The macimorelin-stimulated growth hormone test for adult growth hormone deficiency diagnosis.

Adult growth hormone deficiency (AGHD) causes a reduction in lean body mass, bone mineral density, exercise tolerance and overall quality of life and treatment with growth hormone (GH) improves some of these outcomes. Because symptoms are non-specific and random GH levels are not useful in establishing its diagnosis, provocative tests are often necessary. The insulin tolerance test is the 'gold standard' test for diagnosis of AGHD but it is often cumbersome to perform and is contraindicated in certain patients due to the risk of hypoglycemia. Administration of the orally available ghrelin mimetic and GH secretagogue macimorelin increases GH levels acutely via the ghrelin receptor GHSR1-a and it has been shown to have good sensitivity and specificity for diagnosing AGHD. Here we review the evidence of the potential use of macimorelin for this indication.