Diagnostic Test Interpretation

A 33-year-old man with intermittent asthma presented with 3 months of dyspnea on exertion, which developed approximately 2 weeks after infection with SARS-CoV-2. The patient demonstrated reduced exercise tolerance during cardiopulmonary testing, achieving only 64% of the predicted maximum rate of oxygen consumption. How do you interpret these test results?

A 36-year-old man received a 0.9% saline infusion as postoperative treatment after a transsphenoidal resection of a pituitary macroadenoma. Within 30 minutes in the recovery room, he developed persistent, large-volume urine output. Blood testing performed 6 hours after the operation showed a sodium value of 148 mEq/L, increased from a baseline level of 138 mEq/L. What would you do next?

A previously healthy 50-year-old woman presented with 3 weeks of fatigue, nausea, dark urine, pruritus, and scleral icterus. She had a serum aminotransferase value of 1198 U/L, antinuclear antibody titer of 1:160, and IgG concentration of 1940 mg/dL. What would you do next?

A 62-year-old man presented with a 4- to 6-month history of increasing exertional dyspnea. His measured hemoglobin was 15.3 g/dL and diffusing capacity of the lungs for carbon monoxide was 9.80 mL/min/mm Hg. How would you interpret these test results?

A 27-year-old woman presented with elevated transaminase levels and a positive hepatitis B surface antigen test result. How do you interpret these test results?

A 50-year-old woman with a history of seizures presented to the electromyography laboratory with progressive lower extremity pain and gait imbalance. Results of nerve conduction studies showed an absent sural sensory response and decreased amplitudes of peroneal motor and radial sensory responses. How do you interpret these results?

A 53-year-old woman presented to the gastroenterology clinic for endoscopy because of submucosal gastric nodule. Reverse transcriptase–polymerase chain reaction SARS-CoV-2 testing before the procedure was positive, and the patient reported testing positive for SARS-CoV-2 30 days prior. What would you do next?

This case report describes the evaluation of a 52-year-old woman taking a thiazide diuretic with hypokalemia (potassium, 2.6 mEq/L) and hypertension (blood pressure, 159/94 mm Hg) and presents an algorithm for the diagnosis and management of underlying causes of low serum potassium levels.

A 64-year-old man underwent APOE ɛ4 allele testing for 3 years of forgetfulness and word-finding difficulties and a family history of early-onset dementia, with results positive for genotypes 3 and 4 indicating “with high specificity, that Alzheimer’s disease is the cause of or a contributor to the observed dementia.” What would you do next?

A 63-year-old woman with type 2 diabetes was referred for refractory hypomagnesemia (1.4 mg/dL; low normal, 1.8 mg/dL). Her medications included liraglutide, metformin, lisinopril, and magnesium oxide (400 mg twice daily). A recent hemoglobin A_1c level was 10.8%, and her urinary magnesium was 117 mg. How do you interpret the urine level, and what would you do next?

A 56-year-old woman with a history of CAD, hypertension controlled with medication, and a recent negative stress ECG for atypical chest pain underwent coronary CTA for persistent symptoms, which showed no stenosis or plaque. How would you follow up on the negative imaging result?

A 61-year-old woman with a history of hypertension presented for evaluation of exertional left calf discomfort. Her lower extremity systolic blood pressure and ankle-brachial index (ABI) measures declined after treadmill testing. What would you do next?

An 18-year-old man who recently emigrated from India presented with fever, malaise, and anorexia for 4 days. He was afebrile with scleral icterus and a palpable liver edge; had a white blood cell count of 3.9 × 10³/μL with elevations in total and direct bilirubin, alkaline phosphatase, and liver enzymes; and laboratory test results were positive for HBsAg and HBV core IgG. What is the cause of his hepatitis, and what would you do next?

A 40-year-old woman with Graves disease presented with abdominal pain and constipation. Thyroid-stimulating hormone was undetectable and physical examination revealed a tender midline abdominal mass. Three months earlier she was evaluated for 3 to 4 months of amenorrhea, and a urine human chorionic gonadotropin test was negative for pregnancy. What would you do next?

A 59-year-old man taking warfarin for recurrent VTE has a point-of-care (POC) international normalized ratio (INR) value of 3.7 (target 2.0 to 3.0). What would you do next?

An asymptomatic 57-year-old man with obesity, hypertension, and dyslipidemia requests screening for diabetes. Would you offer laboratory-based or point-of-care glucose or HbA_1c testing?

A 37-year-old woman with a history of depression and Roux-en-Y gastric bypass 16 years earlier presented with chronic fatigue, weight loss, irregular periods lasting 7 to 10 days, a vitamin B₁₂ level of 149 pg/mL, and an iron level of 13 µg/dL. She reported a daily total calorie intake of less than 500 kcal and less than 20 g of protein. How do you interpret these results?

A 65-year-old man from Vietnam presented with shortness of breath at rest, orthopnea, and lower extremity edema for the past 2 weeks and nonproductive cough and weight loss for the past 4 months. A computed tomographic (CT) scan demonstrated a moderate to large pericardial effusion that was lymphocyte-predominant with a fluid ADA level of 118.1 U/L. What would you do next?