All practice questions

Match each patient's clinical presentation with the most appropriate targeted laboratory test to confirm the underlying etiology or assess disease-specific risk.

A 28-year-old man of Mediterranean descent is admitted to the oncology unit for initiation of induction chemotherapy. He was recently diagnosed with a highly aggressive B-cell non-Hodgkin lymphoma characterized by a $t(8;14)$ chromosomal translocation. Baseline laboratory studies show a serum uric acid level of $11.5 \text{ mg/dL}$, lactate dehydrogenase of $1,250 \text{ U/L}$, and a serum creatinine of $1.1 \text{ mg/dL}$. To mitigate the risk of an impending oncologic emergency, the patient is administered a recombinant enzyme therapy that directly degrades uric acid into a highly soluble inactive metabolite. Forty-eight hours later, the patient develops sudden-onset fatigue, scleral icterus, and dark urine. His hemoglobin concentration has decreased from $14.2 \text{ g/dL}$ to $8.4 \text{ g/dL}$. A peripheral blood smear reveals the presence of bite cells. The medication that precipitated this patient's acute deterioration is absolutely contraindicated in individuals who have a primary hereditary inability to synthesize adequate amounts of which of the following molecules?

A 45-year-old man comes to the clinic for a routine follow-up examination of type 2 diabetes mellitus. His current regimen includes metformin and a newly added oral antihyperglycemic medication, which was started four weeks ago. The patient reports that his home fasting blood glucose readings have improved significantly. However, he has noticed that his shoes feel tighter and he has gained 2.5 kg (5.5 lb) since his last visit. He has a history of mild heart failure with preserved ejection fraction. Physical examination reveals 2+ bilateral pitting edema of the lower extremities. Laboratory studies show a fasting plasma glucose of 112 mg/dL. The physician realizes the new medication is responsible for the patient's fluid retention, which is exacerbating his underlying cardiac condition, and plans to discontinue it immediately. The discontinued drug most likely exerts its primary therapeutic effect by initially binding to which of the following cellular targets?

A 62-year-old woman is brought to the emergency department by her daughter due to severe shortness of breath and wheezing that began 24 hours ago. The patient has a history of mild intermittent asthma but has not required an albuterol inhaler in over a decade. Her past medical history is also notable for essential hypertension, hyperlipidemia, and a newly diagnosed ocular condition characterized by elevated intraocular pressure, for which she saw an ophthalmologist three weeks ago. She is a lifelong nonsmoker. Her current oral medications include amlodipine and atorvastatin. When asked about other medications, she initially states she takes nothing else, but upon targeted questioning regarding her recent ophthalmology visit, she confirms she started a new twice-daily eye drop three weeks ago. Temperature is 37.0°C (98.6°F), blood pressure is 122/76 mmHg, pulse is 52/min, and respirations are 24/min. Oxygen saturation is 91% on room air. Physical examination reveals diffuse bilateral wheezing with a prolonged expiratory phase. The skin is warm and dry, and the oral mucosa is moist. There is no excessive lacrimation, salivation, or abnormal bowel sounds. A detailed medical history reveals that the systemic absorption of her new eye medication is likely responsible for her current presentation. Which of the following is the primary mechanism of action of the most likely responsible medication?

Match each patient's clinical presentation of a suspected paraneoplastic syndrome with the most likely underlying neoplastic etiology and its associated pathophysiologic mechanism.

A 46-year-old man comes to the clinic for a follow-up visit regarding poorly controlled hypertension. Over the past 4 months, his blood pressure has consistently been in the 160s/100s mmHg despite adherence to maximum doses of amlodipine and lisinopril. He reports new-onset generalized muscle weakness, fatigue, and frequent urination. His medical history is significant for chronic dyspepsia, for which he recently began consuming large quantities of a European herbal black candy. He does not use tobacco or illicit drugs. Blood pressure is $168/98$ mmHg, and pulse is 78/min. Physical examination reveals no edema, normal secondary sexual characteristics, and no striae or easy bruising.

Laboratory studies show:
Serum sodium: 146 mEq/L
Serum potassium: 2.5 mEq/L
Serum chloride: 101 mEq/L
Serum bicarbonate: 32 mEq/L
Plasma renin activity: 0.1 ng/mL/hr (normal: 0.6-4.3 ng/mL/hr)
Plasma aldosterone: 1.2 ng/dL (normal: 3.0-30.0 ng/dL)
Morning serum cortisol: 16 $\mu$ g/dL (normal: 5-23 $\mu$ g/dL)

Which of the following best describes the specific molecular mechanism responsible for this patient's clinical and laboratory presentation?

