TEMPORAL CHANGES AND REVERSIBILITY OF CARBAMYLATED HEMOGLOBIN IN RENAL-FAILURE

The detection of carbamylated hemoglobin (CarHb) is known to be useful in determination of the chronicity of uremia. However, the time cours e of the in vivo reaction between isocyanic acid and terminal valine r esidues of the hemoglobin chain is nor clearly defined. To assess the temporal relationship and reversibility of carbamylation, we prospecti vely measured CarHb as micrograms of valine hydantoin per gram of hemo globin (mu g VH/g Hb) by high-performance liquid chromatography in 37 patients with acute renal failure (ARF), 53 patients with chronic rena l failure (CRF), and six patients with successful kidney transplant. P atients with ARF had a lower median CarHb concentration (53.2 mu g VH/ g Hb; range, 24.6 to 97.1 mu g VH/g Hb) than those with CRF (115.0 mu g VH//g Hb; range, 34.6 to 286.5 mu g VH/g Hb; P < 0.01), but had a hi gher value (53.2 mu g VH/g Hb; range, 24.6 to 97.1 mu g VH/ g Hb) than 31 normal controls (36.6 mu g VH/g Hb; range, 19.9 to 62.9 mu g VH/g Hb; P < 0.05). In patients with ARF, the CarHb concentration positivel y correlated with the number of days of illness (r = 0.74; P < 0.01). The patients with ARF of 10 or more days' duration had a higher CarHb concentration (68.7 mu g VH/g Hb; range, 36.0 to 93.9 mu g VH/g Hb) th an those with a shorter duration of ARF (33.7 mu g VH/g Hb; range, 24. 6 to 55.8 mu g VH/g Hb; P < 0.01) despite similar blood urea nitrogen and serum creatinine values. However, they had a lower concentration o f CarHb (68.7 mu g VH/g Hb; range, 36.0 to 93.9 mu g VH/g Hb) than CRF patients with comparable serum creatinine values (112.5 mu g VH/g Hb; range, 34.6 to 286.5 mu g VH/g Hb; P < 0.01). In patients with a kidn ey transplant, CarHb concentration declined by 19.7% (range, 12.3% to 35.6%) within 2 to 3 weeks after receiving the graft, while the level of hemoglobin increased by 25% (range, 4.0% to 46.6%) during the same period. Therefore, the total blood CarHb (CarHb x hemoglobin concentra tion) was not significantly changed. We concluded that the in vivo rea ction of carbamylation of hemoglobin progressed during the period of u remia, and there might exist some irreversible preformed CarHb in adva nced stages of CRF. (C) 1997 by the National Kidney Foundation, Inc.