CARBAMYLATED HEMOGLOBIN IN HEMODIALYSIS-PATIENTS

We have previously found that carbamylated hemoglobin (carHb) levels a re increased in chronic renal failure and correlate positively with bl ood urea nitrogen (BUN) levels and with the duration of exposure to ur ea. In a fashion analogous to glycosylated hemoglobin in diabetic pati ents, it is possible that carHb may better reflect BUN levels before h emodialysis (preBUN) and also between hemodialysis sessions, We theref ore tested the hypothesis that carHb could be a better index of adequa cy of hemodialysis than the urea reduction ratio (URR), Fifty hemodial ysis patients had carHb measured every 2 months for 14 months; the car Hb level was compared with URR and preBUN levels, as assessed by chang es in absolute numbers and trends of the BUN levels between hemodialys es. Mean URR was above 61% throughout the 14 months, Mean carHb levels did not change significantly during the study and were only weakly co rrelated with URR. However, there was a much better correlation betwee n predialysis BUN and carHb, suggesting that carHb levels reflect more accurately the changes in BUN between hemodialysis sessions, To furth er test this hypothesis, we subdivided the patients arbitrarily, depen ding on the change in preBUN between two consecutive carHb measurement s, We found significantly lower carl-lb levels when BUN decreased or r emained stable than when it increased or was persistently high. In pat ients with decreasing or stable BUN, carHb was significantly lower tha n in patients with persistently high or increasing BUN (carHb 81,5 +/- 3.6 mu g valine hydantoin [VH]/g Hb v 123.7 +/- 11,7 mu g VH/g Hb, re spectively; P < 0.001), URR was not different between groups. In addit ion to changes in BUN levels, carHb was correlated by multiple regress ion analysis with the presence of diabetes, weight, and plasma HCO3. T he relationship between diabetic patients and carHb levels was complex because such patients tend to have higher preBUN levels, higher prote in catabolic rate, and lower HCO3 levels. These results demonstrate th at carHb reflects the changes between dialysis BUN and may serve as a more accurate index of uremia control. Clinically, it appears that wel l-dialyzed patients have carHb levels lower than 100 mu g VH/g Hb. (C) 1997 by the National Kidney Foundation, Inc.