All practice questions

Investigators are analyzing data from a national health registry to assess the safety profile of a recently introduced calcitonin gene-related peptide (CGRP) antagonist used for acute migraine treatment. Specifically, they are evaluating the incidence of ischemic stroke over a 5-year period among 15,000 adult patients. Initial unadjusted analysis reveals that patients using the CGRP antagonist have a higher risk of ischemic stroke compared to those using standard NSAID therapy, yielding a relative risk (RR) of 1.7 ($p = 0.03$). Suspecting that underlying patient characteristics might be influencing these results, the analysts separate the cohort into two groups: those with a documented history of migraine with aura and those without aura. Upon re-evaluating the data, the RR for ischemic stroke among patients with migraine with aura is 3.1 ($p < 0.01$). Conversely, among patients without aura, the RR is 1.02 ($p = 0.88$). Which of the following epidemiological phenomena best explains the function of the 'migraine with aura' variable in this analysis?

Below are four distinct methodological observations from recent clinical studies. Pair each specific study finding with the corresponding epidemiological phenomenon that best explains it.

A 52-year-old man is evaluated in the outpatient clinic for a 3-week history of generalized muscle weakness, severe leg cramps, and intermittent headaches. He has a past medical history of essential hypertension and gastroesophageal reflux disease. His prescribed medications include amlodipine and famotidine. During the clinical interview, the patient states that he recently discontinued famotidine and began consuming large quantities of a "traditional botanical tea" to naturally manage his frequent heartburn.

Vital signs show a blood pressure of 172/105 mmHg and a pulse of 78/min. Physical examination is unremarkable except for trace bilateral pedal edema.

Laboratory studies reveal:
Serum sodium: 146 mEq/L
Serum potassium: 2.7 mEq/L
Serum chloride: 102 mEq/L
Serum bicarbonate: 32 mEq/L

Which of the following components of the patient's history is the most likely underlying cause of his current clinical and laboratory presentation?

A 45-year-old woman is evaluated in the emergency department for a sudden onset of palpitations, severe anxiety, and diaphoresis that began 2 hours ago. She has a history of major depressive disorder, for which she is prescribed sertraline, and obesity. She reports that she recently started a new intensive health regimen to lose weight for an upcoming family event. Her temperature is 38.2°C (100.8°F), blood pressure is 168/104 mm Hg, pulse is 128/min, and respirations are 22/min. Physical examination reveals mydriasis, diaphoresis, hyperreflexia in the lower extremities, and a fine bilateral tremor. Which of the following historical elements are most critical to elicit to determine the etiology of her current presentation? (Select all that apply)

For each of the following specific patient encounters, select the most appropriate targeted laboratory investigation required to establish the diagnosis.

A 26-year-old woman is evaluated in the outpatient clinic for a recent episode of syncope. Yesterday, while jogging on a local trail, she experienced sudden lightheadedness followed by a complete loss of consciousness. She was found by a bystander and regained consciousness within 1 to 2 minutes without postictal confusion or focal deficits. Past medical history is unremarkable. She has no prior surgical history. She takes no prescription medications, and her medication history is negative for daily over-the-counter supplements. Social history is negative for tobacco, alcohol, or illicit substance use. Family history is notable for the sudden death of her maternal uncle at age 32 in a single-car motor vehicle accident. Her temperature is 37.0°C (98.6°F), blood pressure is 112/70 mmHg, pulse is 72/min, and respiratory rate is 14/min. Physical examination, including a detailed neurological and cardiovascular assessment, is completely normal. A 12-lead electrocardiogram demonstrates normal sinus rhythm, a normal axis, a QTc interval of 420 ms, and no evidence of ventricular hypertrophy or ST-T wave changes. Which of the following additional historical details is most important to ascertain to prioritize the differential diagnosis?

