Diagnosis of severe growth hormone (GH) deficiency in young adults who received GH replacement therapy during childhood

Between 20% and 87% of young adults who had completed growth hormone (GH) therapy in childhood for a putative diagnosis of GH deficiency (GHD) had normal GH responses to provocative tests when they were retested. Patients with isolated idiopathic GHD were more likely to exhibit normal GH responses at retest in young adult life than were patients with multiple pituitary hormone deficits. When determining which patients should receive GH therapy in adult life, those who have isolated GHD should undergo two tests of GH status, while those with multiple anterior pituitary hormone deficits require only one test. Most information is available for the insulin tolerance test, the arginine stimulation test and the glucagon stimulation test, but more recent methods, such as GH-releasing hormone in combination with pyridostigmine, are showing promise in the investigation of GHD. In young adults with childhood-onset GHD, the serum concentration of insulin-like growth factor I is a useful marker of GH status, and can be used in conjunction with a GH provocative test. The choice of GH provocative test should ultimately depend on the experience and policy developed at the centre performing the assessment. Whichever tests are chosen, each should be validated in subjects known to have hypothalamic-pituitary disease as well as in normal individuals.