A $29$-year-old woman is evaluated in the clinic during a routine health maintenance examination. She has no symptoms of fatigue, abdominal pain, bone pain, or changes in urination. Her past medical history is unremarkable, and she takes no medications. Family history is significant for a maternal aunt who underwent neck surgery for an unspecified "calcium problem" in her $30$ s, though the patient states her aunt continues to have abnormal laboratory tests following the procedure. Vital signs are normal. Physical examination reveals a well-appearing patient with a normal thyroid gland and no palpable neck masses.

Laboratory evaluation shows:

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

A 39-year-old male is evaluated in the outpatient clinic for a four-month history of progressive tingling and burning pain in both feet. The symptoms are worse at night and frequently disrupt his sleep. He rarely visits healthcare providers and brings no medical records. Vital signs are within normal limits. His body mass index is 22 kg/m². Neurologic examination demonstrates diminished pinprick and vibratory sensation in a stocking distribution bilaterally, with absent ankle stretch reflexes. Motor strength is preserved in all extremities. To prioritize the differential diagnosis and guide subsequent laboratory testing, which of the following elements of the patient's medical history are essential to elicit? (Select all that apply)

A comprehensive medical history, including the use of over-the-counter (OTC) products and dietary supplements, is essential for identifying occult toxicities. Match each patient's clinical presentation, derived from their specific exposure history, with the most accurate underlying pathophysiologic etiology.

A 22-year-old man presents to the gastroenterology clinic for evaluation of intermittent bright red blood per rectum over the past two months. He reports no abdominal pain, unexplained weight loss, or changes in stool caliber. His father died of metastatic colorectal cancer at age 38, and a paternal aunt underwent abdominal surgery for an unknown malignancy in her 30s. His temperature is 37.0°C (98.6°F), blood pressure is 118/76 mmHg, pulse is 72/min, and respirations are 14/min. Physical examination reveals a soft, non-tender abdomen without organomegaly. Digital rectal examination demonstrates normal sphincter tone with small amounts of bright red blood on the examining finger. Given his striking family history, a colonoscopy is performed and reveals over 150 small adenomatous polyps carpeting the entire colon and rectum. Biopsies of several polyps confirm tubular adenomas with low-grade dysplasia. Which of the following best describes the underlying foundational mechanism of this patient's condition and the most appropriate definitive management?

A hospital laboratory is reviewing several distinct metabolic profiles of patients with disorders of calcium homeostasis. Match each patient's serum and urine biochemical profile to the most likely underlying pathophysiological mechanism.

A 30-year-old healthcare worker is undergoing routine employee health screening. As part of a clinic educational review, various patient Hepatitis B serologic panels are evaluated. Match each of the following Hepatitis B laboratory serologic patterns to the most accurate diagnostic interpretation.

An established patient in the primary care clinic, a 47-year-old male, is evaluated during a follow-up visit for difficult-to-control blood pressure. He reports taking his prescribed regimen of maximum-dose lisinopril, amlodipine, and chlorthalidone consistently. He occasionally experiences mild muscle cramps in his calves but otherwise feels well. Blood pressure is 164/96 mmHg and heart rate is 76/min. Physical examination is unremarkable with no abdominal bruits, edema, or focal neurological deficits. A basic metabolic panel reveals a serum sodium of 144 mEq/L, a serum potassium of 3.1 mEq/L, and a serum creatinine of 0.9 mg/dL. Which of the following is the most appropriate next step in the laboratory evaluation of this patient?

A 28-year-old woman is admitted to the medical ward with a 3-day history of high fever, marked facial swelling, and a widespread skin eruption. She reports that the rash began on her face and upper trunk before spreading to her extremities. Four weeks ago, she was prescribed sulfasalazine for newly diagnosed inflammatory bowel disease. Her temperature is 39.2°C (102.6°F), blood pressure is 110/70 mmHg, and pulse is 112/min. Physical examination reveals prominent periorbital edema, generalized cervical lymphadenopathy, and a diffuse, confluent, erythematous maculopapular rash covering 70% of her body surface area. There is no mucosal ulceration or epidermal detachment. Laboratory studies show:

Leukocyte count: $18,500/\text{mm}^3$
Eosinophils: $2,500/\text{mm}^3$ (normal: $15–500/\text{mm}^3$)
Alanine aminotransferase (ALT): 450 U/L
Aspartate aminotransferase (AST): 410 U/L
Serum creatinine: 1.1 mg/dL

Which of the following best describes the predominant immunopathologic mechanism driving this patient's clinical syndrome?

