Comparative Analysis of HbA1c Estimation Using Immunoturbidimetry and High-Pressure Liquid Chromatography Methods in Non-Dialysis Chronic Kidney Disease Patients.

Background: Chronic kidney disease (CKD) concomitant with diabetes mellitus (DM), anemia and uremia. Thus, monitoring HbA1c levels presents a complex clinical challenge.

Methods: This analytical cross-sectional study was conducted from May 2022 to April 2023 at Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow. We compared HbA1c values obtained by the turbidimetric inhibition immunoassay (TINIA) and high-pressure liquid chromatography (HPLC) methods among non-dialysis CKD patients (n=127).

Results: HbA1c was not detectable among 27 patients by TINIA but measurable with HPLC, all being's anemic. The remaining 100 patients, it was detectable by both the methods. Among these 100 patients, linear regression analysis showed a very strong positive correlation between TINIA-HbA1c and HPLC-HbA1c (R2=0.861; p<0.0001). The agreement between methods was substantial (Cohen's kappa 0.657; p<0.0001). However, HbA1c levels were detected significantly higher with HPLC (Median 7.9, IQR 2.7) than that of TINIA (Median 7.0, IQR 2.9;p=0.025) in diabetics while the difference was not significant in non-diabetic group with both HPLC (Median 5.4,IQR 0.8) and TINIA (Median 5.1,IQR 1.1). Carbamylated Hb (CHb; as detected by HPLC as a side product) was correlated to both HbA1c by HPLC (r=0.299;p=0.007) and TINIA (r=0.336;p=0.006) as well as to serum urea levels (r=0.439;p<0.0001).

Conclusion: HPLC estimates all HbA1c patients in our study group while TINIA failed to do so in around 21.26% cases. The very low hemoglobin levels and high carbamylated hemoglobin were apparent as two most common causes. Also, the values with TINIA are significantly lower in comparison to HPLC among diabetics with CKD.