitoring
The correct response is to withhold further pharmacologic reversal agents and continue close clinical and radiographic monitoring. Andexanet alfa is a recombinant modified human factor Xa decoy protein that binds factor Xa inhibitors like apixaban with high affinity, neutralizing their anticoagulant effect. However, the binding is reversible. When a patient's plasma is sent for a commercial chromogenic anti-factor Xa activity assay, the laboratory protocol requires significant sample dilution. This dilution alters the binding equilibrium, causing the andexanet-apixaban complex to dissociate in the test tube. The newly freed apixaban then inhibits the factor Xa reagent used in the assay, producing a falsely high anti-factor Xa activity level. Because this laboratory result is an in vitro artifact that completely misrepresents the patient's reversed in vivo coagulation status, treatment evaluation following andexanet alfa administration must rely exclusively on objective clinical markers (e.g., neurological exam stability) and radiographic evidence (e.g., lack of hematoma expansion). Administering further reversal agents or blood products based on this false lab value places the patient at extreme risk for fatal thrombotic events.

Step-by-Step Solution

1
Analyze the clinical scenario and the initial intervention.
The patient presented with a life-threatening intracerebral hemorrhage while on apixaban. He correctly received andexanet alfa, a specific reversal agent for factor Xa inhibitors. His clinical and radiographic status has subsequently stabilized.
Establishing the baseline effectiveness of the initial management is required before interpreting follow-up data.
2
Evaluate the laboratory finding (anti-factor Xa activity of 1.8 IU/mL1.8 \text{ IU/mL}) in the context of recent andexanet alfa administration.
The laboratory value suggests therapeutic levels of apixaban remain, but this conflicts with the stabilized clinical picture.
Discrepancies between clinical status and laboratory values must prompt an evaluation for assay interference or physiological variables.
3
Apply pharmacological knowledge regarding post-reversal monitoring.
Andexanet alfa binds apixaban reversibly. The high sample dilution required in standard commercial chromogenic anti-factor Xa assays causes the complex to dissociate in vitro, releasing apixaban and yielding a falsely elevated anti-Xa level that does not reflect in vivo coagulation status.
Understanding the pharmacokinetic limitations of common laboratory assays prevents dangerous clinical misjudgments.
4
Determine the best next step in management.
Because the laboratory value is artifactual and the patient is clinically and radiographically stable, no additional reversal or clearance therapy is indicated. Standard supportive care should continue.
Overtreatment based on a false laboratory value introduces unnecessary, potentially fatal thrombotic risk.

Key Concept

Commercial chromogenic anti-factor Xa assays exhibit significant interference following andexanet alfa administration, causing falsely elevated measurements of residual apixaban or rivaroxaban activity. Treatment evaluation and monitoring must therefore rely exclusively on clinical and radiographic parameters.
Question 604Question →

A 32-year-old woman presents to the outpatient clinic with a two-day history of dysuria, increased urinary frequency, and suprapubic discomfort. She has no fever, chills, or flank pain. Her last menstrual period was 10 weeks ago, and a urine pregnancy test performed in the clinic is positive. Vital signs are within normal limits. Physical examination reveals mild suprapubic tenderness but no costovertebral angle tenderness. Urinalysis is positive for leukocyte esterase, nitrites, and bacteria. The patient has no known drug allergies. Which of the following is the most appropriate empiric pharmacologic intervention for this patient?

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Answer: Oral cephalexin

Answer

Oral cephalexin
The correct answer is an oral first-generation cephalosporin. In pregnant patients, beta-lactam antibiotics (such as cephalexin, amoxicillin-clavulanate, and cefpodoxime) are considered safe and represent first-line empiric therapy for uncomplicated urinary tract infections. Cephalexin provides adequate coverage for Escherichia coli and other common uropathogens while posing no known teratogenic risks to the developing fetus.

Step-by-Step Solution

1
Diagnose the clinical condition.
The patient has acute uncomplicated cystitis.
Symptoms of dysuria, frequency, and suprapubic pain with positive urinalysis indicate a lower urinary tract infection.
2
Identify key patient constraints.
The patient is in her first trimester of pregnancy (10 weeks gestation).
Pregnancy status strictly limits the use of several common antimicrobial classes due to teratogenic risks.
3
Select the safest, most effective antimicrobial agent.
Beta-lactam antibiotics, such as cephalexin, are selected.
Beta-lactams have a well-established safety profile in pregnancy and provide adequate coverage against typical uropathogens like Escherichia coli.

Key Concept

Empiric antimicrobial selection for urinary tract infections during pregnancy
Estimated Time:1m 0s
Question 605Question →

Match each clinical vignette describing a patient awaiting hospital discharge to the most appropriate post-acute care disposition setting.

Click a left item, then click its matching right item

Items

A 78-year-old with a recent stroke requiring daily physical therapy who fatigues after 15 to 20 minutes of exertion.
A 55-year-old recovering from multiple pelvic fractures who needs intensive physical and occupational therapy and easily tolerates 3.5 hours of daily therapy.
A 65-year-old with resolving acute respiratory distress syndrome who remains dependent on a tracheostomy and mechanical ventilation, requiring a prolonged weaning protocol.
An 88-year-old with end-stage chronic obstructive pulmonary disease who has declined further hospitalizations or intubation, preferring to maximize comfort at home.

Matches

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Answer

The stroke patient with low therapy tolerance matches to a Skilled Nursing Facility. The trauma patient with high therapy tolerance matches to an Inpatient Rehabilitation Facility. The patient requiring prolonged mechanical ventilation weaning matches to a Long-Term Acute Care Hospital. The patient with end-stage disease focusing on comfort matches to Home Hospice Care.
Post-acute disposition requires matching patient acuity, therapy tolerance, and medical needs to facility criteria. SNFs are for skilled care with lower therapy tolerance. IRFs are for intensive rehab (requiring tolerance of at least 3 hours/day). LTACHs are for prolonged acute needs like mechanical ventilator weaning. Hospice is for terminal comfort care.

