A hemoglobin A1C immunoassay method not affected by carbamylated hemoglobin

Area of Science:

• Clinical Chemistry
• Analytical Biochemistry
• Immunodiagnostics

Background:

• Hemoglobin A1C (HbA1C) measurement is crucial for diabetes management.
• Charge-based HbA1C assays are susceptible to interference from carbamylated hemoglobin (carb Hb).
• Carb Hb forms from urea dissociation to cyanate and subsequent reaction with hemoglobin.

Purpose of the Study:

• To evaluate a novel immunoassay for HbA1C, hypothesized to be resistant to carb Hb interference.
• To compare the performance of the immunoassay with an electrophoretic method in the presence of carb Hb.

Main Methods:

• In vitro carbamylation of hemoglobin.
• Electrophoretic separation and densitometry to assess HbA1C and carb Hb co-migration.
• Comparison of HbA1C results from immunoassay and electrophoresis using in vivo samples.

Main Results:

• Electrophoresis showed a 5-7 fold increase in HbA1C peak with carbamylation, while immunoassay results remained unaffected.
• In vivo studies revealed a proportional bias (y = 1.2x - 0.21 percent) favoring the electrophoretic system.
• Electrophoretic methods exhibited significant interference from carb Hb, unlike the tested immunoassay.

Conclusions:

• The novel immunoassay demonstrates robustness against carb Hb interference.
• Observed discrepancies between methods may be attributed to calibration issues rather than solely carb Hb interference.
• This finding has implications for accurate HbA1C monitoring in patients with potential Hb modifications.