Adult growth hormone deficiency: current trends in diagnosis and dosing

Only approximately 20% of adults with GH deficiency (GHD) have a history of childhood-onset GHD; the remainder acquire GHD in adult life, usually through acquired damage to the pituitary-hypothalamic region. Diagnosis of GHD in adults is more difficult than in children and is made first from the clinical context, reinforced by signs and symptoms, and then confirmed by biochemical testing. The signs and symptoms, however, including altered body composition, reduced energy, and mild depression, are too common to have diagnostic value without a suggestive clinical context. Furthermore, biochemical tests for GH or IGF-I levels are imperfect, characterized by significant false-positive and -negative rates. GH dosing in adults has shifted to an individualized dose-titration approach, in which treatment is begun at a fixed dose and then titrated upward until IGF-I levels normalize, significant side effects develop, or beneficial effects plateau. Generally, women require higher GH doses than do men. Reflecting age-related differences in normal GH secretion, GH doses may be higher in young adults and lower in older patients.