Prince R L, Hutchison B G, Kent J C, Kent G N, Retallack R W
University Department of Medicine, University of Western Australia.
Kidney Int. 1988 Mar;33(3):722-8. doi: 10.1038/ki.1988.58.
Serum calcitriol and the free calcitriol index together with factors considered to regulate calcitriol production were measured in eleven patients with moderate chronic renal failure (MCRF) and eleven age- and sex-matched normal subjects. Although the serum dialysable calcium levels were similar in the two groups, there was depression of calcitriol levels and an elevation of PTH and nephrogenous cyclic AMP (NcAMP) levels in the MCRF patients. Furthermore, plasma phosphate levels were higher and the renal phosphate threshold was depressed in this patient group. When all subjects were grouped together calcitriol was positively correlated with GFR. When calcitriol levels were factored for GFR, to permit an assessment of calcitriol production per unit functioning renal mass, there was no significant difference between normal and MCRF subjects. To determine whether reserve for calcitriol production existed, six of the MCRF patients and six of the age- and sex-matched normal subjects received a low calcium diet for one week supplemented by cellulose phosphate to bind calcium within the gut. In both groups there was a significant rise in calcitriol, although the absolute levels were much lower in the MCRF patients than the normal subjects. These results suggest that calcitriol deficiency is a major feature of MCRF despite marked hyperparathyroidism. The rise in calcitriol levels in MCRF suggests persistent reserve secretory capacity in this condition. Therefore, the low serum calcitriol concentration may be due not only to structural renal damage, but also to suppression of calcitriol formation perhaps due to altered renal phosphate handling.
对11例中度慢性肾衰竭（MCRF）患者和11例年龄及性别匹配的正常受试者测定了血清骨化三醇、游离骨化三醇指数以及被认为可调节骨化三醇产生的相关因素。尽管两组患者的血清可透析钙水平相似，但MCRF患者的骨化三醇水平降低，甲状旁腺激素（PTH）和肾源性环磷酸腺苷（NcAMP）水平升高。此外，该患者组的血浆磷酸盐水平较高，肾磷酸盐阈值降低。当将所有受试者归为一组时，骨化三醇与肾小球滤过率（GFR）呈正相关。当对骨化三醇水平进行GFR校正，以评估每单位功能性肾组织的骨化三醇产生情况时，正常受试者与MCRF患者之间无显著差异。为了确定是否存在骨化三醇产生储备，6例MCRF患者和6例年龄及性别匹配的正常受试者接受了为期一周的低钙饮食，并补充纤维素磷酸盐以在肠道内结合钙。两组患者的骨化三醇均显著升高，尽管MCRF患者的绝对水平远低于正常受试者。这些结果表明，尽管存在明显的甲状旁腺功能亢进，但骨化三醇缺乏仍是MCRF的主要特征。MCRF患者骨化三醇水平的升高表明在此情况下存在持续的储备分泌能力。因此，血清骨化三醇浓度低可能不仅是由于肾脏结构损伤，还可能是由于肾脏磷酸盐处理改变导致骨化三醇形成受到抑制。
