The oral glucose tolerance test is used for the diagnosis of acromegaly and to determine the status of remission after pituitary surgery. In normal individuals, hyperglycemia suppresses growth hormone secretion.
NPO for at least 8 hours prior to suppression test.
1. Baseline serum growth hormone, somatomedin-C and glucose levels
2. Administer 100 g of glucola orally over 5 minutes
3. Serum glucose and growth hormone levels at 30, 60, 90 and 120 minutes
In normal individuals, growth hormone suppresses below 2 ng/ml after ingesting 100 g of glucola. More sensitive assays require a growth hormone level below 1 ng/ml to rule out acromegaly. False positive results can occur in patients with diabetes mellitus. anorexia, liver failure, tall adolescents, and individuals with growth hormone resistance disorders.