[Determination of Hb A1c in chronic renal failure. Contribution of new methodologies]

Carbamylated haemoglobin arises from the non-enzymatic modification of haemoglobin by cyanate derived from spontaneous dissociation of urea. We studied the in vitro and in vivo interference of carbamylated haemoglobin in the assay of HbA1c by CLHP (ion exchange), affinity chromatography (IMX, Abbott) and immunoturbidimetry (Tina-Quant, Boehringer). For patients with chronic renal failure on continuous ambulatory peritoneal dialysis, CLHP assay of HbA1c gave an error of about +0.35% per 10 mmol/L of urea serum concentration. The IMX and especially Tina-Quant assays for measuring HbA1c were not sensitive to cyanate interference and constitute interesting alternatives for monitoring glycaemic balance in patients with chronic renal failure.