Hussain K, Hindmarsh P, Aynsley-Green A
London Center for Pediatric Endocrinology and Metabolism, Great Ormond Street Hospital for Children, National Health Service Trust, London WC1N 3JH, United Kingdom.
J Clin Endocrinol Metab. 2003 Aug;88(8):3715-23. doi: 10.1210/jc.2003-030137.
Hypoglycemia is a potent stimulus for GH and cortisol secretion. The insulin tolerance test (ITT) is the gold standard for assessing GH and cortisol responses from the hypothalamic-pituitary-adrenal axis. The serum GH and cortisol responses to spontaneous hypoglycemia in 22 children were compared with those of 16 children undergoing an ITT for diagnostic purposes. The mean serum GH and cortisol concentrations 1 h before spontaneous hypoglycemia were 6.9 +/- 1.1 mU/liter and 424 +/- 51 nmol/liter, respectively, and at the time of spontaneous hypoglycemia they were 6.7 +/- 1.3 mU/liter and 601 +/- 66 nmol/liter, respectively. The mean serum GH and cortisol values at +10, +20, +30, +40, and +50 min from the time of hypoglycemia were 5.4 +/- 1.0, 4.7 +/- 0.7, 4.6 +/- 1.0, 5.4 +/- 1.4, and 5.5 +/- 1.3 mU/liter and 633 +/- 69, 645 +/- 71, 668 +/- 70, 680 +/- 72, and 662 +/- 77 nmol/liter, respectively. There was no significant difference between any of these means for GH secretion. In contrast, in the ITT the mean serum GH concentration before hypoglycemia was 5.1 +/- 1.3 mU/liter, and at the time of hypoglycemia it was 29.2 +/- 7.30 mU/liter. The difference between these means was highly significant (P < 0.01, by t test). There was no significant difference between the cortisol response to spontaneous hypoglycemia and that to the ITT. Physiological changes in the serum nonesterified fatty acid concentration had no significant effect on serum GH secretion. In conclusion, the mechanism(s) of the serum GH response to spontaneous hypoglycemia is different from that due to the ITT. A low GH level detected at the time of spontaneous hypoglycemia does not necessarily imply GH deficiency or GH as a cause of the hypoglycemia.
低血糖是生长激素（GH）和皮质醇分泌的有力刺激因素。胰岛素耐量试验（ITT）是评估下丘脑 - 垂体 - 肾上腺轴对GH和皮质醇反应的金标准。将22名儿童自发性低血糖时的血清GH和皮质醇反应与16名因诊断目的接受ITT的儿童的反应进行了比较。自发性低血糖前1小时血清GH和皮质醇的平均浓度分别为6.9±1.1 mU/升和424±51 nmol/升，在自发性低血糖时分别为6.7±1.3 mU/升和601±66 nmol/升。低血糖发生后10、20、30、40和50分钟时血清GH和皮质醇的平均数值分别为5.4±1.0、4.7±0.7、4.6±1.0、5.4±1.4和5.5±1.3 mU/升以及633±69、645±71、668±70、680±72和662±77 nmol/升。这些GH分泌平均值之间无显著差异。相比之下，在ITT中，低血糖前血清GH平均浓度为5.1±1.3 mU/升，低血糖时为29.2±7.30 mU/升。这些平均值之间的差异非常显著（经t检验，P<0.01）。自发性低血糖与ITT时皮质醇反应之间无显著差异。血清非酯化脂肪酸浓度的生理变化对血清GH分泌无显著影响。总之，血清GH对自发性低血糖的反应机制与ITT引起的不同。自发性低血糖时检测到的低GH水平不一定意味着GH缺乏或GH是低血糖的原因。
