Inaccurate Hemoglobin A1c Values in the Presence of Hemoglobin Wayne Variant

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 758-785-Diabetes Case Reports: Type 1, Type 2, MODY & Complications
Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-760
Michael Roger Brennan*1, Veronica Luzzi2, Fred Whitehouse2 and Pendar Farahani2
1William Beaumont Hospital, Grosse Pointe, MI, 2Henry Ford Hospital, Detroit, MI
Background: Hemoglobin A1c (HbA1c) values greater than 6.5% are diagnostic for diabetes mellitus.  The presence of certain hemoglobin (Hb) variants may lead to inaccurate HbA1c values depending on the method of detection.  When using BioRad Variant II ion-exchange high-pressure liquid chromatography (HPLC), Hb Wayne appears to elute at a retention time that causes overestimation of HbA1c values. We report the first two cases of elevated HbA1c when using BioRad Varient II HPLC due to the presence of Hb Wayne variant. 

Clinical Case: A 29-year-old African American woman presents to an endocrinologist’s office with concern because she was told she has diabetes.  The diagnosis was based on two HbA1C values of 12.5% and 12.7% using the BioRad Variant II HPLC method taken months apart.  She disputed this diagnosis because her home blood glucometer values remained normal without intervention.  The patient’s HbA1c assessed using an immunoassay analysis method in the outpatient setting was 5.1%.  This value correlated with her home glucometer readings.  The woman’s father had been told he had diabetes based on laboratory HbA1c values of 10.8%, 10.5% and 10.7% taken several months apart.  The patient’s father also disputed the diagnosis and refused treatment of diabetes.  The father’s point of care testing using immunoassay techniques reported a HbA1c value of 5.2%. Fasting and 2-hour post 75-gram oral glucose tolerance testing of the woman and her father were normal, further supporting that neither had diabetes.  To investigate these diagnostic discrepancies analysis for hemoglobin variants using capillary electrophoresis was performed on both the woman and her father.  The capillary electrophoresis revealed the presence of Hb Wayne variant in both patients. 

HPLC techniques determine HbA1c using particle size and charge.  Hb Wayne is a variant of human Hb in which the carboxyl-terminal region of the alpha chain contains an unusual sequence that causes a frame shift (1).  Under the conditions used in the BioRad Variant II HPLC, Hb Wayne migrates at the same elution time as HbA1c and apparently overestimates the HbA1c value.  As demonstrated by these cases, Hb variants can interfere with HbA1c analysis (2).

Conclusion:  Hb Wayne appears to interfere with BioRad Variant II HPLC analysis of HbA1c causing the value to become misleading.  Individuals with Hb Wayne variant should be tested via techniques other than HPLC to determine if they have diabetes.

(1) Seid-Akhavan M. et al., Hemoglobin Wayne: A Frameshift Mutation Detected in Human Hemoglobin Alpha Chains. Proc Natl Acad Sci USA Mar; 73(3): 882-6.(2) Little R. R., Roberts, W., A Review of Variant Hemoglobins Interfering with Hemoglobin A1c Measurement  J Diabetes Sci Technol Vol 3, Issue 3, May 2009

Disclosure: MRB: , Novo Nordisk. Nothing to Disclose: VL, FW, PF

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm