ABSTRACTSalomon, F., Cuneo, R.C., Hesp, R. and Sönksen, P.H. (Department of Medicine, St. Thomas's Hospital, London, UK and the Radioisotopes Division, MRC Clinical Research Centre, Harrow, Middlesex, UK). Growth hormone deficiency in adults. Acta Paediatr Scand [Suppl] 356: 69, 1989.There is a lack of information on the long‐term effects of growth hormone (GH) treatment on body composition in adults with GH deficiency (GHD). In a randomized, double‐blind, placebo‐controlled study, the changes in body composition in 24 adults with severe GHD were investigated. The majority of patients had developed GHD in adulthood as a consequence of pituitary tumours and/or pituitary surgery. They were all receiving appropriate conventional pituitary replacement therapy (i.e. no GH) and had suffered from GHD for at least 12 months; the mean known duration of GHD was 8 years. Severe GHD was defined as peak GH levels of less than 3.0 mU/I in response to the insulin tolerance test. Treatment with recombinant human GH (rhGH, Genotropin' 0.07 IU/kg) or placebo was given for 6 months as a daily subcutaneous injection at bedtime. At entry into the study, lean body mass was reduced in the patients with GHD compared to normal controls, and total body fat was increased. Overall, there was no change in body weight in either group. However, lean body mass, as measured by total body potassium in a K40 counter, increased from 53.5 ± 0.6 (mean ± SEM) to 59.7 ± 0.6 kg over the Cmonth period in the GH‐treated group (p < 0.0001). The biggest increase occurred during the first month. No significant change was observed in the placebo group. In addition, an overall decrease in fat mass of 5.7 ± 0.9 kg was observed in the GH‐treated, but not the placebo‐treated, patients after 6 months, particularly on the abdominal site. Again the largest decrease occurred during the first month of treatment. The reduction in fat mass was also paralleled by a decrease in the total plasma cholesterol. GHD in adults has therefore been shown to be associated with an abnormal body composition. Replacement therapy with hGH for 6 months normalizes lean body mass (compared to predicted value) and reduces fat mass.