Savastano S, Di Somma C, Belfiore A, Guida B, Orio F, Rota F, Savanelli M C, Cascella T, Mentone A, Angrisani L, Lombardi G, Colao A
Division of Endocrinology, Department of Molecular and Clinical Endocrinology and Oncology, University Federico II, Naples, Italy.
J Endocrinol Invest. 2006 Jun;29(6):536-43. doi: 10.1007/BF03344144.
Morbidly obese subjects are characterized by multiple endocrine abnormalities and these are paralleled by unfavorable changes in body composition. In obese individuals, either 24-h spontaneous or stimulated GH secretion is impaired without an organic pituitary disease and the severity of the secretory defect is proportional to the degree of obesity. The GHRH+arginine (GHRH+ARG) test is likely to be the overall test of choice in clinical practice to differentiate GH deficiency (GHD) patients. Similarly to other provocative tests, GHRH+ARG is influenced by obesity per se. Therefore, a new cut-off limit of peak GH response of 4.2 microg/l in obese subjects has been recently assumed. The aim of the present study was to investigate the reciprocal influence between decreased GH secretion and body composition in a group of 110 morbidly obese subjects, using the new cut-off limit of peak GH response to GHRH+ARG test for these subjects. In our study, GHD was identified in 27.3% of the obese subjects, without gender difference. In GDH obese subjects body mass index (BMI), waist circumference, waist-to-hip ratio (WHR), fat mass (FM), and resistance (R) were higher while reactance (Xc), phase angle, body cell mass (BCM), IGF-I, or IGF-I z-scores were lower than in normal responders (p<0.001). In all obese subjects, GH peak levels showed a negative correlation with age, BMI, waist circumference and FM, and a positive correlation with IGF-I. In the stepwise multiple linear regression, waist circumference and FM were the major determinants of GH peak levels and IGF-I. In conclusion, using the new cut-off limit of peak GH response to GHRH+ARG test for obese subjects, about 1/3 morbidly obese subjects were GHD. GHD subjects showed a significantly different body composition compared with normal responders, and the secretory defect was correlated to different anthropometric variables with waist circumference and FM as the major determinants.
病态肥胖受试者具有多种内分泌异常，同时身体成分也发生了不利变化。在肥胖个体中，无论有无器质性垂体疾病，24小时自发性或刺激性生长激素（GH）分泌均受损，且分泌缺陷的严重程度与肥胖程度成正比。生长激素释放激素+精氨酸（GHRH+ARG）试验可能是临床实践中鉴别生长激素缺乏（GHD）患者的首选总体试验。与其他激发试验类似，GHRH+ARG本身也受肥胖影响。因此，最近设定了肥胖受试者GH峰值反应的新临界值为4.2μg/L。本研究的目的是利用针对这些受试者的GHRH+ARG试验的GH峰值反应新临界值，研究110名病态肥胖受试者中GH分泌减少与身体成分之间的相互影响。在我们的研究中，27.3%的肥胖受试者被诊断为GHD，无性别差异。与正常反应者相比，GHD肥胖受试者的体重指数（BMI）、腰围、腰臀比（WHR）、脂肪量（FM）和电阻（R）更高，而电抗（Xc）、相位角、身体细胞量（BCM）、胰岛素样生长因子-I（IGF-I）或IGF-I z评分更低（p<0.001）。在所有肥胖受试者中，GH峰值水平与年龄、BMI、腰围和FM呈负相关，与IGF-I呈正相关。在逐步多元线性回归中，腰围和FM是GH峰值水平和IGF-I的主要决定因素。总之，使用针对肥胖受试者的GHRH+ARG试验的GH峰值反应新临界值，约1/3的病态肥胖受试者为GHD。与正常反应者相比，GHD受试者的身体成分有显著差异，且分泌缺陷与不同的人体测量变量相关，其中腰围和FM是主要决定因素。
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