About 10% of patients with acromegaly (GH excess) have random GH serum level within the reference range. GH overproduction can be established by measuring GH response to a glucose load. The serum GH level in normal persons drop below 2.0 ng/mL after the oral administration of 100g of glucose.
Patients with GH excess fail to show this suppression and sometimes show a paradoxical increase in GH level. A load of 100g of glucose is given to the patient and serum GH levels are measured at baseline, 60, and 120 minutes after loading.