Step-by-Step Solution

1
Evaluate each patient's ongoing medical and functional needs.
Identified specific requirements such as ventilator weaning, therapy tolerance, and goals of care.
Disposition planning relies on matching the patient's exact clinical status and goals with facility capabilities.
2
Apply standard admission criteria for post-acute care facilities to each scenario.
Matched each patient vignette to the corresponding facility criteria.
Each post-acute care setting has strict clinical and regulatory criteria (e.g., 3-hour therapy rule for IRFs) that must be met.

Key Concept

Disposition and Care Setting Transitions
Question 606Question →

Match each patient's clinical presentation with the most appropriate next diagnostic imaging study based on current guidelines.

Click a left item, then click its matching right item

Items

A 72-year-old man with a history of atrial fibrillation presents with sudden-onset, diffuse abdominal pain out of proportion to his physical examination findings and an elevated serum lactate.
A 29-year-old woman at 24 weeks gestation presents with acute right lower quadrant pain, nausea, and leukocytosis; graded compression ultrasonography visualizes the right ovary but fails to visualize the appendix.
A 65-year-old woman presents with 3 days of progressive left lower quadrant abdominal pain, fever, and a palpable, tender mass in the left lower abdomen; she is hemodynamically stable.
A 38-year-old man with a history of Roux-en-Y gastric bypass presents with severe, sudden-onset left flank pain radiating to the groin, accompanied by gross hematuria.
A 48-year-old woman presents with severe right upper quadrant pain and fever; initial abdominal ultrasonography demonstrates biliary sludge and pericholecystic fluid, but no definitive gallstones.

Matches

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Answer

1 matches with CTA of the abdomen and pelvis. 2 matches with MRI without gadolinium. 3 matches with CT with intravenous contrast. 4 matches with Noncontrast CT. 5 matches with HIDA scan.
Each pairing follows established clinical diagnostic pathways for acute abdominal pain. Vascular emergencies require angiography (CTA). Inflammatory bowel conditions require IV contrast for tissue enhancement. Renal stones require noncontrast imaging to prevent obscuring the stone. Pregnancy mandates non-ionizing radiation (MRI) when ultrasound fails. Equivocal biliary ultrasound requires functional assessment of cystic duct patency (HIDA).

Step-by-Step Solution

1
Analyze the clinical scenario in each left-side item to form a primary suspected diagnosis.
Identified diagnoses: Mesenteric ischemia, appendicitis in pregnancy, complicated diverticulitis, nephrolithiasis, and equivocal acute cholecystitis.
Accurate test sequencing depends directly on the pre-test probability of specific underlying pathologies.
2
Evaluate patient-specific modifiers that alter standard test sequencing.
Noted pregnancy in scenario 2 (requires radiation avoidance) and an already indeterminate initial ultrasound in scenario 5 (necessitates advanced functional testing).
Standard pathways frequently change based on physiologic states (e.g., pregnancy) or previous non-diagnostic test results.
3
Match the most appropriate specific imaging modality (including contrast protocol) to each scenario.
Matched vascular occlusion to CTA, pregnancy to MRI, localized inflammation/abscess to IV contrast CT, stones to noncontrast CT, and functional ductal obstruction to HIDA.
Different tissue pathologies require distinct radiological techniques for optimal visualization and diagnostic accuracy.

Key Concept

The selection of diagnostic imaging in the acute abdomen relies heavily on the suspected underlying mechanism (vascular vs inflammatory vs obstructive) and specific patient constraints (e.g., pregnancy, prior indeterminate tests).
Question 607Question →

A 58-year-old man with a history of treated cavitary pulmonary tuberculosis is brought to the emergency department by ambulance due to a sudden episode of massive hemoptysis. Paramedics report he expectorated approximately 600 mL of bright red blood into a basin during the 20-minute transport. On arrival, the patient is agitated, actively coughing up blood, and visibly struggling to breathe. Vital signs are temperature 37.0°C (98.6°F), blood pressure 82/48 mm Hg, pulse 134/min, and respirations 34/min. Pulse oximetry is 84% on room air. Pulmonary auscultation reveals gurgling and absent breath sounds over the right lung, while the left lung has clear breath sounds. Which of the following are the most appropriate simultaneous initial steps in the stabilization of this patient? (Select 2 answers)

Select all that apply

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Answer: Positioning the patient in the right lateral decubitus position; Performing rapid sequence endotracheal intubation

Answer

The most appropriate simultaneous initial steps are performing rapid sequence endotracheal intubation and positioning the patient in the right lateral decubitus position.
Massive hemoptysis (defined as >500-600 mL expectorated over 24 hours, or any volume expectorated at a rate posing a life threat) is a critical emergency where asphyxiation from blood flooding the alveoli is the primary mechanism of death, rather than hemorrhagic shock. The most crucial initial stabilization steps focus on protecting the functional gas exchange surface area. Performing rapid sequence endotracheal intubation, ideally with a large-bore tube (e.g., size 8.0 or larger), secures a definitive airway, allows for continuous clearance of blood via suctioning, and facilitates advanced procedures like bronchoscopy. Concurrently, protecting the non-bleeding lung is vital. Clinical findings of right-sided gurgling with clear left-sided breath sounds indicate the right lung is the source of hemorrhage. Positioning the patient in the right lateral decubitus position (bleeding lung dependent) utilizes gravity to keep the blood contained in the right lung, thereby preventing spillage into the healthy left lung and preserving necessary gas exchange.

