单次及多次GHRH兴奋试验对鉴别下丘脑性和垂体性生长激素缺乏的价值评估

DIAGNOSIS OF HYPOTHALAMIC GROWTH HORMONE DEFICIENCY BY SINGLE OR MULTIPLE DOSES OF GROWTH HORMONE-RELEASING HORMONE

50例特发性生长激素缺乏症(IGHD)患者在一次静脉注射GHRH后,其中36％病例GH反应阳性(GH峰值≥5μg/L);用GHRH_(1-44)引发5日后,41％的GH反应阴性患者GH细胞转为有反应,使GH反应阳性率增至62％;继续用GHRH_(1-44)引发至10日未能再增加阳性反应率。结果提示,许多下丘脑性IGHD患者的垂体GH细胞,由于长期缺乏内源性GHRH兴奋,分泌功能低下,致对单次静脉注射GHRH无反应;但连续用外源性GHRH兴奋5日后,垂体GH细胞分泌功能逐渐恢复而有阳性反应。因此,5日GHRH兴奋试验对下丘脑性和垂体性IGHD已具有鉴别诊断意义。

This article reported the growth hormone (GH) responses, to single or multiple doses of GH-releasing hormone (GHRH1-41) in 50 patients of idiopathic GH deficiency (IGHD). After a single i.v. injection of 50μg GHRH1-44, the: serum GH level increased to ≥5μg/L in 36% of the patients. Priming with injection of 50μg GHRH1-44 daily for 5 days, the resting GH cells of the 41% of the negative responders were wakened and their serum GH peaks increased to ≥5μg/L on the 5th day after i.v. administration of GHRH1-44. Continuing the priming to 10 days did not increase the percentage of positive response significantly on the 10th day. Our results showed that the GH-secreting cell in most of the IGHD patients are resting due to the long-term lacking of endogenous GHRH, so that many of them could not respond to i.v.GHRH stimulation. After daily priming for 5 days, the GH-secreting cells restore their GH-secreting ability and are able to be responsivc to GHRH stimulation. Thus a 5-day GHRH stimulation test is helpful to distinguish the hypo- thalamic and pituitary IGHD and can be used to select those with hypothalamic IGHD for GHRH therapy.