Mardini Joëlle, Lavergne Valery, Ghannoum Marc
Nephrology Department, Verdun Hospital, University of Montreal, 4000 Lasalle Blvd, Montreal, QC, Canada.
Int Urol Nephrol. 2014 Jul;46(7):1361-5. doi: 10.1007/s11255-014-0752-8. Epub 2014 Jun 18.
Dialysis-dependent patients are particularly susceptible to the toxic effects of aluminum (Al) because of their impaired ability to eliminate it. Al contamination of dialysis fluid remains a threat in this population. The mechanism for Al diffusion across dialysis membranes is not well established. Our objective is to verify, in AL-exposed patients, the postulate that the direction of Al transfer is predicted by the concentration gradient between free diffusible plasma Al and dialysate Al.
A systematic review of the literature was performed. Only papers which included Al plasma concentration ([Al]p), Al dialysate concentration ([Al]d) and direction of Al transfer (positive = from dialysate to plasma, negative = from plasma to dialysate) were selected. We also included four patients from our own cohort. Assuming that [Al]p has an ultrafiltrable fraction between 17 and 23%, cases were considered in keeping with our hypothesis if any of the following scenarios was present: negative Al transfer when [Al]d < [Al]p23% and positive Al transfer when [Al]d > [Al]p17%.
The search yielded 409 articles, of which 12 were selected for review. When reviewing individual patients for analysis, 108 out of 115 (94%) patients followed our hypothesis. By further excluding cases in which Al transfer could not be determined, only three out of 111 patients were contrary to out hypothesis.
Comparing ultrafiltrable Al to dialysate Al permits to accurately predict the direction of Al transfer. The optimal [Al]d should be <20% of the maximally acceptable [Al]p. In order to follow K/DOQI guidelines ([Al]p < 20 μg/L), the [Al]d should therefore not exceed 4 μg/L. At the level presently supported by K/DOQI ([Al]d < 10 μg/L), [Al]p could realistically reach 50 μg/L and potentially cause toxicity.
依赖透析的患者因其清除铝（Al）的能力受损，对铝的毒性作用尤为敏感。透析液中的铝污染对这一人群仍然构成威胁。铝跨透析膜扩散的机制尚未完全明确。我们的目的是在铝暴露患者中验证以下假设：铝的转移方向由游离可扩散血浆铝和透析液铝之间的浓度梯度预测。
对文献进行系统回顾。仅选择包含血浆铝浓度（[Al]p）、透析液铝浓度（[Al]d）和铝转移方向（正向 = 从透析液到血浆，负向 = 从血浆到透析液）的论文。我们还纳入了来自我们自己队列的4名患者。假设[Al]p的超滤部分在17%至23%之间，如果出现以下任何一种情况，则认为病例符合我们的假设：当[Al]d < [Al]p * 23%时铝转移为负向，当[Al]d > [Al]p * 17%时铝转移为正向。
检索得到409篇文章，其中12篇被选作综述。在审查个体患者进行分析时，115名患者中有108名（94%）符合我们的假设。通过进一步排除无法确定铝转移的病例，111名患者中只有3名与我们的假设相反。
将超滤铝与透析液铝进行比较可以准确预测铝的转移方向。最佳的[Al]d应小于最大可接受的[Al]p的20%。为了遵循K/DOQI指南（[Al]p < 20 μg/L），因此[Al]d不应超过4 μg/L。在目前K/DOQI支持的水平（[Al]d < 10 μg/L）下，[Al]p实际可能达到50 μg/L并可能导致毒性。
