All practice questions

A 65-year-old man is evaluated in the hospital on postoperative day 7 following a right total knee arthroplasty. He has been receiving prophylactic subcutaneous enoxaparin since surgery. Today, a routine complete blood count shows a platelet count of 95,000/μL, representing a significant drop from his preoperative baseline of 280,000/μL. The patient also complains of new-onset right calf pain and swelling. Physical examination reveals unilateral right lower extremity edema, erythema, and tenderness to palpation.

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

A 74-year-old woman with unmedicated persistent atrial fibrillation is admitted with sudden-onset excruciating pain in her right lower extremity. Clinical evaluation reveals a cold, pale, and pulseless leg, highly suspicious for an acute thromboembolic occlusion of the superficial femoral artery. Place the following subcellular events in the correct chronological sequence as they occur within the ischemic skeletal myocytes during the resulting hypoxic injury.

A pharmacology research team is investigating 'Compound Y' as a potential therapeutic agent for chronic heart failure. They perform a series of *in vitro* experiments using isolated cardiac myocytes that express wild-type $\beta_1$-adrenergic receptors. The team measures intracellular cyclic AMP (cAMP) production as the downstream pharmacodynamic response.

In the first experiment, they plot a dose-response curve for dobutamine, a full $\beta_1$ agonist. They then add a fixed, moderate concentration of Compound Y and repeat the dobutamine dose-response curve. The new curve demonstrates an unchanged maximum cAMP production ($E_{max}$) but a significantly increased $EC_{50}$ for dobutamine.

In the second experiment, the myocytes are exposed to increasing concentrations of Compound Y alone. The researchers observe a dose-dependent increase in cAMP production, but the maximal response plateaus at exactly $40\%$ of the $E_{max}$ achieved by dobutamine.

In the third experiment, a maximal, saturating concentration of dobutamine is applied, producing a $100\%$ cAMP response. Increasing concentrations of Compound Y are then progressively added to this preparation.

Based on the receptor binding properties demonstrated in these experiments, what is the most likely outcome observed in the third experiment?

A 19-year-old collegiate athlete is evaluated in the clinic for pre-participation sports clearance. He is entirely asymptomatic and reports excellent exercise tolerance during rigorous training. His family history is highly notable for the sudden, unexplained death of his older brother at age 22 during a basketball game. The patient's temperature is 37.0°C (98.6°F), blood pressure is 112/68 mm Hg, and pulse is 62/min. Cardiac auscultation reveals a regular rate and rhythm with a grade 3/6 harsh, crescendo-decrescendo systolic murmur heard best at the left lower sternal border. The murmur does not radiate to the carotid arteries.

Which of the following dynamic physical examination maneuvers would most likely result in an INCREASE in the intensity of this patient's murmur?

A 29-year-old woman, G1P1, is evaluated in the intensive care unit on postpartum day 4 for worsening fatigue, confusion, and significantly decreased urine output. She had an uncomplicated spontaneous vaginal delivery at term.

Temperature is 37.6°C (99.7°F), blood pressure is 168/102 mm Hg, heart rate is 108/min, and respiratory rate is 18/min. Physical examination reveals scleral icterus and scattered petechiae over her lower extremities.

Laboratory studies show:

Peripheral blood smear shows numerous schistocytes.

Which of the following best describes the precise mechanism of the most appropriate targeted pharmacotherapy for this patient's underlying condition?

A 42-year-old woman is evaluated in the hospital on post-operative day 2 following a total thyroidectomy for papillary thyroid carcinoma. She reports new-onset tingling around her mouth and in her fingertips. Her temperature is 37.1°C (98.8°F), blood pressure is 118/76 mmHg, pulse is 82/min, and respirations are 14/min. The physician suspects a specific electrolyte abnormality related to her recent surgery. Which of the following physical examination maneuvers is most appropriate to demonstrate the expected physical finding for this condition?

A 78-year-old woman is evaluated in the hospital for severe, watery diarrhea, abdominal cramping, and fever. She was admitted 5 days ago for a community-acquired pneumonia treated with ceftriaxone and azithromycin. Temperature is 38.6°C (101.5°F), blood pressure is 90/60 mm Hg, and pulse is 112/min. Physical examination reveals a distended, diffusely tender abdomen with guarding. Laboratory studies show a leukocyte count of 28,000/mm³ and a serum creatinine of 1.9 mg/dL. Flexible sigmoidoscopy reveals raised, yellowish-white plaques adherent to the colonic mucosa. Stool testing is positive for a highly virulent organism's exotoxins. The patient's condition is primarily driven by bipartite large clostridial toxins. Arrange the following cellular events in the correct chronological pathophysiological sequence mediating this toxin's intracellular effect.

