All practice questions

Which of the following laboratory evaluations is the most appropriate initial diagnostic step for each patient presentation? Match each clinical vignette with its indicated targeted initial laboratory test.

Severe, colicky abdominal pain and altered mental status prompt the emergency department evaluation of a 42-year-old man. According to his husband, the patient has experienced two months of progressive fatigue, intractable constipation, and diffuse joint pains. His past medical history includes essential hypertension and bilateral knee osteoarthritis. Current medications consist of hydrochlorothiazide and ibuprofen, the latter taken frequently for joint discomfort. He underwent an uncomplicated appendectomy in childhood. The patient resides in a suburban home built in 1995, consumes one glass of wine weekly, and does not use tobacco or illicit drugs. He works as a high school teacher and his primary hobby is restoring antique stained glass windows in his poorly ventilated basement. Upon examination, his blood pressure is 158/94 mm Hg, heart rate is 88/min, and temperature is 37.1°C (98.8°F). The abdomen is diffusely tender to palpation with no rebound or guarding. Neurological examination reveals delayed cognitive processing and bilateral weakness in wrist extension (3/5 strength). Laboratory evaluation demonstrates a hemoglobin level of 9.1 g/dL with a mean corpuscular volume of 73 fL, and a normal serum creatinine of 0.9 mg/dL. Which of the following elements from the patient's history is most likely responsible for his current clinical presentation?

Below are descriptions of biopsy or autopsy findings from four different patients. Correlate each clinical and histopathological description with its primary subcellular mechanism of injury or adaptation.

A 72-year-old woman is brought to the clinic by her son for a routine follow-up. She has a history of a massive ischemic stroke 8 months ago involving the right middle cerebral artery territory, which resulted in dense left-sided hemiplegia. Since the stroke, she has been bedbound and non-weight-bearing on her left side despite physical therapy efforts. Her current medications include aspirin, atorvastatin, and lisinopril. On physical examination, her vital signs are within normal limits. There is marked asymmetry of her lower extremities; her left thigh and calf circumferences are significantly smaller than those on the right. Deep tendon reflexes are 3+ on the left and 2+ on the right, with a positive Babinski sign on the left. The skin on the left leg is intact with no erythema, edema, or calf tenderness. Which of the following subcellular processes is most directly responsible for the reduction in muscle mass observed in this patient's left lower extremity?

A 71-year-old retired accountant is evaluated in the neurology clinic for recurrent, unprovoked backward falls and a progressive slowing of movements over the past year. His family reports that his voice has become increasingly monotonic, and he frequently spills food because he 'cannot look down' at his plate. On mental status examination, he exhibits mild executive dysfunction. The physician suspects progressive supranuclear palsy. Which of the following specific physical examination findings would best confirm this diagnosis and differentiate it from other parkinsonian syndromes? (Select TWO that apply)

A 61-year-old woman is evaluated in a hepatology clinic for progressive abdominal swelling and early satiety over the past three months. She also reports worsening bilateral lower extremity edema and exertional fatigue. Her medical history is significant for Hodgkin lymphoma diagnosed at age 25, which was treated with mantle field radiation and multi-agent chemotherapy. She takes no medications and does not consume alcohol. Vital signs are temperature 37.0°C (98.6°F), blood pressure 110/70 mm Hg, heart rate 88/min, and respiratory rate 16/min. Abdominal ultrasound demonstrates a nodular liver, moderate ascites, and splenomegaly, with normal hepatic vein Doppler flow. Based on the most likely underlying etiology of her symptoms, which of the following physical examination findings are expected in this patient? (Select 3 that apply)

Match the following distinctive abdominal and gastrointestinal physical examination signs with their corresponding underlying pathophysiological mechanism or specific clinical etiology.

A 28-year-old woman is hospitalized for a severe flare of systemic lupus erythematosus, characterized by a malar rash, inflammatory polyarthritis, and new-onset proteinuria. Laboratory studies on admission reveal a serum creatinine of 1.8 mg/dL and an absolute lymphocyte count of 1,800/mm³. She is initiated on high-dose intravenous methylprednisolone therapy to manage the acute exacerbation. Five days later, her total leukocyte count remains stable, but her absolute lymphocyte count has decreased precipitously to 550/mm³. A peripheral blood smear shows normal red blood cell morphology, adequate platelets, and no abnormal lymphoid forms, schistocytes, or blasts. Which of the following best describes the fundamental cellular mechanism responsible for the rapid decline in this patient's lymphocyte count?

