CARBAMYLATED HEMOGLOBIN IN PRERENAL AZOTEMIA

Carbamylated hemoglobin (Carb Hb) levels were measured in 16 patients with a documented transient rise in BUN due to prerenal azotemia, in w hom BUN levels before and after the episode were normal. They were com pared with 13 controls. Carb Hb was expressed as carbamyl valine conce ntrations, which were significantly higher in the patients (166 mu g/g Hb) than in controls (95.3 mu g/g Hb, p < 0.01). The mean maximum BUN level in the patients was 51.8 +/- 23.9 mg/dl. There was a significan t correlation between the product of mean BUN level times the number o f days of BUN elevation, and the Carb Hb level (r = 0.5197; p < 0.05). There was no correlation between Carb Hb and either mean BUN level or maximum BUN level. Elevated Carb Hb was seen after a minimum of 4 day s' BUN elevation. Four patients had no elevation of Carb Hb despite el evated BUN levels. Conclusion: Carb Hb may be elevated after a minimum of 4 days' transient BUN elevation; Carb Hb is not useful in differen tiating between mild acute renal failure and prerenal azotemia.