BODY-COMPOSITION IN GROWTH-HORMONE DEFICIENT ADULTS OVER THE AGE OF 60 YEARS

OBJECTIVE Elderly patients with hypothalamic-pituitary disease exhibit a reduction in GH secretion distinct from the decline in GH secretion related to age, GH deficiency in young adults causes a change in body composition, with increased fat mass (FM) and reduced fat free mass ( FFM), similar to that seen as a result of the normal ageing process. T he aim of this study was to determine whether organic GH deficiency in elderly patients may cause changes in body composition beyond those d ue to ageing. SUBJECTS Twenty-one patients (15 male) with documented p ituitary disease and 24 controls (17 male) matched for age, height, we ight and BMI, all over the age of 60, in whom GH status had been defin ed by a 24-hour GH profile and an arginine stimulation test. MEASUREME NTS Serum was taken for fasting IGF-I and IGFBP-1 estimations. Total a nd regional FM and FFM were determined using dual-energy X-ray absorpt iometry. RESULTS FM (median (range)) was increased in the patients, 27 .76 (19.25-50.24) vs 21.23 (8.81-49.15) kg in the controls (P < 0.005) . FM was significantly increased in the arms, legs and trunk in the pa tients compared with the controls. The proportion of fat deposited cen trally did not differ significantly between the two groups (57.0% (47. 6-65. 1) in the patients vs 55.3% (44.1-63.8) in the controls, P = 0.2 5). There was an inverse relation between total FM and serum IGFBP-1 p resent in the patients, rho=-0.632, P < 0.005, and in the controls rho =-0.467, P < 0.05, but the relation between total FM and area under th e On profile was significant only in the controls (rho=-0.651, P < 0.0 01) and not in the patients. FFM (51.19 (26.96-69.18) kg in the patien ts vs 51.55 (32.35-60.53) kg in the controls, P=0.99) and serum IGFBP- 1 levels did not differ significantly between the two groups. CONCLUSI ON Organic growth hormone deficiency causes changes in body compositio n beyond the changes associated with the ageing process. These changes differ from those seen in younger On deficient adults in that they ar e limited to an increase in FM with no change in FFM. These findings i ndicate that even in the elderly, in whom On secretion is normally ver y tow, the additional imposition of GH deficiency due to organic disea se has significant biological impact.