Measurement of Hba1C in patients with chronic renal failure

BackgroundCarbamylated hemoglobin (carbHb) is reported to interfere with measurement and interpretation of HbA1c in diabetic patients with chronic renal failure (CRF). There is also concern that HbA1c may give low results in these patients due to shortened erythrocyte survival.MethodsWe evaluated the effect of carbHb on HbA1c measurements and compared HbA1c with glycated albumin (GA) in patients with and without renal disease to test if CRF causes clinically significant bias in HbA1c results by using 11 assay methods. Subjects included those with and without renal failure and diabetes. Each subject's estimated glomerular filtration rate (eGFR) was used to determine the presence and degree of the renal disease. A multiple regression model was used to determine if the relationship between HbA1c results obtained from each test method and the comparative method was significantly (p < 0.05) affected by eGFR. These methods were further evaluated for clinical significance by using the difference between the eGRF quartiles of > 7% at 6 or 9% HbA1c. The relationship between HbA1c and glycated albumin (GA) in patients with and without renal failure was also compared.ResultsSome methods showed small but statistically significant effects of eGFR; none of these differences were clinically significant. If GA is assumed to better reflect glycemic control, then HbA1c was approximately 1.5% HbA1c lower in patients with renal failure.ConclusionsAlthough most methods can measure HbA1c accurately in patients with renal failure, healthcare providers must interpret these test results cautiously in these patients due to the propensity for shortened erythrocyte survival in renal failure.

► Elevated carbamylated hemoglobin is common in patients with renal failure.
► Carbamylated hemoglobin has been reported to interfere with some HbA1c methods.
► None of the methods evaluated showed clinically significant assay interference.
► HbA1c results were ~ 1.5% HbAlc lower in renal failure vs. non-RF patients.
► HbA1c results for patients with renal disease must be interpreted with caution.