C. Serum gastrin ?
C. Serum gastrin ?A routine physical examination demonstrates hypercalcemia in a 40-year-old man. Circulatory levels of parathyroid hormone are also elevated. Exploratory surgery of the neck reveals diffuse hyperplasia of all four parathyroid glands. Which of the following screening studies would most likely be helpful in confirming the diagnosis of multiple endocrine neoplasia, type I (MEN I)?
A. Pentagastrin-simulated calcitonin secretion
B. Serum epinephrine
C. Serum gastrin
D. Serum norepinephrine
E. Urinary adrenaline:noradrenaline ratio