Reporting variant hemoglobins discovered during hemoglobin A1c analysis - common practices in clinical laboratories

Patients with variant hemoglobins may receive inaccurate results by some HbA(1c) methods. We examined reporting practices of clinical laboratories with respect to variant hemoglobins and limitations of methodology.

A survey of reporting practices was published in LabMedicine, and circulated to directors of Clinical Laboratory Sciences programs. Websites of reference laboratories were reviewed.

One hundred thirty-five laboratories from 42 US states responded. 61.5% of those laboratories report only HbA(1c) value and reference interval; 5% of laboratories include methodology. 51% of laboratories use IE-HPLC, 47% use immunoassay and 2% use boronate affinity chromatography. Of laboratories using IE-HPLC, 39% routinely report the presence of hemoglobin variants, and 10% report variants only if they cause interference with the test. Of laboratories using immunoassay, only one appends the disclaimer that elevated HbF interferes with test results. All of the major reference laboratories report methodology on their websites; only 2 can detect hemoglobin variants. Six out of 7 reference laboratories state limitations of methodology on their websites.

There is no standardized reporting format for HbA(1c) that includes methodology, test limitations or notification of variant hemoglobins. An algorithm for detection and reporting of variant hemoglobins and test methodology is proposed based on best practices.