Adult-onset growth hormone deficiency (GHD) is a rare disease with an exact incidence that is not currently known, but indirect estimates based on the incidence of pituitary tumors suggest an incidence of 10 people per million annually (1). Over the last decade the adverse metabolic and psychological sequelae of adult GHD have been increasingly recognized, and the benefits of GH replacement demonstrated in randomized trials. These trials are limited to patients with severe GHD; thus the effects of GH replacement are most clearly established in patients with more severe GHD.