Mallette L E, Kirkland J L, Gagel R F, Law W M, Heath H
Department of Internal Medicine, Baylor College of Medicine, Houston, Texas.
J Clin Endocrinol Metab. 1988 Nov;67(5):964-72. doi: 10.1210/jcem-67-5-964.
The synthetic amino-terminal fragment of PTH, PTH-(1-34), was recently released for clinical testing of PTH responsiveness. We measured the urinary cAMP and phosphaturic responses to infusion of PTH-(1-34) [3U/kg BW (200 U maximum), iv in 10 min] in patients with pseudohypoparathyroidism and idiopathic hypoparathyroidism, as well as normal subjects. The protocol used data from 5 30-min urine collections and 4 blood samples. Based on the results in 7 patients with pseudohypoparathyroidism (hypocalcemia with increased serum immunoreactive PTH concentrations), 2 patients with suspected pseudohypoparathyroidism, 9 patients with surgical hypoparathyroidism, and 10 normal subjects, this testing protocol differentiated well among these conditions. The patients with pseudohypoparathyroidism had blunted cAMP and phosphaturic responses to PTH-(1-34) administration compared to those of either normal or hypoparathyroid subjects. Induced hypercalcemia failed to restore a normal cAMP response to PTH-(1-34) infusion in 2 patients with pseudohypoparathyroidism. Calculation of the cAMP response to PTH-(1-34) as nanomoles per dL glomerular filtrate during the first 30 min after infusion provided better differentiation among groups than other parameters of cAMP metabolism. Calculating the phosphaturic response as the percent fall in tubular maximum for phosphate reabsorption during the first hour after infusion gave the best degree of statistical separation among groups. We conclude that this new diagnostic agent is effective for the study of renal responsiveness to PTH, and that the protocol described here reliably differentiates patients with pseudohypoparathyroidism from those with hypocalcemia due to other causes.
甲状旁腺激素（PTH）的合成氨基末端片段PTH-(1 - 34)最近已被批准用于甲状旁腺激素反应性的临床检测。我们测定了假性甲状旁腺功能减退症、特发性甲状旁腺功能减退症患者以及正常受试者对静脉输注PTH-(1 - 34) [3U/kg体重（最大200U），10分钟内输注完毕]后的尿cAMP和磷排泄反应。该方案采用了5次30分钟尿液收集数据和4份血样。基于7例假性甲状旁腺功能减退症患者（低钙血症伴血清免疫反应性甲状旁腺激素浓度升高）、2例疑似假性甲状旁腺功能减退症患者、9例手术性甲状旁腺功能减退症患者和10例正常受试者的结果，该检测方案能很好地区分这些情况。与正常或甲状旁腺功能减退的受试者相比，假性甲状旁腺功能减退症患者对PTH-(1 - 34)给药的cAMP和磷排泄反应减弱。2例假性甲状旁腺功能减退症患者中，诱导的高钙血症未能恢复对PTH-(1 - 34)输注的正常cAMP反应。输注后前30分钟内，以每分升肾小球滤过液中cAMP反应的纳摩尔数来计算对PTH-(1 - 34)的cAMP反应，比其他cAMP代谢参数能更好地区分组别。以输注后第一小时内磷酸盐重吸收最大管腔值下降的百分比来计算磷排泄反应，在各组间的统计学分离程度最佳。我们得出结论，这种新的诊断剂对研究肾脏对PTH的反应性有效，并且这里描述的方案能可靠地将假性甲状旁腺功能减退症患者与其他原因导致低钙血症的患者区分开来。
