[Haemoglobin A1c measurements when to use and when not]

Area of Science:

• Clinical Chemistry
• Endocrinology
• Laboratory Medicine

Background:

• Glycated haemoglobin (HbA1c) is a key biomarker for diabetes diagnosis and management, reflecting average blood glucose over 2-3 months.
• Accurate HbA1c measurement is crucial for effective diabetes care.
• Various physiological and analytical factors can compromise HbA1c result validity.

Purpose of the Study:

• To review circumstances that can lead to spurious Haemoglobin A1c (HbA1c) results.
• To highlight the importance of recognizing potential interferences in HbA1c testing.
• To provide guidance on interpreting discordant clinical and laboratory findings.

Main Methods:

• Literature review of factors affecting HbA1c measurement.
• Analysis of erythrocyte turnover effects (e.g., anaemia).
• Examination of analytical interferences (e.g., haemoglobin variants).

Main Results:

• HbA1c is sensitive to erythrocyte turnover, impacting results irrespective of the measurement method.
• Analytical interferences, such as haemoglobin variants, can affect HbA1c depending on the assay used.
• Laboratories may identify and flag potential analytical interferences.

Conclusions:

• Spurious HbA1c results can arise from factors like anaemia or haemoglobin variants.
• When clinical presentation and HbA1c results are inconsistent, spurious results should be suspected.
• Fasting glucose measurement is recommended to verify glycaemic status in cases of suspected spurious HbA1c.