All practice questions

A 32-year-old woman is brought to the emergency department by her husband due to agitation, confusion, and shivering. She has a history of major depressive disorder, for which she is maintained on citalopram. Three days ago, she visited an urgent care clinic for a severe respiratory infection and was prescribed linezolid. On physical examination, her temperature is $39.4^\circ\text{C}$ ($102.9^\circ\text{F}$), pulse is $122/\text{min}$, and blood pressure is $165/98 \text{ mm Hg}$. She is diaphoretic and exhibits ocular clonus and bilateral lower extremity hyperreflexia. Intravenous fluids and benzodiazepines are administered, but her symptoms persist. The physician decides to administer cyproheptadine as a targeted antidote. Which of the following best describes the expected pharmacodynamic effect of this antidote on the dose-response curve of the involved endogenous neurotransmitter?

Match each patient's clinical presentation involving a discordant or potentially artifactual initial laboratory result with the most appropriate next step in laboratory evaluation.

An evaluation is requested in the emergency department for a $48$-year-old female patient complaining of acute-onset abdominal discomfort. The pain localized to the right upper quadrant approximately $12$ hours prior, shortly after she consumed a heavy meal. Associated symptoms include intermittent nausea and a feeling of warmth. Vital signs demonstrate a temperature of $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), a heart rate of $96\text{/min}$, a respiratory rate of $18\text{/min}$, and a blood pressure of $132/84\text{ mmHg}$. Upon physical assessment of the abdomen, the examiner places their hand firmly below the right costal margin and instructs the patient to breathe in deeply. Midway through inspiration, she suddenly gasps and stops breathing in due to a sharp spike in pain. Serum analysis shows a white blood cell count of $12,500\text{/mm}^3$ with an unremarkable basic metabolic panel and normal lipase. Based on this characteristic examination finding, which of the following represents the optimal next diagnostic intervention?

A detailed understanding of cytokine networks and immune cell interactions is essential for recognizing the pathogenesis of various inflammatory, autoimmune, and infectious conditions, as well as for utilizing targeted biologic therapies. Match each clinical presentation or pathologic process with the primary cytokine or immunologic mechanism that directly drives its development.

An ambulatory care physician is seeing a 28-year-old man who complains of severe restlessness, uncontrollable shivering, and a "racing heart" that began 24 hours ago. His past psychiatric history is notable for generalized anxiety disorder and major depressive disorder, which have been well controlled on paroxetine for the past three years. He has no other chronic medical conditions. Vital signs show a temperature of 38.4°C (101.1°F), blood pressure of 158/92 mmHg, pulse of 115/min, and respirations of 18/min. On physical examination, the patient is visibly diaphoretic and tremulous. Neurologic examination reveals prominent hyperreflexia and bilateral inducible ankle clonus. Point-of-care laboratory testing reveals a mild leukocytosis of 11,500/mm³. The physician suspects a specific toxidrome and begins a targeted medical history evaluation. Which of the following historical elements is most likely responsible for this patient's current condition?

Match each of the following clinical scenarios with the most accurate corresponding pharmacokinetic alteration expected in that patient.

Obtaining a thorough dietary and non-prescription supplement history is a critical component of medical evaluation, as patients often omit these exposures unless specifically asked. Match each unique patient history profile to the clinical presentation most commonly associated with that hidden exposure.

A 26-year-old woman is evaluated in the hematology clinic prior to a scheduled elective cholecystectomy due to an incidentally discovered prolonged activated partial thromboplastin time (aPTT) on routine preoperative laboratory screening. She reports a history of heavy menstrual bleeding necessitating the use of oral contraceptives. She also states she experienced prolonged bleeding following a wisdom tooth extraction 5 years ago. She has no history of deep venous thrombosis, joint swelling, or spontaneous bruising. Her family history is unremarkable for known bleeding disorders. Physical examination is within normal limits with no petechiae or ecchymoses.

Laboratory results:
Prothrombin time (PT): 11 seconds (Normal: 11-15 sec)
Activated partial thromboplastin time (aPTT): 48 seconds (Normal: 25-35 sec)
Platelet count: $280,000/\mu L$

A $1:1$ mixing study with normal pooled plasma is performed. The patient's aPTT corrects to 29 seconds immediately, and remains 30 seconds after a 2-hour incubation.

Which of the following is the most appropriate next step in laboratory evaluation?