Match each patient's clinical presentation with the most appropriate initial diagnostic laboratory test to order.

A 28-year-old woman comes to the clinic reporting a 3-month history of generalized fatigue and decreased exercise tolerance. She notes feeling winded after climbing a single flight of stairs. Her menstrual cycles are regular but last 7 days with heavy bleeding, requiring her to change a high-absorbency pad every 2 hours during the first three days. She has followed a strict vegan diet for the past two years. Her vital signs are temperature 36.8°C (98.2°F), blood pressure 110/70 mm Hg, pulse 88/min, and respirations 14/min. Physical examination shows pale conjunctivae but no scleral icterus, organomegaly, or lymphadenopathy. A complete blood count reveals a hemoglobin level of 10.1 g/dL and a mean corpuscular volume (MCV) of 72 fL. Which of the following is the most appropriate next step in laboratory evaluation?

A 48-year-old woman is undergoing a course of adjuvant localized radiotherapy following a lumpectomy for invasive ductal carcinoma of the breast. The targeted high-energy radiation is intended to eradicate any residual microscopic disease by inducing irreversible cellular injury in the rapidly dividing neoplastic cells. Arrange the following subcellular events in the chronological order that leads to the death of the targeted cells.

An $80\text{-kg}$, 65-year-old male is transferred to the intensive care unit due to septic shock. The critical care team decides to rapidly initiate broad-spectrum antibiotic therapy, which includes a novel antimicrobial, Drug X. The clinical pharmacist provides the following pharmacokinetic parameters for Drug X in critically ill adults:

- Volume of distribution ($V_d$): $0.5 \text{ L/kg}$
- Systemic clearance ($Cl$): $2.0 \text{ L/hr}$
- Oral bioavailability ($F$): $80\%$

The target peak plasma concentration ($C_p$) required for therapeutic efficacy against the suspected pathogen is $20 \text{ mg/L}$. To rapidly achieve this target level, an intravenous loading dose is ordered.

What intravenous loading dose (in mg) should be administered to this patient?

An asymptomatic 55-year-old woman presents for an annual health maintenance visit. She reports feeling well with excellent energy levels, a stable weight, and regular bowel movements. Her only chronic medical condition is mild essential hypertension, which is managed effectively with lisinopril. Her vital signs are within normal limits. On physical examination, her thyroid gland is normal in size, non-tender, and without palpable nodules. The remainder of the physical examination is unremarkable. Routine thyroid function testing reveals the following:

Thyroid-stimulating hormone (TSH): 7.5 µU/mL (Reference: 0.4-4.0 µU/mL)
Free thyroxine (T4): 1.3 ng/dL (Reference: 0.9-1.7 ng/dL)

Which of the following is the most accurate diagnosis based on these laboratory results?

A 25-year-old man comes to the clinic reporting a 10-day history of fever, sore throat, severe fatigue, and a generalized rash. He reports unprotected sexual intercourse with a new male partner approximately 3 weeks ago. His temperature is 38.2°C (100.8°F). Physical examination reveals bilateral cervical lymphadenopathy and a faint, nonpruritic, erythematous macular rash on the trunk. The physician suspects acute human immunodeficiency virus (HIV) infection. Arrange the following laboratory tests in the most appropriate sequential order to establish the diagnosis, according to the standard evidence-based diagnostic testing algorithm.

A 65-year-old man weighing $80 \text{ kg}$ is admitted to the intensive care unit with a severe, drug-resistant gram-negative bacteremia. The infectious disease consultant recommends starting a continuous intravenous infusion of a novel bactericidal antibiotic. The target steady-state plasma concentration ($C_{ss}$) for efficacy is $5 \text{ mg/L}$.

The population pharmacokinetic parameters for this antibiotic in healthy individuals with normal renal function (creatinine clearance $\approx 120 \text{ mL/min}$) are:
- Volume of distribution ($V_d$): $1.5 \text{ L/kg}$
- Systemic clearance ($CL$): $0.6 \text{ L/hr/kg}$

The drug is eliminated entirely unchanged in the urine, and its systemic clearance is directly proportional to creatinine clearance. The patient's estimated creatinine clearance is $60 \text{ mL/min}$. The patient's extracellular fluid volume is clinically normal.

Based on these parameters, which of the following represents the most appropriate loading dose and continuous maintenance infusion rate for this patient?

