Selective use of the insulin tolerance test to diagnose hypopituitarism.

The insulin tolerance test is considered the gold standard for assessing the hypothalamic-pituitary-adrenal and growth hormone (GH) axes, but its use varies considerably among different endocrine units. We recommend using the insulin tolerance test to assess the hypothalamic-pituitary-adrenal axis within 3 months of pituitary surgery, where adrenocorticotropic hormone 1-24 testing is equivocal, and to assess for GH deficiency where the patient is being considered for GH replacement therapy. We also discuss safety issues, how to ensure adequate hypoglycaemia and possible alternative tests, such as the overnight metyrapone test and glucagon test.