Tarif N, Shaykh M, Stim J, Arruda J A, Dunea G
Division of Nephrology, Cook County Hospital, the University of Illinois at Chicago, 60612, USA.
Am J Kidney Dis. 1997 Sep;30(3):361-5. doi: 10.1016/s0272-6386(97)90280-8.
We have previously found that carbamylated hemoglobin (carHb) levels are increased in chronic renal failure and correlate positively with blood urea nitrogen (BUN) levels and with the duration of exposure to urea. In a fashion analogous to glycosylated hemoglobin in diabetic patients, it is possible that carHb may better reflect BUN levels before hemodialysis (preBUN) and also between hemodialysis sessions. We therefore tested the hypothesis that carHb could be a better index of adequacy of hemodialysis than the urea reduction ratio (URR). Fifty hemodialysis patients had carHb measured every 2 months for 14 months; the carHb level was compared with URR and preBUN levels, as assessed by changes in absolute numbers and trends of the BUN levels between hemodialyses. Mean URR was above 61% throughout the 14 months. Mean carHb levels did not change significantly during the study and were only weakly correlated with URR. However, there was a much better correlation between predialysis BUN and carHb, suggesting that carHb levels reflect more accurately the changes in BUN between hemodialysis sessions. To further test this hypothesis, we subdivided the patients arbitrarily, depending on the change in preBUN between two consecutive carHb measurements. We found significantly lower carHb levels when BUN decreased or remained stable than when it increased or was persistently high. In patients with decreasing or stable BUN, carHb was significantly lower than in patients with persistently high or increasing BUN (carHb 81.5 +/- 3.6 microg valine hydantoin [VH]/g Hb v 123.7 +/- 11.7 microg VH/g Hb, respectively; P < 0.001). URR was not different between groups. In addition to changes in BUN levels, carHb was correlated by multiple regression analysis with the presence of diabetes, weight, and plasma HCO3. The relationship between diabetic patients and carHb levels was complex because such patients tend to have higher preBUN levels, higher protein catabolic rate, and lower HCO3 levels. These results demonstrate that carHb reflects the changes between dialysis BUN and may serve as a more accurate index of uremia control. Clinically, it appears that well-dialyzed patients have carHb levels lower than 100 microg VH/g Hb.
我们之前发现，慢性肾衰竭患者的氨甲酰化血红蛋白（carHb）水平升高，且与血尿素氮（BUN）水平以及尿素暴露时长呈正相关。与糖尿病患者的糖化血红蛋白类似，carHb有可能能更好地反映血液透析前（preBUN）以及透析间期的BUN水平。因此，我们检验了这样一个假设：相较于尿素清除率（URR），carHb可能是血液透析充分性的一个更好指标。50名血液透析患者在14个月内每2个月测量一次carHb；将carHb水平与URR以及preBUN水平进行比较，后者通过透析期间BUN水平的绝对数值变化和趋势来评估。在整个14个月中，平均URR高于61%。研究期间平均carHb水平没有显著变化，且与URR仅呈弱相关。然而，透析前BUN与carHb之间的相关性更好，这表明carHb水平能更准确地反映透析间期BUN的变化。为了进一步验证这一假设，我们根据两次连续carHb测量之间preBUN的变化对患者进行了任意分组。我们发现，当BUN下降或保持稳定时，carHb水平显著低于BUN升高或持续处于高位时。在BUN下降或稳定的患者中，carHb显著低于BUN持续处于高位或升高的患者（carHb分别为81.5±3.6微克缬氨酸乙内酰脲[VH]/克血红蛋白与123.7±11.7微克VH/克血红蛋白；P<0.001）。各组之间URR没有差异。除了BUN水平的变化外，通过多元回归分析发现carHb与糖尿病的存在、体重和血浆HCO3相关。糖尿病患者与carHb水平之间的关系较为复杂，因为这类患者往往有更高的preBUN水平、更高的蛋白质分解代谢率以及更低的HCO3水平。这些结果表明，carHb反映了透析期间BUN的变化，可能是尿毒症控制的一个更准确指标。临床上，透析充分的患者似乎carHb水平低于100微克VH/克血红蛋白。
