The main goal of growth hormone (GH)-replacement therapy for adults with growth hormone deficiency is to achieve physiologic re' placement. GH secretion varies from day to day and depends on a number of factors including age, sex, body composition, and sleep patterns. This variability means that GH dosage must be individualized and adjusted in response to efficacy and safety outcomes. The efficacy of GH-replacement therapy can be monitored by assessing changes in body composition or in levels of GH-related peptides. In addition, patients should be monitored for the occurrence of adverse events.