During morning rounds on the medical ward, a physician evaluates a 59-year-old woman who was admitted overnight for high fever, profound fatigue, and painful mouth sores. The patient reports that her symptoms started 4 days ago and have progressively worsened, accompanied by a noticeable decrease in urine output.

Her past medical history is notable for seropositive rheumatoid arthritis, which has been well-controlled for 4 years on a stable regimen of weekly methotrexate and daily folic acid (2 mg). She also has hypertension and type 2 diabetes mellitus, managed with lisinopril and metformin. Surgical history includes an uncomplicated cholecystectomy 10 years ago.

When taking a detailed interval history, the physician discovers several recent events. Six weeks ago, she traveled to rural Ohio to visit relatives and spent a day exploring local caves. Three weeks ago, seeking to 'boost her immune system', she began taking an over-the-counter echinacea extract. Two weeks ago, she developed dysuria and urinary frequency; she visited a local urgent care clinic and completed a 7-day course of trimethoprim-sulfamethoxazole, taking her last dose 5 days ago.

Vital signs are temperature 39.1°C (102.4°F), blood pressure 105/65 mm Hg, pulse 112/min, and respirations 18/min.

Physical examination is remarkable for extensive, coalescing, necrotic ulcerations on the buccal mucosa and soft palate. There is a diffuse petechial rash over the lower extremities. The abdomen is soft and non-tender without hepatosplenomegaly.

Laboratory results obtained on admission show:
Hemoglobin: 7.8 g/dL
Platelet count: 18,000/mm³
Leukocyte count: 1,200/mm³ (Absolute neutrophil count: 350/mm³)
Blood urea nitrogen: 52 mg/dL
Serum creatinine: 2.4 mg/dL (Baseline: 0.9 mg/dL)
Aspartate aminotransferase (AST): 210 U/L
Alanine aminotransferase (ALT): 195 U/L

Based on a meticulous evaluation of this patient's medical history, which of the following elements is the most direct cause of her current life-threatening presentation?

Match each patient's clinical presentation with the most appropriate next step in their diagnostic workup and test sequencing, according to established guidelines for pulmonary nodules and lung mass evaluation.

A 72-year-old female resident of a skilled nursing facility is brought to the emergency department due to sudden, severe, diffuse abdominal pain that began three hours ago. Her medical history is significant for hypertension, type 2 diabetes mellitus, chronic kidney disease stage 4 (baseline serum creatinine 2.8 mg/dL, eGFR 18 mL/min/1.73m²), and paroxysmal atrial fibrillation. She is not currently taking anticoagulants due to a history of recurrent falls. On arrival, her temperature is 37.6°C (99.7°F), blood pressure is 105/65 mm Hg, pulse is 118/min and irregularly irregular, and respiratory rate is 22/min. Physical examination reveals a soft, non-distended abdomen with minimal tenderness to deep palpation; there is no guarding or rebound tenderness. Bowel sounds are hypoactive. Initial laboratory studies show a white blood cell count of 16,500/mm³ and a serum lactate level of 4.8 mmol/L. Which of the following is the most appropriate next step in diagnostic imaging?

A 31-year-old man is brought to the trauma resuscitation bay following a high-speed motorcycle collision where he was thrown 30 feet. He is hemodynamically stable with a blood pressure of 118/78 mmHg and a heart rate of 105/min. His primary survey is intact. The secondary survey is notable for a mechanically unstable 'open book' pelvic fracture, significant perineal ecchymosis, and frank blood visible at the urethral meatus. A focused assessment with sonography for trauma (FAST) exam shows no free intraperitoneal fluid. Urinalysis from a spontaneously voided small sample prior to arrival showed gross hematuria.

Arrange the following diagnostic imaging steps in the correct mandated sequence to properly evaluate this patient's genitourinary injuries while minimizing iatrogenic harm and diagnostic artifact.

A 72-year-old woman is brought to the emergency department at 07:00 by emergency medical services. Her husband found her awake but with profound right-sided weakness and an inability to speak when they woke up at 06:30. She was last known well at 22:30 the previous night. On presentation, her blood pressure is 165/90 mm Hg and her heart rate is 88/min and irregularly irregular. Neurologic examination reveals global aphasia, a right facial droop, and right hemiplegia (NIH Stroke Scale score of 18).

Arrange the following neuroimaging modalities and interventional procedures in the most appropriate step-wise sequence for evaluating this patient for acute reperfusion therapy.