Appropriateness of the National Academy of Clinical Biochemistry recommendation of repeating HbA1c analysis for extreme results in clinical practice.

ABSTRACT

BACKGROUND: The National Academy of Clinical Biochemistry (NACB) recommends that the presence of a variant or modified haemoglobin be considered when any HbA1c result is below the lower limit of the reference interval or >or=15%. In those instances where a variant haemoglobin is suspected, repeat measurement using an alternative method is the usual course of action. In the present study, we undertook to determine the impact of this guideline on our identification of variant and modified haemoglobins. METHODS: All requests for HbA1c estimation received over a 32-month period, and which gave a result of <4% or >15% were re-analysed by a different method and the results compared. RESULTS: Over the 32-month period, 94 samples with a HbA1c result of <4% or >or=15% were identified. Of these, 80 were re-analysed using a different method. No chromatographic abnormalities were seen and there were no significant differences between the results obtained using the two methods. CONCLUSIONS: No variant or modified haemoglobins were identified in this study and this observation is likely to be representative of the ethnic makeup of our patient population. On the basis of this finding, we recommend that laboratories consider local factors when deciding whether to comply with the NACB guidelines.