Step-by-Step Solution

1
Assess the severity of the hemoptysis and the immediate threat to life.
The patient has massive hemoptysis (>600 mL) causing respiratory distress, hypoxemia, and hemodynamic instability. The primary risk of death is asphyxiation.
Recognizing massive hemoptysis shifts the immediate clinical priority from diagnostic workup to aggressive airway protection.
2
Localize the source of the bleeding based on physical examination findings.
Gurgling and absent breath sounds strictly on the right side suggest the right lung as the source of hemorrhage.
Identifying the bleeding lung is necessary to implement correct positional therapy.
3
Determine the necessary simultaneous interventions for airway protection and lung isolation.
The patient requires immediate intubation and placement in the right lateral decubitus position.
Intubation secures the airway for oxygenation and continuous suctioning. The right lateral decubitus position uses gravity to keep blood confined to the diseased lung, protecting the healthy left lung from aspiration.

Key Concept

In massive hemoptysis, the primary cause of death is asphyxiation, not exsanguination. Initial stabilization requires immediate airway securement via large-bore endotracheal intubation and positioning the patient with the bleeding lung in the dependent (downward) position to protect the unaffected lung.
Question 608Question →

A 4242-year-old woman comes to the clinic for a follow-up visit. Two weeks ago, she was evaluated for fatigue and was found to have a hemoglobin concentration of 9.8 g/dL9.8 \text{ g/dL}, a mean corpuscular volume of 74 fL74 \text{ fL}, and a serum ferritin level of 8 ng/mL8 \text{ ng/mL}. At that time, she was diagnosed with iron deficiency anemia secondary to heavy menstrual bleeding and was instructed to start oral ferrous sulfate. Today, the patient reports that she has been taking the medication consistently. She still feels somewhat tired but denies shortness of breath, chest pain, or lightheadedness. Her vital signs are within normal limits. Laboratory results today show a hemoglobin concentration of 10.1 g/dL10.1 \text{ g/dL} and a reticulocyte count of 5.2%5.2\% (normal: 0.5%−1.5%0.5\%-1.5\%). Which of the following is the most appropriate next step in management?

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Answer: Continue current therapy and schedule a follow-up in 4 weeks

Answer

Continue current therapy and schedule a follow-up in 4 weeks
Oral iron therapy induces a peak reticulocyte response within 1 to 2 weeks of initiation. However, hemoglobin levels rise much more slowly, typically increasing by 11 to 2 g/dL2 \text{ g/dL} every 3 to 4 weeks, with full normalization taking 6 to 8 weeks. This patient exhibits a brisk reticulocytosis, confirming adequate medication adherence, intestinal absorption, and bone marrow responsiveness. Because her response aligns perfectly with the expected physiological timeline, the best next step is to continue the current regimen and reevaluate her hemoglobin levels in 4 weeks.

Step-by-Step Solution

1
Identify the patient's diagnosis and treatment timeline.
The patient has iron deficiency anemia and has been on oral ferrous sulfate for 2 weeks.
Establishing the duration of therapy is essential for interpreting follow-up laboratory parameters.
2
Interpret the current laboratory findings.
Hemoglobin is minimally increased from baseline (9.89.8 to 10.1 g/dL10.1 \text{ g/dL}), but the reticulocyte count is significantly elevated at 5.2%5.2\%.
This combination of findings differentiates a failing treatment regimen from an effective one that simply requires more time.
3
Determine the expected physiologic timeline for hematologic recovery.
Reticulocytosis peaks at 1 to 2 weeks, while hemoglobin typically rises by 11 to 2 g/dL2 \text{ g/dL} every 3 to 4 weeks.
Applying this timeline confirms that the patient's current laboratory profile represents a successful and expected response to therapy.
4
Formulate the management plan.
Continue the oral iron supplementation and reevaluate the hemoglobin level in 4 weeks.
Intervening prematurely due to isolated lab expectations disrupts standard-of-care management.

Key Concept

Physiological timeline of hematologic recovery in iron deficiency anemia treated with oral iron supplementation.
Question 609Question →

A 46-year-old man comes to the clinic for a routine health maintenance examination. He feels well and has no concerns. His medical history is unremarkable, and he takes no medications. He has no family history of colorectal, prostate, or lung cancer. He does not smoke, drink alcohol, or use illicit drugs. Vital signs are within normal limits. Physical examination is unremarkable. He has not had any cancer screening tests in the past. Which of the following is the most appropriate next step in preventive care for this patient?

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Answer: Recommend screening colonoscopy

Answer

Recommend screening colonoscopy
The correct action is to recommend screening for colorectal cancer. According to current United States Preventive Services Task Force (USPSTF) guidelines, average-risk adults should begin screening for colorectal cancer at age 45. Options for screening include colonoscopy every 10 years, annual fecal immunochemical testing, or other approved modalities. Because this patient is 46 years old and has no history of screening, it is indicated now.

Step-by-Step Solution

1
Identify the patient's demographic and risk profile.
The patient is a 46-year-old man with average risk for malignancies (no family history, no smoking history).
Risk factors and age determine the appropriate preventive screening guidelines.
2
Apply the USPSTF guidelines for an average-risk 46-year-old.
Colorectal cancer screening is indicated starting at age 45.
Guidelines for colorectal cancer screening were updated to lower the initiation age from 50 to 45 for average-risk adults.

Key Concept

Initiation of colorectal cancer screening in average-risk adults
Question 610Question →

A father brings his 3-year-old son to the outpatient pediatric clinic because the child has been refusing to move his left arm for the past hour. The father explains that they were walking in the park when the boy stumbled; to prevent him from falling to the ground, the father quickly pulled the child up by the left hand. Immediately afterward, the child began crying and holding his arm against his side. On physical examination, the boy is alert but appears anxious. He is cradling his left arm close to his body with the elbow slightly flexed and the forearm pronated. There is no visible swelling, ecchymosis, deformity, or point tenderness over the clavicle, shoulder, elbow, or wrist. The child cries and resists only when the clinician attempts to supinate the left forearm. Which of the following is the most appropriate next step in management?