During comprehensive neurological physical examinations, observing a patient's gait provides critical diagnostic clues regarding the precise location of neurological lesions. Match each detailed physical examination description of a gait abnormality with its most likely underlying neuroanatomical localization or pathophysiological mechanism.

Match the following arterial blood gas (ABG) profiles on room air to their most appropriate primary acid-base disorder.

A 52-year-old woman presents to the clinic complaining of severe fatigue, generalized joint aches, and a new rash on her lower extremities that appeared $3$ days ago. She has a history of intravenous drug use in her twenties but states she has been abstinent for over two decades. On physical examination, her temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), blood pressure is $145/90 \text{ mm Hg}$, and pulse is $82/\text{min}$. Examination of the legs reveals non-blanching, erythematous macules and papules that coalesce into plaques. Laboratory studies reveal the following:

Urinalysis shows $2+$ protein, $15-20$ red blood cells/hpf, and occasional red blood cell casts. Which of the following best describes the fundamental immunopathologic mechanism responsible for this patient's cutaneous and renal findings?

A 34-year-old woman presents to the clinic with a 2-month history of unintentional weight loss, frequent palpitations, and heat intolerance. On physical examination, her heart rate is $112/\text{min}$, and she has a fine resting tremor. Neck examination reveals a diffusely enlarged, non-tender thyroid gland. Laboratory evaluation demonstrates a thyroid-stimulating hormone (TSH) level of $0.01 \text{ }\mu\text{U/mL}$ (reference: $0.4-4.0 \text{ }\mu\text{U/mL}$) and a free thyroxine ($T_4$) level of $3.2 \text{ ng/dL}$ (reference: $0.9-1.7 \text{ ng/dL}$). She is diagnosed with Graves disease and prescribed methimazole. To understand the cellular mechanism of this patient's disease and her new medication, the physician reviews the physiological sequence of thyroid hormone synthesis. Arrange the following steps of normal thyroid hormone synthesis and release in the correct chronological order, beginning with the initial uptake of the raw material from the bloodstream.

An independent 62-year-old gentleman is brought to the emergency department by his daughter due to an abrupt onset of a severe room-spinning sensation that began 6 hours ago. He reports intense nausea and an inability to walk without assistance. His past medical history is significant for essential hypertension and hyperlipidemia. Vital signs show a blood pressure of 165/95 mmHg, heart rate of 88/min, and respiratory rate of 16/min. The patient is alert and fully oriented. Cardiopulmonary examination is unremarkable. During the neurological evaluation, the physician performs a provocative positioning test by rapidly moving the patient from a sitting to a supine position with his head turned 45 degrees. This maneuver immediately elicits purely vertical, down-beating nystagmus that persists continuously for over 2 minutes without diminishing in intensity. The patient's hearing is intact bilaterally to finger rub. Based on these physical examination findings, which of the following is the most appropriate next step in the management of this patient?

A 66-year-old woman is evaluated in the emergency department for a 4-day history of severe, non-bloody diarrhea. She reports having up to 10 watery bowel movements daily, accompanied by diffuse abdominal cramping and a low-grade fever. She has a history of metastatic melanoma and began therapy with pembrolizumab 6 weeks ago. Her temperature is 37.8°C (100.0°F), blood pressure is 110/70 mm Hg, and pulse is 108/min. Physical examination reveals a diffusely tender abdomen with hyperactive bowel sounds, but no rebound tenderness or guarding. Laboratory studies show a serum potassium of 3.1 mEq/L and an elevated C-reactive protein. Stool PCR for *Clostridioides difficile* and routine enteric stool cultures are negative. A flexible sigmoidoscopy reveals diffuse mucosal erythema, loss of vascular pattern, and patchy ulcerations. Biopsy demonstrates a dense lymphoplasmacytic infiltrate expanding the lamina propria. In addition to intravenous fluid resuscitation, which of the following is the most appropriate targeted intervention and its corresponding immunopathologic rationale?

