Growth hormone stimulation test: This test involves measuring growth hormone levels before and after the administration of a medication that stimulates growth hormone production. There are several types of growth hormone stimulation tests, but the most commonly used test is the arginine and insulin tolerance test (ITT) (2). During the arginine stimulation test, the patient is given an infusion of arginine, an amino acid that stimulates growth hormone release. Blood samples are taken before and after the infusion to measure growth hormone levels. During the ITT, the patient is given an injection of insulin to lower blood sugar levels, which stimulates growth hormone release. Blood samples are taken before and after the injection to measure growth hormone levels.

The Endocrine Society recommends the use of growth hormone stimulation tests to confirm the diagnosis of growth hormone deficiency in adults with low IGF-1 levels and clinical features suggestive of growth hormone deficiency (1). However, it is important to note that growth hormone stimulation tests can be expensive, time-consuming, and require close monitoring of the patient’s blood sugar levels, as the insulin injection used in the ITT can cause hypoglycemia in some patients.

References:

Molitch ME, Clemmons DR, Malozowski S, et al. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(6):1587-1609.

Vance ML. Diagnostic tests for adult GH deficiency. Pituitary. 2007;10(3):189-196.