Related Experiment Video
Updated: Aug 12, 2026

Characterization of Metabolic Status in Nonhuman Primates with the Intravenous Glucose Tolerance Test
Published on: November 13, 2016
Evaluation of treated acromegalic patients with normal growth hormone levels during oral glucose load
Abstract:
Twenty-one treated acromegalics with plasma GH levels less than or equal to 5 ng/ml were evaluated during an oral glucose tolerance test (OGTT). Serum insulin-like growth factor (IGF) levels, measured by a competitive binding assay, were high in 10, normal in 8 and low in 3 patients. Urinary calcium excretion (Ca U), measured over 24 h, was elevated in 9 of the 10 patients whose IGF levels were high, whereas only 1 of the patients with normal or low IGF levels was hypercalciuric. A paradoxical rise in GH following TRH injection was observed in 5 of the 10 patients whose IGF levels were high, whereas all patients with normal or low IGF levels showed no GH response to TRH. GH levels greater than or equal to 10 ng/ml occurred during ornithine (ORN) administration in 6 of the 18 patients with normal or high IGF levels. The remaining 12 patients with no GH rise during ORN included 2 cases in which IGF levels were high and GH rose following TRH, and 2 cases in which IGF levels were normal and GH levels were greater than or equal to 10 ng/ml during insulin-induced hypoglycaemia (IIH), thus excluding a GH deficiency. These results show that acromegaly is not cured in certain treated patients with normal GH levels during OGTT. It seems that IGF and Ca U determinations are valuable indices of activity, in contrast to GH response to ORN. The GH response to TRH is also relatively useful.
More Related Videos
07:43Endoscopic Endonasal Trans-sphenoidal Approach: Minimally Invasive Surgery for Pituitary Adenomas
Published on: January 17, 2018
08:13Study of In Vivo Glucose Metabolism in High-fat Diet-fed Mice Using Oral Glucose Tolerance Test (OGTT) and Insulin Tolerance Test (ITT)
Published on: January 7, 2018
Related Concept Videos
Hormones Regulating Blood Glucose
In addition to accelerating glucose uptake and utilization, insulin has...
Insulin: Dosing Regimen and Adverse Effects
The basal dose constitutes about 40%-50% of the total daily dose, with the rest as premeal insulin. The mealtime insulin dose should mirror...
Oral Hypoglycemic Agents: α-Glucosidase Inhibitors
Acarbose and miglitol are typically...
Glucagon-like Receptor Agonists
GLP-1, when administered in high doses intravenously, triggers insulin secretion, inhibits glucagon release, slows gastric emptying, reduces food intake, and restores normal insulin secretion. However, its rapid inactivation by the...
Hypoglycemia and Glucagon
Hyperglycemia