During morning rounds on the medical ward, a physician evaluates a 62-year-old man who was admitted overnight with a 3-day history of profound generalized muscle weakness, severe myalgias, and dark brown urine. The patient has a background of ischemic heart disease, hypertension, and mixed dyslipidemia, which are managed chronically with daily aspirin, metoprolol, ramipril, and simvastatin. Upon reviewing the electronic health record, the physician notes that 10 days prior, the patient visited an out-of-state urgent care clinic for a high fever and productive cough. He was diagnosed with community-acquired pneumonia and completed a 7-day course of an oral antimicrobial agent. Current laboratory studies reveal a serum creatinine of $2.6$ mg/dL (baseline $1.1$ mg/dL) and a creatine kinase level of $14,500$ U/L. Which of the following antimicrobial agents, if identified during a reconciliation of the patient's recent medical history, most likely precipitated his current clinical condition?

A hematology-oncology tumor board is reviewing molecular pathology reports for several adult patients with newly diagnosed leukemias and lymphomas. The board discusses how these specific chromosomal abnormalities dictate both the fundamental pathophysiology and the selection of targeted therapies. Match each identified cytogenetic translocation with its corresponding primary molecular consequence.

A 68-year-old woman is admitted to the hospital with a complicated intra-abdominal infection. She is started on a newly approved intravenous antimicrobial agent. The standard maintenance dose of this medication for patients with normal renal function (defined as a creatinine clearance of $100 \text{ mL/min}$) is $600 \text{ mg}$ administered every 24 hours. Pharmacokinetic data indicate that in healthy individuals, $60\%$ of the drug is eliminated unchanged in the urine, while the remaining $40\%$ undergoes hepatic metabolism. The patient's basic metabolic panel reveals an elevated serum creatinine, and her creatinine clearance is estimated to be $25 \text{ mL/min}$. Assuming linear pharmacokinetics and normal hepatic function, what should be the new daily maintenance dose in $\text{mg}$ to achieve the same steady-state average drug concentration as a patient with normal renal function?

A 26-year-old female marathon runner is brought to the emergency department by her partner due to sudden-onset shortness of breath, headache, and a noticeable bluish discoloration of her lips and fingertips. She has no significant past medical history and takes no daily prescription medications. Three days ago, she sustained a minor hamstring strain during a training run and has been treating it at home. On physical examination, the patient is anxious and tachypneic. Vital signs include a blood pressure of 110/70 mmHg, a heart rate of 112/min, and a respiratory rate of 22/min. Pulse oximetry on room air reads 85%. She is immediately placed on 100% oxygen via a non-rebreather mask, but her pulse oximetry reading remains unchanged at 85% after 15 minutes. An arterial blood gas (ABG) analysis obtained while on supplemental oxygen reveals:

pH: 7.42
PaCO2: 36 mmHg
PaO2: 240 mmHg
Calculated SaO2: 99%

Which of the following specific elements of the patient's recent medical history is most critical to elicit to establish the underlying diagnosis?

A 29-year-old man presents to an outpatient clinic with a 5-day history of fever, severe pharyngitis, profound fatigue, and a nonpruritic maculopapular rash on his trunk and extremities. He has no significant past medical history. Social history is notable for unprotected receptive anal intercourse with a new male partner 16 days ago. His temperature is 38.3°C (100.9°F), blood pressure is 118/76 mmHg, pulse is 102/min, and respirations are 16/min. Physical examination reveals generalized cervical and axillary lymphadenopathy. The physician suspects acute retroviral syndrome and initiates the standard diagnostic algorithm and pre-treatment evaluation.

Arrange the following laboratory tests in the most appropriate chronological sequence for establishing the definitive diagnosis, evaluating the baseline disease state, and preparing for the initiation of antiretroviral therapy.

A $28$-year-old woman is evaluated in the clinic for a $6$-month history of extreme fatigue, abdominal bloating, and frequent, bulky, foul-smelling bowel movements. She has unintentionally lost $4.5$ kg ($10$ lb) during this period. Her medical history is significant for three distinct episodes of acute bacterial sinusitis over the past year. She takes no medications and has no known drug allergies. Vital signs are within normal limits. Physical examination reveals mild conjunctival pallor and a mildly distended abdomen with hyperactive bowel sounds. Initial laboratory testing shows:

Hemoglobin: $10.1$ g/dL
Mean corpuscular volume: $74$ fL
Ferritin: $8$ ng/mL (normal: $15$-$200$ ng/mL)
Tissue transglutaminase (tTG) IgA antibody: Negative
Total serum IgA: $4$ mg/dL (normal: $70$-$400$ mg/dL)

Which of the following is the most appropriate next step in laboratory evaluation?