Department of Chemistry, University of California, Irvine, California 92697, USA.
J Ren Nutr. 2012 May;22(3):357-64. doi: 10.1053/j.jrn.2011.07.003. Epub 2011 Nov 18.
End-stage renal disease (ESRD) causes accumulation of nitrogenous waste products and acid-base, mineral, fluid, and electrolyte disorders, which are partially corrected by hemodialysis (HD). While the effects of ESRD and dialysis on body fluid composition are well known, the effects on composition of expired breath are uncertain. Methanol is produced from unabsorbable complex carbohydrates by the colonic microbiome. Dietary restrictions of fruits and vegetables aimed at limiting potassium intake lower the intake of dietary fibers; the reduced fiber intake can in turn reduce production of methanol and its appearance in the exhaled breath. In this study, we investigated the inter- and intradialytic changes in the breath methanol levels.
Ten ESRD patients were studied during HD procedures at 3- and 2-day interdialytic intervals. On each occasion, 20 exhaled breath and room air samples were collected using evacuated canisters. Ten age-matched normal subjects served as controls. The samples were analyzed on a unique 6-column/detector gas chromatography system.
Seven ESRD patients consuming renal diet had lower methanol concentration (90 ± 29 ppbv) than the 3 patients consuming high-fiber diet (340 ± 48 ppbv, P ≤ .0006) and the 10 controls consuming unrestricted diets (202 ± 80 ppbv, P ≤ .001). HD significantly lowered breath methanol (60% ± 12%), paralleling the fall in serum urea concentration (70% ± 6%). The predialysis methanol concentration was slightly higher at 3-day than the 2-day interdialytic intervals.
Dietary restriction of fruits and vegetables lowers methanol production by the gut microbial flora in ESRD patients. Perhaps, methanol is a reliable breath biomarker to monitor individuals' daily fiber intake. Breath methanol is dramatically reduced by HD, reflecting its efficient removal.
终末期肾病（ESRD）会导致含氮废物和酸碱、矿物质、体液及电解质紊乱，这些问题可以通过血液透析（HD）部分纠正。虽然 ESRD 和透析对体液成分的影响已众所周知，但它们对呼出气成分的影响尚不确定。甲醇是结肠微生物组将不可吸收的复杂碳水化合物转化而来的。旨在限制钾摄入的果蔬饮食限制降低了膳食纤维的摄入量；膳食纤维摄入量的减少反过来又会减少甲醇的产生及其在呼出气体中的出现。在这项研究中，我们研究了透析过程中呼出气甲醇水平的变化。
10 名 ESRD 患者在 3 天和 2 天的透析间期进行 HD 治疗时接受了研究。在每个时间点，使用抽空罐收集 20 个呼出气和室内空气样本。10 名年龄匹配的正常受试者作为对照组。使用独特的 6 柱/检测器气相色谱系统对样品进行分析。
7 名食用肾脏饮食的 ESRD 患者的甲醇浓度（90 ± 29 ppbv）低于 3 名食用高纤维饮食的患者（340 ± 48 ppbv，P ≤.0006）和 10 名食用无限制饮食的对照组（202 ± 80 ppbv，P ≤.001）。HD 显著降低了呼出气甲醇（60% ± 12%），与血清尿素浓度的下降（70% ± 6%）平行。3 天的透析间隔比 2 天的透析间隔时，预透析甲醇浓度稍高。
果蔬饮食限制降低了 ESRD 患者肠道微生物菌群的甲醇生成。也许，甲醇是监测个体日常纤维摄入量的可靠呼出气生物标志物。HD 可显著降低呼出气甲醇，反映出其有效的去除作用。
