NEET PG / USMLE – MCQ 48

A previously healthy 32-year-old woman who works as a nurse comes to the emergency department because of a 3-week history of episodes of dizziness, nausea, and profuse sweating that resolve with eating. She does not smoke. She drinks four glasses of wine weekly. Vital signs are within normal limits. Physical examination shows no abnormalities. While in the emergency department, she becomes dizzy and diaphoretic; and her serum glucose concentration is 45 mg/dL. Laboratory studies obtained during the episode show:
Serum
Glucose – 35 mg/dL
C peptide – 0.5 ng/mL (N=0.5–2.5)
Insulin – 20 μU/mL (N=5–20)
Cortisol – 10 μg/dL
Urine sulfonylurea – negative
Which of the following is the most likely site of a tumor in this patient?
A. Adrenal cortex
B. Adrenal medulla
C. Pancreas
D. Parathyroid gland
E. Pituitary gland
F. Thyroid gland

Correct answer : C. Pancreas

The patient has hypoglycemia due to insulinoma. Insulin:Glucose ratio more than 0.3 confirms the diagnosis. Pancreas is the site of insulinoma.