An attending physician is conducting bedside rounds in the infectious disease unit and discussing a newly admitted patient with a history of intravenous drug use. The patient presents with a two-week history of fever, fatigue, and a new-onset cardiac murmur, raising high clinical suspicion for infective endocarditis. The physician asks the medical team to evaluate for classic peripheral stigmata of this disease during the physical examination. Which of the following physical examination findings are highly characteristic of this condition? (Select all that apply.)

During a critical care rotation, a medical team is analyzing how different pharmacological interventions alter the dose-response curves of endogenous neurotransmitters or exogenous full agonists. Match each clinical drug scenario to the most accurate description of its pharmacodynamic effect on the primary agonist's dose-response curve.

A 62-year-old woman is evaluated on the inpatient medical ward for sudden clinical deterioration. She was admitted 4 days ago for a complicated urinary tract infection presenting with fever, right-sided flank pain, and dysuria. Initial urine cultures grew lactose-fermenting, indole-negative Gram-negative rods. Susceptibility testing demonstrated that the isolate was susceptible to ceftriaxone, cefepime, ciprofloxacin, and meropenem. She was started on intravenous ceftriaxone and initially showed clinical improvement, becoming afebrile by day 2. Today, she has developed recurrent chills and flank pain. Her temperature is $39.0^\circ\text{C}$ ($102.2^\circ\text{F}$), blood pressure is $90/55\text{ mmHg}$, and pulse is $112/\text{min}$. Repeat blood and urine cultures are drawn and subsequently grow the same organism. Susceptibility testing of the new isolate reveals resistance to ceftriaxone, but retained susceptibility to cefepime, ciprofloxacin, and meropenem. Which of the following molecular mechanisms most likely explains this pathogen's acquired resistance to the current antimicrobial therapy?

A 68-year-old man with a history of poorly controlled type 2 diabetes and hypertension is brought to the emergency department due to the sudden onset of severe, continuous room-spinning dizziness, intractable nausea, and difficulty walking that started 3 hours ago. He denies hearing loss, tinnitus, or headache. Blood pressure is 168/94 mmHg. On bedside evaluation, he exhibits spontaneous horizontal nystagmus that beats to the right on rightward gaze and to the left on leftward gaze. When the physician asks the patient to fixate on the physician's nose and rapidly rotates the patient's head to the right and left, the patient's eyes remain locked on the target without any refixation saccades. When an opaque card is alternately placed over each eye, there is a visible vertical refixation movement of the uncovered eye. Which of the following statements provides the most accurate interpretation of this patient's physical examination findings?

An infectious disease specialist is evaluating a male patient with multidrug-resistant bacteremia to design an appropriate antimicrobial dosing regimen.

Patient details:
- Age: $68$ years
- Weight: $72 \text{ kg}$
- Serum creatinine: $2.0 \text{ mg/dL}$ (stable over the past week)

The team plans to start a novel continuous intravenous antibiotic. Pharmacokinetic data indicates that this drug is excreted exclusively by glomerular filtration, and its clearance is directly equal to the patient's creatinine clearance. The target steady-state plasma concentration ($C_{ss}$) required for bactericidal efficacy is $15 \text{ mg/L}$.

Assuming the Cockcroft-Gault equation is $\text{CrCl} = \frac{(140 - \text{Age}) \times \text{Weight in kg}}{72 \times \text{Serum Creatinine in mg/dL}} \times (0.85 \text{ if female})$, what continuous intravenous infusion rate (in $\text{mg/hr}$) is required to achieve the target steady-state concentration?

A $72$-year-old man is brought to the emergency department by his family due to a rapidly expanding, painful swelling in his right thigh over the past $24$ hours. He denies any significant trauma, reporting only a minor bump against a doorway. His medical history is significant for rheumatoid arthritis and hypertension. Current medications include methotrexate, amlodipine, and occasionally ibuprofen.

Vital signs show a temperature of $37.1^\circ C$ ($98.8^\circ F$), heart rate of $118$/min, blood pressure of $98/62$ mmHg, and respiratory rate of $20$/min. Physical examination reveals a massive, tense, ecchymotic hematoma encompassing the right posterior thigh.