An outpatient consultation is requested for a patient experiencing persistent, voluminous diarrhea and burning epigastric pain that frequently awakens them at night. An esophagogastroduodenoscopy performed three weeks ago demonstrated prominent gastric folds and multiple ulcerations extending into the second portion of the duodenum. Symptoms have persisted despite strict adherence to high-dose proton pump inhibitor therapy. The patient is instructed to appropriately discontinue the acid-suppressing medication, after which laboratory evaluation reveals a fasting serum gastrin level of 650 pg/mL (reference range: < 100 pg/mL) alongside a basal gastric pH of 1.5. Which of the following is the most appropriate next step in the diagnostic evaluation to establish the etiology of this patient's condition?

Review the following patient presentations characterizing different forms of pelvic pathology. Match each patient's distinct historical and clinical profile with the most likely underlying diagnosis.

A $42$-year-old woman is evaluated in the hospital for persistent fever. She was admitted two days ago with right-sided flank pain, dysuria, and a temperature of $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$). Her medical history is significant for complex partial seizures, which have been well-controlled on valproic acid for the past five years, and type $2$ diabetes mellitus. Upon admission, she was started on empiric intravenous ceftriaxone for severe pyelonephritis.

Today, her temperature is $38.9^\circ\text{C}$ ($102.0^\circ\text{F}$), blood pressure is $105/65 \text{ mmHg}$, heart rate is $112 \text{ bpm}$, and respiratory rate is $18/\text{min}$. Laboratory studies show a serum creatinine of $1.9 \text{ mg/dL}$ (baseline $0.8 \text{ mg/dL}$).

Blood and urine cultures drawn on admission are both growing *Escherichia coli*. The microbiology laboratory confirms that the isolate is an extended-spectrum beta-lactamase (ESBL) producer. The susceptibility profile is as follows:

Ceftriaxone: Resistant
Cefepime: Resistant
Piperacillin-tazobactam: Susceptible
Meropenem: Susceptible
Amikacin: Susceptible

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

A 28-year-old man comes to the clinic for sexually transmitted infection screening. He reports engaging in unprotected receptive anal intercourse with a new male partner approximately 3 weeks ago. He is currently asymptomatic and his physical examination is unremarkable. The physician suspects a potential acute HIV infection and initiates the diagnostic workup. Arrange the following laboratory steps in the correct chronological sequence for diagnosing and initially evaluating this patient according to standard HIV testing guidelines.

Emergency medical services bring a 24-year-old female to the emergency department because of altered mental status and reported ringing in her ears. According to her roommate, the patient was found in her bedroom surrounded by several empty bottles of over-the-counter analgesics. On physical examination, she is diaphoretic and confused. Her temperature is 37.8°C (100.0°F), pulse is 118/min, respirations are 30/min, and blood pressure is 112/68 mm Hg. The lungs are clear to auscultation. A radial artery blood sample and a peripheral venous blood sample are drawn. Laboratory results are as follows:

Arterial blood gas (room air)
$\text{pH}$: 7.42
$\text{PaO}_2$: 98 mm Hg
$\text{PaCO}_2$: 20 mm Hg
$\text{HCO}_3^-$: 13 mEq/L

Serum chemistries
Sodium: 140 mEq/L
Potassium: 3.8 mEq/L
Chloride: 104 mEq/L
Bicarbonate: 13 mEq/L
Blood urea nitrogen: 16 mg/dL
Creatinine: 0.9 mg/dL

Which of the following is the most accurate interpretation of this patient's acid-base laboratory results?

A previously healthy 28-year-old woman comes to the primary care clinic complaining of frequent loose stools for the past two months. She experiences 3 to 5 episodes of watery diarrhea daily, accompanied by significant abdominal bloating and flatulence. The patient notes that her symptoms completely resolve on days when she fasts for religious reasons. She denies any nocturnal symptoms, fever, weight loss, or gross blood in her stool. She has no chronic medical conditions and takes no prescription medications, but mentions she recently overhauled her lifestyle and diet to lose weight. Her vital signs and physical examination show no abnormalities. Comprehensive metabolic panel, complete blood count, and thyroid function tests are within reference ranges. Stool testing is negative for occult blood, bacterial pathogens, and parasites. However, a stool electrolyte analysis demonstrates a fecal osmotic gap of 115 mOsm/kg (normal: < 50 mOsm/kg). Asking the patient about which of the following habits or exposures is the most appropriate next step to establish the diagnosis?

