Ritz E, Seidel A, Ramisch H, Szabo A, Bouillon R
Department of Internal Medicine, University of Heidelberg, FRG.
Nephron. 1991;57(3):314-8. doi: 10.1159/000186281.
Despite elevated parathyroid hormone (PTH) levels, low normal or diminished serum 1,25(OH)2D3 concentrations are found in patients with incipient renal failure. To further assess (indirectly) the reserve capacity of renal production of 1,25(OH)2D3 we studied 9 patients with incipient or moderate renal failure (inulin clearance 31-68ml/min/1.73 m2) and 9 controls, using a novel stimulation test. We measured 1,25 (OH)2D3 levels, free 1,25(OH)2D3 index, cAMP excretion, calciuria and phosphaturia before and after infusion of 2 x 400 U of human (h) PTH (1-38). Baseline 1,25(OH)2D3 levels were not significantly different in patients (42.5 pg/ml, 21.6-51.1) compared with controls (45.0 pg/ml, 37.4-67.3). After infusion of hPTH(1-38), however, median increase in 1,25(OH)2D3 was only +25% versus +86% in controls, despite a greater proportional increase in cAMP/GF ratio. The data suggest subnormal stimulation of renal 1,25(OH)2D3 production in response to exogenous PTH in most patients with incipient renal failure. This may reflect partial exhaustion of biosynthetic reserve capacity.
尽管甲状旁腺激素（PTH）水平升高，但在早期肾衰竭患者中仍发现血清1,25(OH)₂D₃浓度处于低正常或降低水平。为了进一步（间接）评估肾脏产生1,25(OH)₂D₃的储备能力，我们使用一种新型刺激试验研究了9例早期或中度肾衰竭患者（菊粉清除率为31 - 68ml/min/1.73 m²）和9例对照者。我们在输注2×400 U人（h）PTH（1 - 38）前后测量了1,25(OH)₂D₃水平、游离1,25(OH)₂D₃指数、cAMP排泄、尿钙和尿磷。患者的基线1,25(OH)₂D₃水平（42.5 pg/ml，21.6 - 51.1）与对照者（45.0 pg/ml，37.4 - 67.3）相比无显著差异。然而，输注hPTH(1 - 38)后，1,25(OH)₂D₃的中位数增加仅为+25%，而对照者为+86%，尽管cAMP/GF比值的增加比例更大。数据表明，大多数早期肾衰竭患者对外源性PTH的反应中，肾脏1,25(OH)₂D₃产生的刺激低于正常水平。这可能反映了生物合成储备能力的部分耗尽。
