Endocrine system (thyroid, adrenal, pancreas) — MCQs

A 60-year-old man with type 2 diabetes on metformin and insulin presents with 3 days of nausea, vomiting, and diffuse abdominal pain. He appears ill and confused. Vital signs: BP 95/60 mmHg, HR 115/min, RR 28/min, T 37.2°C. Labs show glucose 380 mg/dL, pH 7.28, HCO3 18 mEq/L, anion gap 24, serum osmolality 310 mOsm/kg, negative urine ketones, creatinine 2.8 mg/dL (baseline 1.1), lactate 8.2 mmol/L. Apply physiological principles to determine the primary acid-base and metabolic disturbance.

A 38-year-old woman presents with hypertension (170/105 mmHg), hypokalemia (2.9 mEq/L), and metabolic alkalosis. Plasma aldosterone is elevated at 35 ng/dL (normal 4-31) and plasma renin activity is suppressed at 0.2 ng/mL/hr (normal 0.5-3.5). CT scan shows a 2.5 cm left adrenal mass. She also reports recent diagnosis of hyperthyroidism and is being evaluated for a neck mass. Synthesize these findings to evaluate for an underlying unifying diagnosis requiring modified treatment approach.

A 32-year-old pregnant woman at 28 weeks gestation with type 1 diabetes presents with recurrent severe hypoglycemia despite reducing her insulin dose. Her insulin requirements have decreased by 40% over the past week. She reports decreased fetal movement. Fetal ultrasound shows intrauterine fetal demise. Evaluate the physiological mechanism explaining her changing insulin requirements in the context of pregnancy loss.

A 55-year-old man with type 1 diabetes for 30 years is hospitalized for pneumonia. Despite appropriate antibiotic therapy, his insulin requirements have tripled. Blood glucose ranges from 250-400 mg/dL. He develops hypotension unresponsive to fluid resuscitation. Cortisol level is 2 μg/dL (normal 5-25), and ACTH is 320 pg/mL (normal 10-60). Evaluate the endocrine complication and synthesize the pathophysiological connection to his primary disease.

A 42-year-old woman presents with tremor, anxiety, and weight loss. TSH is 0.02 mIU/L, free T4 is 3.2 ng/dL, and T3 is 280 ng/dL (normal 80-180). Radioactive iodine uptake scan shows uniformly increased uptake of 45% at 24 hours (normal 10-30%). Thyroid-stimulating immunoglobulin is positive. Analyze the feedback mechanism disruption occurring in this patient's hypothalamic-pituitary-thyroid axis.