Methylamine clearance by haemodialysis is low.
Methylamine clearance by haemodialysis is low.
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DOI：
10.1093/ndt/gfp629
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
M. Ponda;Zhe Quan;M. Melamed;A. Raff;T. Meyer;T. Hostetter
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文献类型：
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作者：
M. Ponda;Zhe Quan;M. Melamed;A. Raff;T. Meyer;T. Hostetter
透析充分性目前通过尿素清除率的测量来判断。然而，尿素是相对无毒的，并且具有不同于其他大类保留溶质的性质。特别是，细胞内螯合的溶质可能表现得与尿素不同。方法：我们研究了这一类的一个例子，脂肪胺单甲胺（MMA），在稳定的血液透析门诊患者（n = 10）使用基于HPLC的分析。结果终末期肾病患者透析前平均MMA水平为76 +/- 15 μ g/L，而正常人为32 +/- 4 μ g/L（n = 10）（P < 0.001）。平均尿素减少率为62%，而MMA减少率为43%（P < 0.01）。MMA水平在透析后1小时内反弹至基线的85%，而尿素水平仅反弹至基线的47%。与尿素相比，MMA具有更大的计算分布体积，与细胞内螯合一致。红细胞（RBC）内MMA浓度的测量结果证实，RBC中的MMA水平高于血浆中的MMA水平，比值为4.9：1。由于MMA的细胞内螯合，我们使用从全血中去除的量计算其清除率。尿素清除率平均为222 +/- 41 ml/min，MMA为121 +/- 14 ml/min，而肌酐血浆清除率为162 +/- 20 ml/min（所有差异均为P < 0.01）。使用体外透析，在不存在RBC的情况下，溶质清除率相似：尿素、肌酐和MMA分别为333 +/- 6、313 +/- 8和326 +/- 4 ml/min。这些结果表明，体内MMA清除率相对于肌酐较低是由于MMA移动到透析器血液路径内的RBC中，减少了透析对其的清除。结论总之，我们发现，在常规血液透析中，MMA的清除效率不如尿素或肌酐，并提高了红细胞可能限制其透析的可能性，不仅不能排出它，但进一步隔离它作为血液通过透析器。
BACKGROUND Dialysis adequacy is currently judged by measures of urea clearance. However, urea is relatively non-toxic and has properties distinct from large classes of other retained solutes. In particular, intracellularly sequestered solutes are likely to behave differently than urea. METHODS We studied an example of this class, the aliphatic amine monomethylamine (MMA), in stable haemodialysis outpatients (n = 10) using an HPLC-based assay. RESULTS Mean MMA levels pre-dialysis in end-stage renal disease subjects were 76 +/- 15 microg/L compared to 32 +/- 4 microg/L in normal subjects (n = 10) (P < 0.001). Mean urea reduction was 62% while the reduction ratio for MMA was 43% (P < 0.01). MMA levels rebounded in the 1 hour post-dialytic period to 85% of baseline, whereas urea levels rebounded only to 47% of baseline. MMA had a much larger calculated volume of distribution compared to urea, consistent with intracellular sequestration. Measures of intra-red blood cell (RBC) MMA concentrations confirmed greater levels in RBCs than in plasma with a ratio of 4.9:1. Because of the intracellular sequestration of MMA, we calculated its clearance using that amount removed from whole blood. Clearances for urea averaged 222 +/- 41 ml/min and for MMA 121 +/- 14 ml/min, while plasma clearance for creatinine was 162 +/- 20 ml/min (P < 0.01, for all differences). Using in vitro dialysis, in the absence of RBCs, solute clearance rates were similar: 333 +/- 6, 313 +/- 8 and 326 +/- 4 ml/min for urea, creatinine and MMA, respectively. These findings suggest that the lower MMA clearance relative to creatinine in vivo is a result of MMA movement into RBCs within the dialyser blood path diminishing its removal by dialysis. CONCLUSION In conclusion, we find that, in conventional haemodialysis, MMA is not cleared as efficiently as urea or creatinine and raise the possibility that RBCs may limit its dialysis not merely by failing to discharge it, but by further sequestering it as blood passes through the dialyser.