Fliser D, Franek E, Joest M, Block S, Mutschler E, Ritz E
Department of Internal Medicine, Ruperto-Carola University, Heidelberg, Germany.
Kidney Int. 1997 Apr;51(4):1196-204. doi: 10.1038/ki.1997.163.
In senescence renal function is thought to decline markedly even in the absence of renal disease. It has also been proposed that the changes in renal function with age are not uniform and that confounding factors such as hypertension or atherosclerosis may play a role. We performed a comprehensive study to compare several aspects of renal function in four groups: (i) young healthy normotensive subjects (N = 24; 13 males; mean age 26 +/- 3 years); (ii) elderly healthy normotensive subjects (elderly NT; N = 29; 13 males; 68 +/- 7 years); (iii) elderly treated and untreated hypertensive patients (elderly HT; N = 25; 13 males; 70 +/- 6 years); and (iv) elderly patients with compensated mild to moderate heart failure (elderly HF; N = 14; 6 males; 69 +/- 6 years). Compared to young subjects mean GFR (C(In)) and ERPF (C(PAH)) were significantly lower in the elderly, despite similar mean plasma creatinine levels (young, 121 +/- 11, 650 +/- 85 ml/min/1.73 m2; elderly NT, 103 +/- 11, 486 +/- 102; elderly HT, 103 +/- 13, 427 +/- 55; elderly HF, 92 +/- 14, 377 +/- 103). Nevertheless, GFR was within the normal range in the majority of elderly NT and HT, but not in elderly HF. ERPF was significantly lower in elderly HT as compared with elderly NT, and still lower in elderly HF. Mean renovascular resistance and filtration fraction were significantly higher in the elderly, particularly in elderly HT and HF as compared with the young. Mean fractional excretion of Na+ was similar in all groups studied, but the lithium clearance was significantly lower in the elderly, suggesting a greater proximal and less distal sodium reabsorption in senescence. In the elderly, mean PTH concentration and urinary excretion of pyridoline cross-links were significantly higher and mean 25-(OH)D3, calcitriol and phosphate concentrations significantly lower; the correlation between PTH and GFR was significant (r = -0.432, P < 0.001). The results document that the decrease in renal hemodynamics with senescence is less marked than suggested by some studies using less stringent methodology and inclusion criteria. Comorbid conditions confound renal function in the elderly. Age-associated changes in renal hemodynamics are accompanied by significant alterations of renal hormones and of renal sodium handling.
在衰老过程中，即使没有肾脏疾病，肾功能也被认为会显著下降。也有人提出，肾功能随年龄的变化并不一致，高血压或动脉粥样硬化等混杂因素可能起作用。我们进行了一项综合研究，比较了四组人群肾功能的几个方面：（i）年轻健康的血压正常受试者（N = 24；13名男性；平均年龄26±3岁）；（ii）老年健康的血压正常受试者（老年血压正常组；N = 29；13名男性；68±7岁）；（iii）老年接受治疗和未接受治疗的高血压患者（老年高血压组；N = 25；13名男性；70±6岁）；以及（iv）代偿性轻度至中度心力衰竭的老年患者（老年心力衰竭组；N = 14；6名男性；69±6岁）。与年轻受试者相比，老年受试者的平均肾小球滤过率（C(In)）和有效肾血浆流量（C(PAH)）显著降低，尽管平均血浆肌酐水平相似（年轻组，121±11，650±85 ml/min/1.73 m2；老年血压正常组，103±11，486±102；老年高血压组，103±13，427±55；老年心力衰竭组，92±14，377±103）。然而，大多数老年血压正常组和老年高血压组的肾小球滤过率在正常范围内，但老年心力衰竭组则不然。与老年血压正常组相比，老年高血压组的有效肾血浆流量显著降低，老年心力衰竭组更低。老年受试者的平均肾血管阻力和滤过分数显著更高，尤其是与年轻受试者相比，老年高血压组和老年心力衰竭组更高。所有研究组的平均钠分数排泄相似，但老年人的锂清除率显著降低，表明衰老过程中近端钠重吸收增加，远端钠重吸收减少。在老年人中，平均甲状旁腺激素浓度和吡啶交联物的尿排泄显著更高，而平均25-(OH)D3、骨化三醇和磷酸盐浓度显著更低；甲状旁腺激素与肾小球滤过率之间的相关性显著（r = -0.432，P < 0.001）。结果表明，衰老过程中肾血流动力学的下降不如一些使用不太严格方法和纳入标准的研究所表明的那样明显。合并症会混淆老年人的肾功能。与年龄相关的肾血流动力学变化伴随着肾激素和肾钠处理的显著改变。