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Answer: Closed reduction via hyperpronation of the left forearm

Answer

Closed reduction via hyperpronation of the left forearm
The correct answer is closed reduction via hyperpronation of the left forearm. The child's presentation—sudden arm pain after an axial pull on the extended arm, resulting in a flexed and pronated posture without swelling or point tenderness—is the classic description of radial head subluxation (nursemaid's elbow). This condition occurs when the annular ligament slips over the head of the radius. Because it is a clinical diagnosis, the most appropriate immediate step in management is procedural reduction. Hyperpronation or the supination-flexion maneuver easily and quickly reduces the ligament, often resulting in immediate relief of pain and return of normal arm function.

Step-by-Step Solution

1
Identify the clinical presentation
The patient is a 3-year-old presenting with acute arm pain after axial traction, holding the arm in pronation and slight flexion with no focal swelling.
This is the classic history and physical examination finding for radial head subluxation (nursemaid's elbow).
2
Determine the necessity of diagnostic workup
No imaging or laboratory tests are needed.
The diagnosis is purely clinical, and X-rays are usually normal as the annular ligament is radiolucent. Imaging is only needed if there is focal tenderness, swelling, or if reduction fails.
3
Select the appropriate procedural intervention
Perform closed reduction via hyperpronation.
Hyperpronation (or the supination-flexion maneuver) is the standard, highly successful procedural intervention to reduce the slipped annular ligament back into its normal anatomical position.

Key Concept

Radial head subluxation (nursemaid's elbow) is a clinical diagnosis managed immediately with a procedural intervention (hyperpronation or supination-flexion) without the need for prior imaging.
Question 611Question →

A 55-year-old man is in the intensive care unit being managed for recurrent seizures secondary to viral encephalitis. His seizures have been well-controlled for the past week on a continuous intravenous infusion of valproic acid. On hospital day 8, he developed a new fever, increased respiratory secretions, and a right lower lobe consolidation on chest radiograph. Sputum and blood cultures were obtained, and he was started empirically on intravenous meropenem. On hospital day 10, the patient experiences a 3-minute generalized tonic-clonic seizure.

Relevant laboratory results are shown below:

ParameterHospital Day 7Hospital Day 9Hospital Day 10 (Today)Reference Range
Leukocyte count8,500/μL8,500/\mu L15,200/μL15,200/\mu L14,800/μL14,800/\mu L4,000−11,000/μL4,000-11,000/\mu L
Serum valproic acid85 μg/mL85\ \mu g/mL35 μg/mL35\ \mu g/mL12 μg/mL12\ \mu g/mL50−100 μg/mL50-100\ \mu g/mL
Serum creatinine0.9 mg/dL0.9\ mg/dL0.9 mg/dL0.9\ mg/dL1.0 mg/dL1.0\ mg/dL0.6−1.2 mg/dL0.6-1.2\ mg/dL

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

Show answer & explanation

Answer: Discontinue meropenem and initiate an alternative antipseudomonal antibiotic

Answer

The correct action is to discontinue meropenem and initiate an alternative antipseudomonal antibiotic.
The correct management is to discontinue the interacting antibiotic. Meropenem, like all carbapenems, is well known to cause a precipitous and profound decrease in serum valproic acid concentrations, frequently leading to subtherapeutic levels and breakthrough seizures within 24 to 48 hours of initiation. Because this interaction is rapid and difficult to overcome with dose adjustments, the standard of care is to substitute the carbapenem with a different class of antibiotics, such as a cephalosporin or a penicillin derivative.

Step-by-Step Solution

1
Analyze the clinical timeline and presentation.
A patient with previously controlled seizures develops breakthrough generalized tonic-clonic seizures two days after starting a new medication (meropenem).
Establishing the timeline is critical for identifying potential drug-drug interactions or adverse events.
2
Evaluate the longitudinal laboratory data.
The serum valproic acid level dropped precipitously from a therapeutic level of 85 μg/mL85\ \mu g/mL to a subtherapeutic level of 12 μg/mL12\ \mu g/mL concurrently with the administration of meropenem.
Serial labs confirm that the loss of seizure control is directly due to subtherapeutic antiepileptic drug levels rather than structural neurological worsening.
3
Identify the underlying pharmacokinetic mechanism.
Carbapenem antibiotics (e.g., meropenem, imipenem, ertapenem) rapidly and profoundly decrease serum valproic acid concentrations.
This occurs via inhibition of intestinal absorption, increased erythrocyte distribution, and enhanced hepatic clearance (glucuronidation).
4
Determine the appropriate treatment adaptation.
The offending agent (meropenem) must be discontinued and substituted with an alternative antibiotic (e.g., cefepime or piperacillin-tazobactam) to allow valproic acid levels to recover.
Simply increasing the valproic acid dose cannot reliably overcome this severe interaction.

Key Concept

Carbapenem antibiotics cause a rapid and clinically significant decrease in serum valproic acid levels, often leading to breakthrough seizures; the appropriate management is to discontinue the carbapenem.
Question 612Question →

An 81-year-old woman is evaluated on hospital day 5 to determine the appropriate post-acute care setting. She was initially admitted for altered mental status and hypotension secondary to a severe Escherichia coli urinary tract infection. She received intravenous fluids and targeted antibiotic therapy. Currently, her blood pressure is 128/78 mmHg, pulse is 82/min, and respirations are 16/min. She has been afebrile for 48 hours. Her leukocyte count is 8,200/mm³ and serum creatinine has improved from 2.6 mg/dL on admission to 1.0 mg/dL. Her baseline functional status before admission was independent in all activities of daily living. She resides in a single-story house with her 83-year-old husband, who uses a walker due to advanced osteoarthritis. Currently, the patient is easily fatigued, oriented only to person and place, and requires the assistance of two staff members to transfer from the bed to a chair. A physical therapy evaluation notes that she can actively participate in structured exercises for approximately 45 minutes per day before becoming exhausted. Which of the following is the most appropriate disposition for this patient?