A 72-year-old man with a history of hypertension and atrial fibrillation presents to the emergency department with severe, diffuse abdominal pain that began suddenly 2 hours ago. He admits to missing his prescribed oral anticoagulant doses for the past week. He reports one episode of bloody diarrhea shortly after the pain started. On physical examination, his abdomen is soft, non-distended, and remarkably non-tender to deep palpation despite his severe distress. Vital signs are temperature 37.1 C (98.8 F), blood pressure 110/70 mmHg, heart rate 115/min and irregularly irregular, and respiratory rate 22/min.

Based on this patient's clinical presentation, arrange the following differential diagnoses from the highest pre-test probability (most likely) to the lowest pre-test probability (least likely).

A 64-year-old man is evaluated in the intensive care unit for sudden-onset hemodynamic instability. The patient was admitted three days ago for severe community-acquired pneumonia complicated by acute respiratory distress syndrome (ARDS) and has been receiving mechanical ventilation with high positive end-expiratory pressure (PEEP). Two minutes ago, the ventilator's high-pressure alarm began sounding continuously. His temperature is 37.8°C (100.0°F), blood pressure is 65/40 mm Hg, pulse is 138/min, and respirations are set at 18/min but the patient is dyssynchronous. Oxygen saturation is 78% on a fraction of inspired oxygen (FiO2) of 0.80. Physical examination reveals distended neck veins, tracheal deviation to the left, and absent breath sounds over the right hemithorax. Which of the following is the single most urgent initial stabilization step?

A $56$-year-old woman is brought to the emergency department by her husband due to rapidly progressive pain, swelling, and redness of her left lower leg over the past $24$ hours. She has a history of type 2 diabetes mellitus and peripheral neuropathy. She felt feverish earlier today and experienced a single episode of vomiting. On triage, her temperature is $39.2^{\circ}\mathrm{C}$ ($102.6^{\circ}\mathrm{F}$), blood pressure is $88/54\mathrm{\ mmHg}$, pulse is $122/\mathrm{min}$, and respirations are $24/\mathrm{min}$. Physical examination reveals an ill-appearing patient. The left lower extremity demonstrates diffuse, poorly demarcated erythema and tense edema extending from the ankle to the proximal calf. There are distinct violaceous bullae present on the anterior shin. Palpation of the leg elicits exquisite pain out of proportion to the visible skin changes, and faint crepitus is noted. Laboratory studies show a leukocyte count of $24,500/\mathrm{mm}^3$ with $18\%$ bandemia, a serum sodium level of $130\mathrm{\ mEq/L}$, and a serum creatinine of $2.1\mathrm{\ mg/dL}$. Which of the following are the most appropriate immediate steps in the management of this patient? (Select all that apply)

A 62-year-old man with a 15-year history of poorly controlled type 2 diabetes mellitus and peripheral neuropathy presents to the outpatient clinic with a non-healing ulcer on the plantar aspect of his left foot. The ulcer has been present for four weeks. Physical examination reveals a 2-cm, clean-based ulcer under the first metatarsal head surrounded by a 1-cm rim of erythema and mild edema. There is no purulent discharge. A sterile blunt probe is inserted into the ulcer but does not reach the bone. The patient is afebrile, and his vital signs are within normal limits.

Arrange the following diagnostic and therapeutic steps in the most appropriate chronological sequence for evaluating and managing this patient's condition.

A 48-year-old man is evaluated in the clinic for persistently elevated blood pressure. He was diagnosed with hypertension three years ago. His current medications include maximally tolerated doses of amlodipine, lisinopril, and doxazosin. He reports no headaches, palpitations, or diaphoresis. Vital signs are significant for a blood pressure of 168/98 mm Hg and a heart rate of 76/min. Physical examination is unremarkable, and no abdominal bruits are auscultated.