Laboratory studies are obtained:

A mixing study is performed using a $1:1$ ratio of the patient's plasma and normal pooled plasma. The aPTT immediately corrects to $32$ s. However, after incubation at $37^\circ C$ for $2$ hours, the aPTT prolongs to $82$ s.

The patient remains tachycardic, and the hematoma appears to be enlarging. Which of the following best describes the mechanism of action of the most appropriate immediate pharmacotherapy for this patient?

Evaluate the following four patient scenarios presenting with hematologic and coagulation abnormalities. For each clinical presentation, select the most accurate underlying pathophysiologic mechanism driving the disease process.

A 54-year-old man with a history of severe alcohol use disorder is brought to the emergency department due to the sudden onset of excruciating, band-like epigastric pain radiating to his back. He reports multiple episodes of nonbilious vomiting over the past 12 hours. On arrival, his temperature is 38.4°C (101.1°F), blood pressure is 92/58 mmHg, and heart rate is 122/min. Physical examination reveals scleral icterus and significant epigastric tenderness with involuntary guarding. Ecchymoses are noted around the umbilicus. Laboratory studies are as follows:

White blood cell count: 19,500/mm³
Total bilirubin: 3.2 mg/dL
Aspartate aminotransferase (AST): 310 U/L
Alanine aminotransferase (ALT): 145 U/L
Alkaline phosphatase: 210 U/L
Lipase: 4,800 U/L (normal: 10-140 U/L)
Total calcium: 6.8 mg/dL (normal: 8.4-10.2 mg/dL)
Albumin: 3.4 g/dL (normal: 3.5-5.0 g/dL)
Prothrombin time: 15 seconds (normal: 11-13 seconds)

An abdominal CT scan demonstrates diffuse pancreatic enlargement with indistinct margins and extensive peripancreatic fluid collections. Which of the following pathophysiological mechanisms is the primary cause of this patient's hypocalcemia?

A 29-year-old female medical resident presents to the employee health clinic with a 3-week history of unintentional weight loss, palpitations, and generalized anxiety. Physical examination reveals a resting heart rate of 110/min, a fine tremor in her outstretched hands, and a normal-sized, non-tender thyroid gland. Laboratory studies demonstrate a markedly suppressed thyroid-stimulating hormone (TSH) level and an elevated free thyroxine (T4) level. A subsequent radioactive iodine uptake scan reveals near-zero uptake. Which of the following historical inquiries is most essential to establishing the etiology of this patient's condition?

Match each patient's clinical presentation to the specific molecular mechanism of the responsible pathogen's primary virulence factor.

During a comprehensive medical history evaluation, clinicians must actively query patients regarding the use of over-the-counter botanical and herbal supplements, as patients frequently omit these from routine medication reconciliation. Match each patient's clinical presentation and intended supplement use with the responsible botanical agent and its underlying pathophysiologic mechanism.

A 61-year-old woman presents to the outpatient internal medicine clinic for the evaluation of progressive fatigue, lower extremity edema, and exertional dyspnea that have worsened over the last four months. During the clinical interview, the physician observes a sudden onset of violaceous flushing over her face and upper chest that resolves spontaneously after 10 minutes. The patient mentions a one-year history of episodic, explosive watery diarrhea and intermittent wheezing. On physical examination, her lungs are clear to auscultation bilaterally. Abdominal examination reveals a tender, enlarged liver with a distinct systolic pulsation. Which of the following physical examination findings are characteristically present in this patient's underlying cardiovascular condition? (Select all that apply)

A $62$-year-old man presents to the clinic for a routine follow-up. He has a history of end-stage renal disease (ESRD) requiring hemodialysis three times a week, as well as diet-controlled type $2$ diabetes mellitus. Two weeks ago, the patient was hospitalized for a generalized tonic-clonic seizure, which was successfully treated. He was discharged on a maintenance regimen of oral phenytoin $300$ mg daily. Since discharge, he has had no further seizure activity and reports no side effects such as dizziness or unsteadiness.

Vital signs are within normal limits. Neurological examination reveals no nystagmus, normal tandem gait, and an intact Mini-Mental State Examination.

Recent laboratory studies reveal the following:

Based on these findings, which of the following is the most appropriate next step in management?