Show answer & explanation

Answer: Discharge to a skilled nursing facility

Answer

Discharge to a skilled nursing facility
The correct answer accurately synthesizes the patient's current needs: she is medically stable (resolving her acute infection and organ dysfunction) but has acquired a severe, temporary functional deficit. She requires 2-person assistance to transfer, meaning she cannot safely return home where her only caregiver is a frail spouse. Furthermore, because she can only tolerate 45 minutes of physical therapy per day due to fatigue and resolving delirium, she does not qualify for an acute inpatient rehabilitation facility, which mandates active participation in at least 3 hours of therapy per day. Therefore, a skilled nursing facility (SNF) is the optimal disposition, as it provides the necessary 24-hour nursing care and a slower-paced subacute rehabilitation program.

Step-by-Step Solution

1
Evaluate the patient's current medical stability.
The patient is hemodynamically stable, afebrile, and her laboratory values (WBC, creatinine) have normalized.
To determine if continued acute inpatient care is medically justified.
2
Assess the patient's functional status and rehabilitation capacity.
The patient requires 2-person assistance for transfers and can only participate in 45 minutes of physical therapy per day.
To identify the appropriate level of therapy intensity and nursing care required.
3
Analyze the patient's home support system.
The patient lives with a frail 83-year-old husband who uses a walker, indicating profound limitations in home caregiver support.
To determine if a discharge to home with outpatient or visiting nurse services is safe and feasible.
4
Match the patient's clinical and social profile to the appropriate post-acute care setting.
A skilled nursing facility (SNF) is selected.
An SNF provides the required 24-hour nursing care and lower-intensity subacute therapy appropriate for her fatigue, avoiding the unsafe home environment and the overly rigorous demands of an acute rehabilitation hospital.

Key Concept

Appropriate patient disposition relies on synthesizing medical stability, objective physical therapy tolerance (e.g., ability to perform 3 hours of daily therapy), and available home support to ensure safe and effective care transitions.
Question 613Question →

A 68-year-old man is admitted to the general medical ward with acute-onset fever, tachypnea, and a right lower lobe infiltrate on chest radiograph. He is diagnosed with community-acquired pneumonia. Arrange the following steps in the correct chronological sequence for his initial management, ongoing monitoring, and therapeutic de-escalation.

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Answer

The correct sequence begins with obtaining appropriate diagnostic cultures, followed immediately by initiating empiric intravenous antibiotics. The patient is then monitored for 48 to 72 hours to evaluate the treatment response. Once clinical stability is achieved, therapy is de-escalated to oral antibiotics, culminating in discharge planning and arrangement of outpatient follow-up.
The correct sequence adheres to established protocols for inpatient pneumonia management: diagnostics (cultures) first, prompt therapeutic intervention (IV antibiotics), careful monitoring of the intervention's efficacy (48-72 hours), therapeutic de-escalation based on objective stability parameters (IV to PO switch), and finally, safe disposition (discharge and follow-up).

Step-by-Step Solution

1
Identify the need for immediate diagnostic testing before therapy.
Blood cultures and baseline labs are placed first in the sequence.
Administering antibiotics prior to obtaining cultures significantly decreases the likelihood of identifying the causative pathogen.
2
Initiate acute pharmacologic intervention.
Empiric intravenous antibiotics are placed second.
Delaying antibiotic administration in community-acquired pneumonia increases morbidity and mortality.
3
Establish the monitoring and treatment evaluation phase.
Monitoring clinical parameters for 48 to 72 hours is placed third.
Guideline-concordant care requires a minimum observation period to ensure the empiric antibiotic regimen is effective and the patient is stabilizing.
4
Implement multi-step therapeutic de-escalation.
Transitioning to oral antibiotics is placed fourth.
Patients should only be switched to oral therapy after meeting objective criteria for clinical stability (e.g., afebrile, resolving tachycardia, able to take oral fluids).
5
Finalize care setting transition.
Discharge planning and outpatient follow-up are placed fifth.
Discharge is the final step in the inpatient treatment pathway once the patient has been successfully transitioned to oral therapy.

Key Concept

The chronological sequence for managing inpatient community-acquired pneumonia involves diagnostics prior to therapy, prompt empiric antibiotics, continuous evaluation of treatment response, and criteria-driven therapeutic de-escalation to oral therapy prior to discharge.
Question 614Question →

A 5858-year-old woman is evaluated in the intensive care unit for altered mental status, severe agitation, and fever. She has a history of major depressive disorder, generalized anxiety disorder, and chronic back pain. Her home medications include fluoxetine, tramadol, and cyclobenzaprine. Two days ago, she was admitted for severe community-acquired pneumonia and was started on broad-spectrum antimicrobial therapy, including intravenous linezolid. Today, she is diaphoretic and confused. Temperature is 39.4∘C39.4^\circ\text{C} (102.9∘F102.9^\circ\text{F}), blood pressure is 165/100165/100 mmHg, heart rate is 128128/min, and respiratory rate is 2424/min. Physical examination reveals mydriasis, excessive diaphoresis, hyperactive bowel sounds, and inducible myoclonus in the bilateral lower extremities. Which of the following are the most appropriate immediate pharmacologic interventions? (Select all that apply)

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Answer: Discontinue fluoxetine, tramadol, cyclobenzaprine, and linezolid; Administer intravenous lorazepam; Administer cyproheptadine via nasogastric tube

Answer

The correct interventions are to discontinue all serotonergic medications (fluoxetine, tramadol, cyclobenzaprine, and linezolid), administer intravenous lorazepam, and administer cyproheptadine via nasogastric tube.
The correct pharmacologic interventions address the severe serotonin syndrome caused by the interaction between linezolid (an MAOI) and the patient's home serotonergic medications (fluoxetine, tramadol, cyclobenzaprine). The first step is to discontinue all offending agents. Intravenous lorazepam is administered to control agitation and muscle hyperactivity, which subsequently helps reduce hyperthermia. Because the patient has severe toxicity (temperature > 39°C, marked autonomic instability), the specific serotonin antagonist cyproheptadine is indicated and can be administered via a nasogastric tube.

