Haemoglobin A1c - red cell

Last updated: Friday, 24, June, 2011

The item number and fee shown are for Australia only. The fee is the Medicare Schedule Fee.

Laboratories may in some circumstances charge above this fee.

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Item Process
Specimen

5 mL blood in lithium heparin or EDTA tube.

Method

Chromatography, electrophoresis, immunoassay.

Note: from July 2011 laboratories are recommended to report HbA1c in both the usual % units and the new Systeme International (SI) / IFCC units of mmol/mol.

Reference Interval

HbA1c: 3.5 - 6.0%(15-42 mmol/mol)

Application

Diabetes mellitus: monitoring of glycaemia over previous three months.

Interpretation

The result reflects the average glucose concentration over the life of the red cells although some methods give a falsely high reading if the patient is hyperglycaemic when the blood is collected.

Response to HbA1c concentrations will vary depending on the clinical status and treatment of the patient. See reference in Medical Journal of Australia

Levels will be lower than appropriate for the degree of diabetic control in the presence of any condition with reduced red cell life. Measurement after recent transfusion or treatment of iron deficiency or with reticulocytosis should be avoided.

Note some methods are affected by the presence of haemoglobinopathies.

In any case where blood glucose results from laboratory or home testing are not consistent with the HbA1c result further investigation should be undertaken to assess for haemoglobinopathies or abnormal red cell survival.

See also Fructosamine

Reference

Krishnamurti U and Steffes MW. Clin Chem 2001; 47(7):1157-65.

WAH Chung et al. Med J Aust 2009; 191: 339–344

Recommended Changes in HbA1c Reporting Units for Australian Laboratories http://www.aacb.asn.au/admin/?getfile=2802