Endocrinology — MCQs

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.

A 35-year-old woman undergoes total thyroidectomy for papillary thyroid cancer. Two hours post-operatively, she develops perioral numbness and carpopedal spasm. Trousseau's sign is positive. Serum calcium is 6.8 mg/dL (normal 8.5-10.5). Analyze the pathophysiological mechanism linking the surgical procedure to her current presentation.

A 28-year-old woman with Addison's disease presents to the emergency department with severe vomiting and diarrhea for 2 days. She ran out of her medications 3 days ago. Blood pressure is 85/50 mmHg, heart rate 118/min. Laboratory results show sodium 128 mEq/L, potassium 6.2 mEq/L, glucose 65 mg/dL. Apply your understanding of adrenal physiology to determine the immediate hormonal deficiency causing her presentation.

Insulin is secreted along with which of the following molecules in a 1:1 molar ratio?