[Sources of error when using haemoglobin A1c].

Abstract

BACKGROUND:

Measurement of glycated haemoglobin A1 in whole blood (b-HbA1c) can be used in both diagnosing and following up patients with diabetes. Correct interpretation of analytical results is contingent on agreement between average plasma glucose (p-glucose) and b-HbA1c. This article provides an overview of factors that may result in a discrepancy between average glucose concentration and b-HbA1c.

METHOD:

Literature search in PubMed to identify scientific articles that describe strengths and weaknesses of b-HbA1c.

RESULTS:

The b-HbA1c reading usually provides a good picture of average p-glucose for the preceding two to three months. Patients who are being treated with iron/vitamin B12 supplements, have liver failure, haemolytic anaemia or bleeding usually have a lower b-HbA1c than their p-glucose level would suggest. With increasing patient age, B12 deficiency or iron deficiency anaemia, higher values of b-HbA1c are seen for the same p-glucose level. Some ethnic groups have a higher b-HbA1c than their average p-glucose would suggest, but the risk of long-term complications appears generally to be more closely associated with b-HbA1c than with the glucose level. Pregnancy, renal failure or haemoglobinopathies may make the b-HbA1c value unreliable as an expression of average p-glucose.

INTERPRETATION:

Correct interpretation of b-HbA1c is conditional on the requisitioner being aware of possible sources of error. If the patient is suspected to have a condition that leads to lack of consistency between b-HbA1c and average p-glucose, glucose-based criteria must be used in diagnosing diabetes.

• Authors: Thea Berge Vikøren, Jens Petter Berg, Tore Julsrud Berg
• Journal: Tidsskrift for den Norske laegeforening : tidsskrift for praktisk medicin, ny raekke (Tidsskr Nor Laegeforen) Vol. 134 Issue 4 Pg. 417-21 (Feb 25 2014) ISSN: 0807-7096 [Electronic] Norway
• Vernacular Title: Feilkilder ved bruk av hemoglobin A1c.
• PMID: 24569741 (Publication Type: Journal Article, Review)

Chemical References

• Biomarkers
• Blood Glucose
• Glycated Hemoglobin A

Topics

• Biomarkers (blood)
• Blood Chemical Analysis (standards)
• Blood Glucose (analysis, metabolism)
• Diabetes Mellitus (blood, ethnology)
• Glycated Hemoglobin (analysis, metabolism)
• Humans