Incidental detection of a rare hemoglobin variant (Hemoglobin N Seattle) leading to undetectable levels of HbA1c in a diabetic female: a case report

Abstract

Glycosylated hemoglobin (GHb) is routinely used to monitor glycemic control over past 2-3 months in diabetics. As per the recommendations of the American Association of Clinical Endocrinologist, 2007 values should be maintained below 7% to prevent the risk of chronic complications. We report a case of a 55-year old female patient with spuriously low HbA1c values by high-performance liquid chromatography. Suspecting the presence of any abnormal hemoglobin, capillary zone electrophoresis was done which identified the presence of Hb variant corresponding to -Hb N Seattle. Our case highlights that clinical laboratories should be aware of limitations of their HbA1c assay methods as well as rule out any possible interfering Hb variants. 糖化血红蛋白(GHB)在糖尿病方面被常规用于监测过去2-3个月血糖控制。 根据美国临床内分泌医师学会2007年的建议，这个值应该被维持在7%以下，以防止慢性并发症的风险。 我们报告了一例55岁女性患者使用高效液体相色谱法测定假性低HbA1c值的病例。 因怀疑存在有某种异常血红蛋白，我们进行了毛细血管区带电泳，识别出存在对应于-Hb N Seattle的Hb变异体。 我们的病例强调了临床实验室应该意识到其HbA1c测定方法的局限性，并排除任何可能引起干扰的Hb变异体。