Beneficial effects of growth hormone replacement in growth hormone-deficient adults

Adult growth hormone deficiency (AGHD) is associated with a reduction in lean body and muscle mass, an increased risk for cardiovascular morbidity and mortality, reduced muscle strength and impaired physical fitness, and decreased bone mass. These physical changes are often accompanied by impairment in psychological well-being. Growth hormone (GH) replacement therapy has proven to be beneficial in increasing lean body and muscle mass. Importantly, GH replacement therapy has significant positive effects on lipid profiles and central adiposity, two major cardiovascular risk factors. Improvements in bone mineral density are also often seen with replacement therapy. The diagnosis of AGHD should be considered in adults with a history of a mass lesion in the sella or hypothalamus, cranial irradiation, or documented childhood-onset GH deficiency. Adults with a history of head trauma should also be considered for this diagnosis. The traditional provocative test used for the diagnosis is the insulin tolerance test (ITT). However, the complexity and inherent risks associated with the ITT have resulted in many clinicians using arginine alone or in combination with GH-releasing hormone as the provocative test of choice. Growth hormone therapy should be individualized, with dose adjustments based on clinical and biochemical response. Serum insulin,like growth factor I concentrations are used to evaluate the effectiveness of therapy, with the goal of therapy to return these levels to the upper one-half of the normal age adjusted and sex-adjusted normal ranges. Adverse effects of GH replacement therapy are minor and are minimized by individualizing therapy based on clinical response.