Vahl N, Jørgensen J O, Jurik A G, Christiansen J S
Medical Department M (Endocrinology and Diabetes), Aarhus Kommunehospital, Aarhus University, Denmark.
J Clin Endocrinol Metab. 1996 Jun;81(6):2209-15. doi: 10.1210/jcem.81.6.8964853.
Growth hormone (GH) secretion is reduced with age in normal subjects. Aging is furthermore associated with a decline in lean body mass and an increase in relative adiposity, and overt obesity is a negative determinant of GH secretion in all age groups. We tested the hypothesis that differences in body composition and physical fitness rather than age determine stimulated GH secretion in healthy adults. Forty-two clinically nonobese adults [22 women and 20 men, mean age 39.4 yr (range 27-59), mean +/- SE body mass index (BMI) = 23.9 +/- 0.5 kg/m2] underwent 2 GH stimulation tests (arginine and clonidine), determination of maximal oxygen consumption (VO2-max), and a number of anthropometric measurements: body mass index (BMI), waist to hip (W/H)-ratio, intraabdominal fat and thigh muscle to fat (M/F)-ratio (computed tomography scan), total body fat, and lean body mass (DEXA scan). Peak GH levels were lower with clonidine [mean +/- SE (micrograms/L): 9.79 +/- 1.29 (arginine) vs. 3.56 +/- 0.57 (clonidine) (P < 0.001)]. Arginine-stimulated GH peak levels correlated negatively with indices of adiposity and age [intraabdominal fat: r = -0.72, P < 0.001; W/H-ratio: r = -0.58, P < 0.001; age: r = -0.54, P < 0.001], and positively with VO2-max [r = 0.60, P < 0.001]. Clonidine-stimulated GH peak correlated negatively with intraabdominal fat [r = -0.60, P < 0.001] and age [r = -0.46, P = 0.008]. Multiple linear regression revealed multicollinearity among several of the independent variables. In all equations abdominal adiposity and physical fitness, rather than age, contributed significantly to predict changes in arginine stimulated GH secretion. Intraabdominal fat was a more important determinant of the clonidine evoked GH response than age. In clinically nonobese, healthy adults relative adiposity, in particular in the abdominal region, is a major negative determinant of stimulated GH secretion, and physical fitness is an important positive predictor. The cause-effect relationship of these observations remains to be elucidated, but our findings may have clinical implications in the diagnosing of GH-deficiency in adults.
在正常受试者中，生长激素（GH）的分泌会随着年龄增长而减少。此外，衰老与瘦体重下降和相对肥胖增加有关，并且在所有年龄组中，明显肥胖都是GH分泌的负面决定因素。我们检验了这样一个假设：在健康成年人中，身体组成和体能的差异而非年龄决定了刺激后的GH分泌。42名临床非肥胖成年人[22名女性和20名男性，平均年龄39.4岁（范围27 - 59岁），平均±标准误体重指数（BMI）= 23.9±0.5 kg/m²]接受了2次GH刺激试验（精氨酸和可乐定）、最大耗氧量（VO2 - max）测定以及多项人体测量：体重指数（BMI）、腰臀比（W/H）、腹内脂肪和大腿肌肉与脂肪比（M/F）（计算机断层扫描）、全身脂肪和瘦体重（双能X线吸收法扫描）。可乐定刺激后的GH峰值较低[平均±标准误（微克/升）：精氨酸刺激后为9.79±1.29，可乐定刺激后为3.56±0.57（P < 0.001）]。精氨酸刺激后的GH峰值水平与肥胖指数和年龄呈负相关[腹内脂肪：r = - 0.72，P < 0.001；W/H比：r = - 0.58，P < 0.001；年龄：r = - 0.54，P < 0.001]，与VO2 - max呈正相关[r = 0.60，P < 0.001]。可乐定刺激后的GH峰值与腹内脂肪[r = - 0.60，P < 0.001]和年龄[r = - 0.46，P = 0.008]呈负相关。多元线性回归显示几个自变量之间存在多重共线性。在所有方程中，腹部肥胖和体能而非年龄对预测精氨酸刺激后的GH分泌变化有显著贡献。腹内脂肪是可乐定诱发的GH反应比年龄更重要的决定因素。在临床非肥胖的健康成年人中，相对肥胖，尤其是腹部肥胖，是刺激后GH分泌的主要负面决定因素，而体能是一个重要的正向预测指标。这些观察结果的因果关系仍有待阐明，但我们的发现可能对成人GH缺乏症的诊断具有临床意义。
