In the case of abnormal hemoglobin present, what is the reason for caution in measuring Hgb A1c?

The presence of abnormal hemoglobin can lead to false elevation of Hb A1c results. Hb A1c is a measure of glycated hemoglobin, which reflects the average blood glucose levels over the past two to three months. Abnormal hemoglobins, such as those found in certain hemoglobinopathies (like sickle cell disease or thalassemia), can interfere with the assays used to measure Hb A1c.

When abnormal hemoglobin variants are present, they may interact differently with the methods used for the Hb A1c measurement. Some of these assays, particularly those that are high-performance liquid chromatography (HPLC)-based or immunoassay techniques, may erroneously attribute more glucose molecules to the hemoglobin, resulting in a falsely elevated value of Hb A1c. This can lead to misinterpretation of a patient’s glycemic control and management decisions.

Due to this potential for skewed results, it’s essential to approach Hb A1c measurement with caution in patients known to have abnormal hemoglobin types. In such cases, alternative methods, or additional tests may be necessary to accurately assess glycemic control.