Step-by-Step Solution

1
Identify the underlying toxidrome based on clinical presentation.
The patient presents with autonomic instability, altered mental status, and neuromuscular hyperactivity (myoclonus, hyperreflexia, hyperactive bowel sounds).
These signs form the classic clinical triad of serotonin syndrome, distinguishing it from other hyperthermic syndromes like neuroleptic malignant syndrome.
2
Determine the precipitating pharmacologic cause.
The addition of intravenous linezolid to a home regimen of fluoxetine, tramadol, and cyclobenzaprine.
Linezolid is a reversible, nonselective monoamine oxidase inhibitor (MAOI) that strongly interacts with other serotonergic agents, frequently precipitating severe serotonin syndrome.
3
Select the appropriate immediate pharmacologic management steps.
Discontinue all offending agents, provide supportive care with benzodiazepines, and administer a specific serotonin antagonist.
Immediate withdrawal of serotonergic drugs is essential. Lorazepam controls agitation and hyperthermia. Given the severity (temperature > 39°C), cyproheptadine is indicated as a targeted antidote.

Key Concept

Management of severe serotonin syndrome requires the immediate discontinuation of all serotonergic agents, supportive care with benzodiazepines (e.g., lorazepam) to control agitation and muscle hyperactivity, and the administration of cyproheptadine as a specific serotonin antagonist. Linezolid is a common iatrogenic trigger due to its MAOI properties.
Question 615Question →

A 56-year-old man is evaluated in the emergency department for right upper quadrant abdominal pain, jaundice, and black, tarry stools that started 24 hours ago. Five days ago, he underwent an ultrasound-guided percutaneous liver biopsy to evaluate undiagnosed cirrhosis. His temperature is 37.1°C (98.8°F), blood pressure is 102/64 mm Hg, pulse is 112/min, and respirations are 16/min. Physical examination shows scleral icterus and right upper quadrant tenderness without guarding or rebound. Laboratory studies reveal a hemoglobin level of 8.2 g/dL (baseline 13.5 g/dL) and a total bilirubin of 4.8 mg/dL. Following the administration of intravenous fluids and packed red blood cells, the patient undergoes an esophagogastroduodenoscopy. The esophageal and gastric mucosa are normal, and no varices are identified. However, fresh blood is observed actively extruding from the ampulla of Vater. Which of the following is the most appropriate next step in management?

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Answer: Angiography with selective transarterial embolization

Answer

Angiography with selective transarterial embolization
This patient presents with classic signs of hemobilia (Quincke's triad: right upper quadrant pain, jaundice, and upper gastrointestinal bleeding) five days after a percutaneous liver biopsy. The esophagogastroduodenoscopy confirms the diagnosis by visualizing fresh blood exiting the ampulla of Vater. Hemobilia in this context is most commonly due to an iatrogenic arteriobiliary fistula formed during the biopsy. Because the patient has significant bleeding (drop in hemoglobin, tachycardia), definitive intervention is required. Angiography with selective transarterial embolization is the gold standard and first-line therapy. It allows for both precise localization of the bleeding vessel and immediate therapeutic occlusion, avoiding the high morbidity of open surgery.

Step-by-Step Solution

1
Identify the clinical triad and endoscopic findings.
The patient presents with Quincke's triad (right upper quadrant pain, jaundice, and gastrointestinal bleeding) and endoscopic evidence of blood from the ampulla of Vater following a recent liver biopsy.
These findings definitively establish the diagnosis of hemobilia, typically caused by an iatrogenic arteriobiliary fistula.
2
Determine the optimal procedural intervention.
The patient requires immediate control of the arterial bleeding source.
Transcatheter arterial embolization is the preferred first-line treatment, offering high success rates with lower morbidity compared to open surgery.

Key Concept

Hemobilia often presents with Quincke's triad (right upper quadrant pain, jaundice, gastrointestinal bleeding) after hepatic instrumentation; the first-line definitive procedural management is angiography with selective transarterial embolization.
Estimated Time:1m 30s
Question 616Question →

A 64-year-old man presents with sudden, intractable, generalized abdominal pain that began 2 hours ago. His medical history is significant for coronary artery disease, chronic obstructive pulmonary disease, and daily naproxen use for severe osteoarthritis. Vital signs show a temperature of 38.6°C (101.5°F), blood pressure of 86/52 mmHg, heart rate of 124/min, and respiratory rate of 28/min. Physical examination reveals a rigid, board-like abdomen with severe diffuse tenderness, rebound, and involuntary guarding. An upright chest radiograph demonstrates free air under the right hemidiaphragm. The surgical service is consulted, and an emergent exploratory laparotomy is planned.

Which of the following interventions are essential components of this patient's immediate preoperative management? (Select all that apply)

Select all that apply

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Answer: Intravenous administration of broad-spectrum antibiotics; Rapid intravenous infusion of isotonic crystalloids; Placement of a nasogastric tube for gastrointestinal decompression

Answer

The essential interventions include intravenous administration of broad-spectrum antibiotics, rapid intravenous infusion of isotonic crystalloids, and placement of a nasogastric tube for gastrointestinal decompression.
This patient presents with a classic perforated viscus and subsequent septic shock, necessitating emergent exploratory laparotomy. The immediate procedural and medical interventions must focus on rapid stabilization prior to surgical incision. This includes restoring intravascular volume with isotonic crystalloids, initiating broad-spectrum antibiotics to treat the developing peritonitis, and placing a nasogastric tube to decompress the stomach, which minimizes further peritoneal soilage and protects the airway from aspiration during intubation.

