高磷血症与ESRD患者多个临床不良结局相关,如心血管疾病、血管钙化及死亡。研究显示,降低血磷可延缓钙化进展[1],降低死亡风险[2]。由于每周三次血液透析清除磷的效力有限,含铝磷结合剂的不良反应严重,含钙磷结合剂被大量用于透析患者进行血磷控制。但含钙磷结合剂真的适合ESRD患者吗?2014年美国学者Nishank Jain与Robert F. Reilly对这一问题进行了分析解答,该综述发表在Seminars in Dialysis[3]。
ESRD患者面临着较高的骨折风险,过去将这一风险被单纯的归因于患者机体处于负钙平衡。然而钙平衡的影响因素并不是单一的,如维生素D类似物也会影响钙平衡状态。为了了解碳酸钙是否会使慢性肾脏病(CKD)患者净骨钙量增加,2013年Hill KM等学者让8例CKD患者分别接受碳酸钙和安慰剂。该研究首次发现了碳酸钙会导致骨和软组织均出现正钙平衡,软组织中的正钙平衡可能会增加血管钙化发生风险[4]。
近年来多项研究报导了含钙磷结合剂的使用与血管钙化相关。2000年Goodman等发表的研究显示冠脉钙化的ESRD患者每天摄入的钙总量更高(P=0.02)[5],同年Guérin等发表的研究进一步证实了含钙磷结合剂的使用与血管钙化呈正相关,且剂量越高,钙化程度越严重(P=0.001)[6]。2008年London GM等的研究也证实,经多因素校正后,含钙磷结合剂的剂量与血管钙化程度独立相关(P<0.0001)[7]。因此,作者指出,目前对于CKD矿物质代谢异常的认识或许需要转变——不仅磷摄入过多会导致血管钙化,钙摄入过多也会导致血管钙化[8, 9]。
司维拉姆作为非含钙磷结合剂被大量报道可以改善透析患者临床转归,如心血管事件、全因死亡等[10-12]。2013年发表于The Lancet的一项荟萃分析也显示非含钙磷结合剂相比含钙磷结合剂可以降低CKD患者全因死亡风险达22%[13]。尽管由于现有研究存在结果不一致性、设计缺陷等问题,目前尚无法给出非含钙磷结合剂比含钙磷结合剂更好的定论,但是含钙磷结合剂带来的过多钙摄入却是值得担忧的。
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