A $32$-year-old man comes to the clinic to establish care. He feels well and has no medical problems. He takes no medications. Vital signs are within normal limits. Routine laboratory testing reveals a serum calcium level of $11.2$ mg/dL (N: $8.4$-$10.2$ mg/dL) and a serum intact parathyroid hormone level of $55$ pg/mL (N: $15$-$65$ pg/mL). A $24$-hour urine collection shows a calcium excretion of $45$ mg/day (N: $100$-$300$ mg/day). The urine calcium-to-creatinine clearance ratio is calculated to be $0.005$ (normal $>0.02$). His mother also has a history of mild, asymptomatic hypercalcemia that was treated with a parathyroidectomy in her $30$ s without resolution of the hypercalcemia. Which of the following best describes the cellular mechanism underlying this patient's laboratory findings?

A 64-year-old man with a history of chronic obstructive pulmonary disease and long-standing alcohol use disorder is evaluated in the emergency department for progressive abdominal swelling, shortness of breath, and bilateral leg swelling over the past month. Vital signs show a blood pressure of 110/70 mmHg, a heart rate of 95/min, and a respiratory rate of 20/min. Oxygen saturation is 91% on room air. Physical examination reveals elevated jugular venous pulsation 9 cm above the sternal angle. Chest auscultation demonstrates distant breath sounds and expiratory wheezing bilaterally. The abdomen is markedly distended with shifting dullness and a positive fluid wave. There is 3+ pitting edema of the lower extremities up to the knees. Diagnostic paracentesis is performed, and laboratory results are as follows:

Serum
Total protein: 6.5 g/dL
Albumin: 3.4 g/dL
Total bilirubin: 1.8 mg/dL
Sodium: 135 mEq/L

Ascitic fluid
Color: Straw-colored, clear
Total protein: 3.1 g/dL
Albumin: 1.8 g/dL
White blood cell count: 210/mm³
Neutrophils: 15%
Lymphocytes: 45%

Based on the clinical presentation and laboratory findings, which of the following is the most likely underlying cause of this patient's ascites?

Match each patient's clinical presentation with the precise immunopathologic mechanism responsible for their condition.

A 44-year-old man presents to the oncology clinic for treatment planning of newly diagnosed metastatic colorectal cancer. He initially presented to his primary care physician with fatigue and was found to have iron deficiency anemia. A subsequent colonoscopy revealed a 3.5-cm ulcerated mass in the ascending colon, and a computed tomography scan of the abdomen and pelvis showed multiple hepatic metastases. His family history is notable for his father dying of colon cancer at age 48 and a paternal aunt who was treated for endometrial cancer at age 46.

Physical examination reveals pale conjunctivae and a palpable liver edge 3 cm below the right costal margin. Laboratory studies show a hemoglobin of 9.2 g/dL.

Biopsy of the hepatic lesion confirms metastatic adenocarcinoma. Immunohistochemical staining of the biopsy specimen demonstrates intact expression of MLH1 and PMS2 proteins, but absent expression of MSH2 and MSH6 proteins. The oncologist recommends initiating therapy with a programmed cell death protein 1 (PD-1) inhibitor.

Which of the following molecular characteristics best explains why this patient's neoplasm is highly susceptible to this specific pharmacologic therapy?

A 32-year-old woman with severe symptomatic iron deficiency anemia is admitted to the hospital and started on a transfusion of packed red blood cells. Fifteen minutes after the transfusion is initiated, she acutely develops chills, severe lower back pain, and a feeling of impending doom. Her temperature is 39.1°C (102.4°F), blood pressure is 88/54 mm Hg, heart rate is 124/min, and respiratory rate is 24/min. Physical examination reveals flushing and diaphoresis. An acute hemolytic transfusion reaction is suspected. Arrange the following steps in the most appropriate chronological sequence for the immediate management and diagnostic workup of this patient.

During a routine outpatient clinic visit, a $58$-year-old male patient reports a $2$-month history of progressive, deep, aching pain in his shins and wrists. He also describes worsening generalized fatigue and a $4\text{-kg}$ ($9\text{-lb}$) weight loss over the same period. He has a $30\text{-pack-year}$ smoking history and has not seen a physician in over a decade. Vital signs, including oxygen saturation on room air, are within normal limits. On physical examination, there is pronounced clubbing of the fingers and toes. There is bilateral, symmetrical, warm swelling of the wrists, metacarpophalangeal joints, and ankles. Deep palpation over the distal tibia and distal radius elicits exquisite periosteal tenderness. Cardiac auscultation reveals a regular rhythm with no murmurs, rubs, or gallops. Pulmonary examination demonstrates slightly decreased breath sounds at the right lung apex but is otherwise clear. Routine laboratory studies show a mild normocytic anemia and a borderline elevated rheumatoid factor of $24\text{ IU/mL}$ (normal $<20\text{ IU/mL}$). Based on this patient's specific constellation of physical examination findings, which of the following is the most appropriate next step in establishing the underlying diagnosis?