Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, PO Box 414, SE-405 30, Gothenburg, Sweden.
Environ Health. 2013 Mar 7;12:22. doi: 10.1186/1476-069X-12-22.
Cadmium (Cd) can cause renal damage and osteoporosis after high-level exposure. Recently such effects, including increased urinary excretion of calcium, have been shown also at low-level exposure, as measured by Cd in blood or urine. However, associations with kidney Cd have not been examined. The aim of this study was to explore the relation between kidney Cd and urinary calcium excretion, or bone mineral density.
Cd was determined in kidney cortex biopsies from 109 living kidney donors. Serum was analyzed for ionized calcium, parathyroid hormone and vitamin D. Calcium was analyzed in overnight and 24-hour urine samples. Bone mineral density was measured in a subgroup of 67 donors. Associations between single variables were assessed by Spearman and Pearson correlation coefficients. Differences between independent groups were compared using Student's t-test. For related samples, paired t-test was applied. Associations between urinary calcium and kidney Cd, ionized serum calcium, serum parathyroid hormone, inactive and active vitamin D and background variables were assessed using multiple linear regression and logistic regression.
In spite of relatively low kidney Cd levels (median 13 μg/g, range 1.5-55 μg/g) kidney Cd and urinary calcium were positively associated, mainly caused by an association in women. Donors with kidney Cd above the median (subgroup mean 23 μg/g) had significantly higher excretion of urinary calcium normalized for creatinine than those below the median (subgroup mean 7.3 μg/g). In women, also the excretion of Ca per hour was higher in those with high kidney Cd (24 hour sample mean 0.21 vs. 0.15 mmol/h; overnight sample 0.16 vs. 0.11 mmol/h). There were negative associations between kidney Cd and bone mineral density, most of which, however, disappeared in multivariate analyses.
This study provides support for an association between kidney Cd levels and urinary calcium excretion in women, but not in men. The results strengthen the case for preventive measures against Cd pollution.
镉（Cd）在高水平暴露后会导致肾脏损伤和骨质疏松。最近，研究表明，即使在低水平暴露下，也会出现类似的影响，如血液或尿液中的 Cd 含量增加。然而，目前尚未研究肾脏 Cd 与这些影响之间的关系。本研究旨在探讨肾脏 Cd 与尿钙排泄或骨密度之间的关系。
从 109 名活体肾捐献者的肾皮质活检组织中测定 Cd 含量。检测血清中的离子钙、甲状旁腺激素和维生素 D。分析 24 小时尿液和夜间尿液中的钙含量。对 67 名捐献者进行了骨密度检测。采用 Spearman 和 Pearson 相关系数评估单一变量之间的关系。使用 Student's t 检验比较独立组之间的差异。对于相关样本，应用配对 t 检验。采用多元线性回归和逻辑回归分析尿钙与肾脏 Cd、血清离子钙、血清甲状旁腺激素、无活性和活性维生素 D 以及背景变量之间的关系。
尽管肾脏 Cd 水平相对较低（中位数 13μg/g，范围 1.5-55μg/g），但肾脏 Cd 与尿钙呈正相关，主要是由于女性中的这种相关性。肾脏 Cd 高于中位数（亚组均值 23μg/g）的捐献者的尿钙排泄量经肌酐校正后明显高于中位数以下的捐献者（亚组均值 7.3μg/g）。在女性中，高肾脏 Cd 组的每小时尿钙排泄量也较高（24 小时样本均值 0.21 vs. 0.15mmol/h；夜间样本 0.16 vs. 0.11mmol/h）。肾脏 Cd 与骨密度呈负相关，但这些相关性在多变量分析中大部分消失。
本研究为女性肾脏 Cd 水平与尿钙排泄之间的关系提供了支持，但在男性中则没有。这些结果加强了对 Cd 污染预防措施的必要性。
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