ABDOMINAL ADIPOSITY RATHER THAN AGE AND SEX PREDICTS MASS AND REGULARITY OF GH SECRETION IN HEALTHY-ADULTS

We tested the hypothesis that body composition is the major predictor of growth hormone (GH) secretion in nonobese adults. We measured lean and fat tissue distribution (computerized tomography and dual-energy X -ray absorptiometry scan) and physical fitness [maximal oxygen consump tion ((V) over dotO(2max))] in 42 healthy nonobese adults (22 women an d 20 men, age range 27-59 yr, mean +/- SE body mass index = 24 +/- 0.5 kg/m(2)). Deconvolution analysis was used to estimate specific featur es of 24-h GH secretion and clearance. Approximate entropy was used to quantify the regularity of GH release. Older subjects exhibited decre ased estimates of GH secretion compared with younger subjects. Females had higher estimates of GH secretion, a longer GH half-life, and disp layed more irregularity in GH release than males. Mean 24-h serum GH c oncentrations correlated inversely with intra-abdominal fat and waist- to-hip ratio and positively with (V) over dotO(2max). Multiple linear regression analysis revealed intraabdominal fat as the dominant determ inant of estimates of GH secretion. (V) over dotO(2max) was more impor tant than sex and age in predicting GH secretion. We conclude that abd ominal fat is the major determinant of GH secretion in healthy nonobes e adults. Although the underlying mechanisms remain elusive, our findi ngs extend the clinical implications of visceral adiposity to include hyposomatotropism.