Current laboratory studies:
Sodium: 144 mEq/L
Potassium: 2.8 mEq/L
Chloride: 102 mEq/L
Bicarbonate: 29 mEq/L
Creatinine: 0.9 mg/dL

A review of his medical records indicates that his potassium was 3.1 mEq/L prior to the initiation of any antihypertensive therapy. Due to high clinical suspicion for secondary hypertension, hormonal screening is obtained:

Plasma renin activity (PRA): 0.2 ng/mL/h (Normal: 0.6 - 4.3 ng/mL/h)
Plasma aldosterone concentration (PAC): 28 ng/dL (Normal: 4 - 21 ng/dL)

Which of the following is the most appropriate next step in the diagnostic workup?

A 34-year-old woman is evaluated in the medical ward for severe community-acquired pneumonia. Over the past 24 hours, her clinical status has deteriorated, necessitating the initiation of vasopressors. While a physician is attempting to place a right internal jugular central venous catheter, the patient suddenly exhibits profound respiratory distress and her level of consciousness rapidly declines. Vital signs show a temperature of 38.8°C (101.8°F), blood pressure of 64/34 mmHg, heart rate of 148/min, and respiratory rate of 36/min. Oxygen saturation is 76% despite a non-rebreather mask. On physical examination, the trachea is visibly deviated to the left, and the jugular veins are markedly distended. Auscultation reveals absent breath sounds over the entire right hemithorax, with associated hyperresonance to percussion.

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

An 82-year-old man is evaluated in the intensive care unit for new-onset fever and abdominal distension. He was admitted 8 days ago for severe community-acquired pneumonia requiring endotracheal intubation and mechanical ventilation. His medical history is significant for coronary artery disease and heart failure with preserved ejection fraction. Current medications include propofol, fentanyl, and intravenous broad-spectrum antibiotics. Temperature is 38.9°C (102.0°F), blood pressure is 88/54 mm Hg (currently requiring a norepinephrine infusion), pulse is 118/min, and respirations are 18/min on the ventilator. Physical examination reveals a distended abdomen with guarding in the right upper quadrant. Laboratory studies show a leukocyte count of 22,000/mm³ and serum lactate of 4.1 mmol/L. Liver function tests show a normal total bilirubin and mildly elevated transaminases. A bedside right upper quadrant ultrasound reveals a thickened gallbladder wall measuring 6 mm, significant pericholecystic fluid, and absence of gallstones. The common bile duct is not dilated. Which of the following is the most appropriate next step in the procedural management of this patient?

A $58$-year-old man presents to the emergency department with a $12$-hour history of severe right knee pain and swelling. He reports the pain woke him up from sleep and is exacerbated by the weight of his bedsheets. His medical history is significant for HIV, hypertension, and chronic kidney disease stage 3a. His current medications include darunavir, cobicistat, emtricitabine, tenofovir alafenamide, lisinopril, and amlodipine. His viral load is undetectable, and his CD4 count is $620/\text{mm}^3$. Temperature is $37.6^\circ\text{C}$ ($99.7^\circ\text{F}$), blood pressure is $142/88\text{ mmHg}$, and pulse is $92/\text{min}$. Physical examination reveals a warm, erythematous, and exquisitely tender right knee with a noticeable effusion. Laboratory studies show a serum creatinine of $1.9\text{ mg/dL}$ (baseline $1.8\text{ mg/dL}$) and a serum uric acid level of $9.4\text{ mg/dL}$. Arthrocentesis yields cloudy yellow synovial fluid with a leukocyte count of $62,000/\text{mm}^3$ ($88\%$ neutrophils). Gram stain reveals no organisms. Polarized light microscopy of the fluid demonstrates needle-shaped, negatively birefringent crystals. Which of the following is the most appropriate initial pharmacologic intervention for this patient's acute joint condition?