Failure of insulin hypoglycemia to produce rise in serum prolactin.

Serum prolactin and growth hormone responses to insulin-induced hypoglycemia were measured in 5 normal individuals. While growth hormone rose appropriately in all subjects studied, serum prolactin levels did not significantly change despite the production of symptomatic hypoglycemia during testing. Prolactin response to insulin hypoglycemia is not a useful diagnostic test for prolactin secretion and cannot be used as such for assessment of pituitary reserve.