Naafs M A, Fischer H R, Koorevaar G, Hackeng W H, Schopman W, Silberbusch J
Department of Medicine, Municipal Hospital Bergweg, Rotterdam, The Netherlands.
Calcif Tissue Int. 1987 Nov;41(5):262-6. doi: 10.1007/BF02555227.
The renal responses to PTH infusion were compared in two age groups of healthy subjects. Basal nephrogenous cyclic AMP (NcAMP) was higher (1.68 +/- 0.74 vs. 0.97 +/- 0.50 nmol/dl GF; P less than 0.05) and TmPO4/GFR was lower (0.93 +/- 0.21 vs. 1.16 +/- 0.14 mmol/liter; P less than 0.025) in 10 elderly subjects compared with 12 young adults. Creatinine clearance was decreased in the elderly (84.8 +/- 25.7 vs. 144.7 +/- 43.2 ml/min; P less than 0.005) and serum iPTH tended to be increased (0.15 +/- 0.11 vs. 0.11 +/- 0.03 pmol/liter). Following the infusion of 3 IU bPTH/kg bodyweight, no significant differences in delta NcAMP and delta TmPO4/GFR were seen between the groups. When responses were expressed as percentual change of basal level, elderly subjects showed a % NcAMP of 1831 +/- 1200 which was comparable with 2038 +/- 1503% in young adults. However, the percentual change in TmPO4/GFR was significantly higher in elderly persons (24.2 +/- 11.9 vs. 11.9 +/- 8.0%; P less than 0.01). In young subjects, virtually absent TmPO4/GFR responses were found in 3 cases with a relatively low basal TmPO4/GFR (between 0.92 and 0.98 mmol/liter), but these cases showed normal increases in NcAMP. Elderly subjects retained a considerable delta TmPO4/GFR notwithstanding a basal TmPO4/GFR below 0.92 in seven out of 10 cases. These results confirm the existence of a slight increase in parathyroid activity in the elderly. In addition, they suggest an augmented sensitivity of the renal tubule concerning PO4 reabsorption in elderly subjects. It is speculated that this phenomenon is related to the fall in bone mineral retention in senescence and might reflect a defense mechanism against phosphate overload.
在两个年龄组的健康受试者中比较了对甲状旁腺激素（PTH）输注的肾脏反应。与12名年轻成年人相比，10名老年受试者的基础肾源性环磷酸腺苷（NcAMP）较高（1.68±0.74对0.97±0.50 nmol/dl肾小球滤过液；P<0.05），而TmPO4/GFR较低（0.93±0.21对1.16±0.14 mmol/升；P<0.025）。老年受试者的肌酐清除率降低（84.8±25.7对144.7±43.2 ml/分钟；P<0.005），血清iPTH有升高趋势（0.15±0.11对0.11±0.03 pmol/升）。在输注3 IU bPTH/千克体重后，两组之间的ΔNcAMP和ΔTmPO4/GFR没有显著差异。当反应以基础水平的百分比变化表示时，老年受试者的NcAMP百分比为1831±1200，与年轻成年人的2038±1503%相当。然而，老年受试者中TmPO4/GFR的百分比变化显著更高（24.2±11.9对11.9±8.0%；P<0.01）。在年轻受试者中，3例基础TmPO4/GFR相对较低（在0.92至0.98 mmol/升之间）的病例几乎没有TmPO4/GFR反应，但这些病例的NcAMP有正常升高。10例中有7例老年受试者的基础TmPO4/GFR低于0.92，但仍有相当大的ΔTmPO4/GFR。这些结果证实了老年人甲状旁腺活性略有增加。此外，它们表明老年受试者肾小管对磷酸盐重吸收的敏感性增强。据推测，这种现象与衰老过程中骨矿物质保留的下降有关，可能反映了一种针对磷酸盐过载的防御机制。