Step-by-Step Solution

1
Identify the primary diagnosis and patient stability.
The patient has a perforated viscus (likely a peptic ulcer given the naproxen use, rigid abdomen, and pneumoperitoneum) leading to septic shock (hypotension, tachycardia, fever).
Establishing the severity of the presentation dictates the urgency of surgical source control and the required immediate resuscitative efforts.
2
Determine the mandatory preoperative stabilization measures.
The patient requires immediate fluid resuscitation for shock, broad-spectrum antibiotics for intra-abdominal sepsis, and nasogastric decompression.
These interventions stabilize hemodynamics for anesthesia, control the septic source medically, and prevent further peritoneal contamination and aspiration.
3
Identify contraindicated or unnecessary delays.
Advanced imaging (CT scan) and cardiac risk stratification (echocardiogram) are omitted.
The diagnosis is already definitively established. Delaying emergent, life-saving surgery for further diagnostic or prognostic testing significantly increases mortality.

Key Concept

Essential preoperative stabilization for an emergent laparotomy in a patient with a perforated viscus includes aggressive hemodynamic resuscitation, early broad-spectrum antibiotics, and nasogastric decompression, without delaying surgery for advanced imaging or cardiac risk stratification.
Question 617Question →

A 68-year-old man presents to the emergency department complaining of sudden, excruciating pain in his left leg that began 4 hours ago. He has a history of paroxysmal atrial fibrillation and recently stopped taking his prescribed rivaroxaban due to financial constraints. On physical examination, the left lower extremity is notably pale and cool to the touch from the mid-thigh distally. The left femoral pulse is palpable, but the popliteal, dorsalis pedis, and posterior tibial pulses are absent. Handheld continuous-wave Doppler reveals no arterial signals in the left foot, but venous signals remain audible. Neurologic examination of the left lower extremity demonstrates profound loss of sensation extending up to the mid-calf and a new-onset inability to dorsiflex the foot. Intravenous heparin and adequate analgesia are administered immediately. Which of the following is the most appropriate next step in the management of this patient?

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Answer: Emergent open surgical embolectomy

Answer

Emergent open surgical embolectomy is the correct intervention for a patient with Rutherford IIb acute limb ischemia.
The correct answer accurately identifies the need for immediate surgical intervention. The patient presents with Rutherford category IIb acute limb ischemia, characterized by rest pain, sensory loss beyond the toes, mild-to-moderate muscle weakness (inability to dorsiflex), absent arterial Doppler signals, and audible venous signals. Because the limb is immediately threatened and will suffer irreversible damage if not reperfused within a few hours, the definitive treatment is emergent open surgical embolectomy. This rapidly restores blood flow, which is critical given the presence of acute neurologic deficits.

Step-by-Step Solution

1
Analyze the patient's symptoms and physical exam findings.
The patient has acute onset leg pain, pallor, absent pulses, absent arterial Doppler signals, audible venous signals, sensory loss extending to the calf, and motor weakness (inability to dorsiflex).
These findings are classic for acute limb ischemia, likely embolic given the history of untreated atrial fibrillation.
2
Classify the severity of the acute limb ischemia using the Rutherford classification system.
The presence of motor weakness and sensory loss beyond the toes, combined with audible venous signals, classifies this as a Rutherford IIb (immediately threatened) limb.
Classification dictates the timeline and type of procedural intervention required.
3
Determine the appropriate procedural intervention based on the classification.
Rutherford IIb requires emergent surgical revascularization (embolectomy).
Limb viability is measured in hours. Time-consuming diagnostics (CTA) or slow-acting therapies (catheter-directed thrombolysis) must be bypassed in favor of immediate surgical reperfusion.

Key Concept

Patients presenting with Rutherford category IIb acute limb ischemia (immediately threatened, presenting with motor deficits or sensory loss beyond the toes) require emergent open surgical revascularization without delay for advanced imaging.
Question 618Question →

A 48-year-old man comes to the clinic for follow-up of treatment-resistant hypertension. His blood pressure remains 168/98 mmHg despite adherence to maximum doses of amlodipine, lisinopril, and hydrochlorothiazide. Laboratory studies two weeks ago showed a serum potassium of 3.1 mEq/L. Subsequent evaluation revealed a plasma aldosterone concentration (PAC) of 34 ng/dL and a suppressed plasma renin activity (PRA) of 0.4 ng/mL/h. A confirmatory intravenous saline infusion test demonstrated persistent elevation of aldosterone levels, confirming the diagnosis of primary aldosteronism. An abdominal computed tomography (CT) scan shows a 1.4-cm, lipid-rich adenoma in the right adrenal gland and a morphologically normal left adrenal gland. The patient is a good surgical candidate and expresses a strong desire for a definitive surgical cure. Which of the following is the most appropriate next step in management?

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Answer: Adrenal venous sampling

Answer

Adrenal venous sampling is the most appropriate next step to functionally confirm lateralization of aldosterone hypersecretion prior to considering surgery.
In the diagnostic workup of primary aldosteronism, identifying the functional source of aldosterone hypersecretion is critical before surgical intervention. While a CT scan may show a unilateral nodule, nonfunctioning adrenal adenomas (incidentalomas) are increasingly common with advancing age. Therefore, in patients older than 35 years, cross-sectional imaging alone has a high false-positive rate for identifying the active source. Adrenal venous sampling is the most accurate test to differentiate a unilateral aldosterone-producing adenoma from bilateral idiopathic adrenal hyperplasia. It must be performed in this 48-year-old patient to functionally confirm that the right-sided adenoma is actively hypersecreting aldosterone before pursuing a unilateral adrenalectomy. If the patient were strictly under 35 years old with marked aldosteronism and a clear unilateral adenoma, surgery without this step might be considered.

