Investigating the Factors Affecting the Commutability of Hemoglobin A_1C Frozen Pooled Blood Materials

Measurement of hemoglobin A_1C (HbA_1C) is essential for the diagnosis and treatment of diabetes mellitus (DM). Processed blood materials (PBMs), such as frozen pooled blood (FPB), are commonly used for External Quality Assessment (EQA). However, their commutability may be affected by factors such as hemolysis and matrix modification. This study evaluated FPB commutability and identified the factors influencing its performance in HbA_1C measurements.

HbA_1C contents in 24 clinical blood samples (CBSs) and 10 PBMs, including FPBs, single-donor blood (SDB), and in vitro glycated blood (IGB), were analyzed using enzymatic (EN), capillary electrophoresis (CE), cation-exchange high-performance liquid chromatography (CE-HPLC), turbidimetric immunoassay (TI), and boronate affinity HPLC (BA-HPLC). EN served as the reference measurement procedure. Commutability was assessed using Deming regression and a 95% prediction interval. The hematocrit (HCT), visual appearance, plasma absorbance (PA), hemolysis index (HI), pH, and debris cells (DC) were analyzed.

FPB1 and SDB were commutable across all measurement procedures. FPB2 and FPB4 were commutable with CE, CE-HPLC, and TI but non-commutable with BA-HPLC when HbA_1C was ≥ 6.23%, as data points fell outside the tolerance limits of the Deming regression lines. Non-commutable PBMs showed higher PA and HI along with lower pH. DC affected HbA_1C quantification using CE-HPLC.

Hemolysis, as assessed by PA and HI, affects FPB commutability. These factors should be considered in EQA programs, particularly for BA-HPLC. HCT and DC did not directly affect commutability; however, maintaining appropriate HCT levels and monitoring DC-related chromatographic interference are crucial for ensuring FPB reliability in HbA_1C comparisons.