Step-by-Step Solution

1
Identify the confirmed diagnosis and clinical scenario.
The patient has biochemically confirmed primary aldosteronism and is seeking surgical management.
This establishes that the patient has completed the initial screening and confirmation phases of the diagnostic algorithm.
2
Evaluate the imaging findings in the context of the patient's demographics.
The patient is 48 years old with a 1.4-cm right adrenal nodule on CT.
Age is a critical variable; patients >35 years have a high background prevalence of nonfunctioning adrenal incidentalomas.
3
Determine the necessary sequencing step before irreversible surgical intervention.
Adrenal venous sampling must be performed.
Because the nodule could be an incidentaloma with contralateral or bilateral hyperplasia causing the excess aldosterone, functional lateralization is mandatory before adrenalectomy.

Key Concept

In patients older than 35 years with primary aldosteronism who are candidates for surgery, adrenal venous sampling is required to distinguish between unilateral aldosterone-producing adenomas and bilateral hyperplasia, even if cross-sectional imaging shows a unilateral nodule.
Question 619Question →

During an interdisciplinary rounds discussion on the psychiatric ward, the care team plans the discharge of a 35-year-old female who was recently stabilized from an acute manic episode. The patient was successfully transitioned to maintenance lithium carbonate therapy over the past ten days. Her current serum lithium trough level is within the therapeutic window. To appropriately monitor for the most common long-term adverse effects of this pharmacotherapy, which of the following laboratory parameters should be periodically evaluated in the outpatient setting? (Select all that apply)

Select all that apply

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Answer: Thyroid-stimulating hormone; Serum creatinine

Answer

The correct parameters to monitor routinely are thyroid-stimulating hormone and serum creatinine.
Lithium is a foundational mood stabilizer that carries specific long-term toxicity risks. It is primarily excreted by the kidneys and can induce chronic tubulointerstitial nephropathy over time, which can ultimately lead to chronic kidney disease. Therefore, renal function must be tracked via periodic serum creatinine measurements. Additionally, lithium frequently interferes with thyroid hormone synthesis and release, leading to hypothyroidism, which mandates regular monitoring of thyroid-stimulating hormone (TSH). Calcium levels are also often checked due to the risk of hyperparathyroidism, though renal and thyroid panels remain the most critically emphasized.

Step-by-Step Solution

1
Identify the prescribed medication and its clearance mechanism.
The medication is lithium, which is not metabolized by the liver but is entirely excreted by the kidneys.
Understanding the pharmacokinetic profile helps predict organ-specific toxicities.
2
Determine the primary organ systems affected by long-term lithium toxicity.
Long-term lithium use is predominantly associated with renal toxicity (nephrogenic diabetes insipidus, tubulointerstitial nephropathy) and thyroid dysfunction (hypothyroidism, goiter).
These established toxicities dictate the required laboratory surveillance protocols.
3
Select the appropriate screening tests corresponding to the affected organ systems.
Serum creatinine (renal function) and thyroid-stimulating hormone (thyroid function) should be periodically evaluated.
Guideline-concordant care mandates tracking these specific parameters to detect silent adverse effects early.

Key Concept

Long-term outpatient monitoring for lithium therapy requires periodic assessment of renal function (serum creatinine, BUN) and thyroid function (TSH) due to the risks of tubulointerstitial nephropathy and hypothyroidism.
Question 620Question →

A 71-year-old man comes to the clinic reporting a 2-month history of worsening mid-to-lower back pain. The pain is constant, does not improve with rest, and occasionally awakens him at night. Over the same period, he has experienced progressive fatigue, constipation, and increased urinary frequency. His past medical history is notable only for mild osteoarthritis, for which he takes acetaminophen as needed. He does not use tobacco, alcohol, or illicit drugs. Vital signs are within normal limits. Physical examination reveals tenderness to palpation over the lumbar spine but no focal neurological deficits.

Laboratory results are as follows:

Hemoglobin: 9.2 g/dL9.2 \text{ g/dL}
Leukocyte count: 6,500/μL6,500/\mu\text{L}
Platelet count: 140,000/μL140,000/\mu\text{L}
Calcium: 11.8 mg/dL11.8 \text{ mg/dL}
Creatinine: 2.1 mg/dL2.1 \text{ mg/dL}
Alkaline phosphatase: 95 U/L95 \text{ U/L}

Which of the following diagnostic tests should be ordered concurrently as the most appropriate next steps in this patient's initial workup? (Select all that apply)

Select all that apply

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Answer: Serum protein electrophoresis with immunofixation; Serum free light chain assay

Answer

The most appropriate initial diagnostic steps are serum protein electrophoresis with immunofixation and a serum free light chain assay.
This patient presents with the classic 'CRAB' manifestations of multiple myeloma: hyperCalcemia (constipation, polyuria), Renal insufficiency (elevated creatinine), Anemia (fatigue, low hemoglobin), and Bone pain (lumbar tenderness). The correct sequencing of diagnostic tests begins with non-invasive identification of a monoclonal paraprotein. Current guidelines recommend ordering serum protein electrophoresis with immunofixation, urine protein electrophoresis, and a serum free light chain assay concurrently to maximize initial screening sensitivity.

Step-by-Step Solution

1
Analyze the patient's clinical and laboratory presentation.
The patient exhibits hypercalcemia, renal insufficiency, anemia, and bone pain (CRAB symptoms).
Identifying this specific constellation of findings is necessary to formulate a focused differential diagnosis.
2
Identify the most likely underlying condition.
The clinical picture strongly suggests multiple myeloma.
Multiple myeloma classically presents in older adults with the CRAB criteria, along with a normal alkaline phosphatase level indicating purely osteolytic rather than osteoblastic bone involvement.
3
Determine the optimal sequencing for the initial diagnostic workup.
Order non-invasive serologic screening tests, specifically serum protein electrophoresis (SPEP) with immunofixation and a serum free light chain assay.
Guideline-concordant test sequencing requires establishing the presence of a monoclonal protein non-invasively before proceeding to invasive confirmatory procedures like a bone marrow biopsy.

Key Concept

The initial diagnostic workup of suspected multiple myeloma requires concurrent non-invasive screening with serum/urine protein electrophoresis and serum free light chain assays prior to invasive confirmatory testing.
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