In a patient with a known hemoglobin disorder, the doctor may want to specifically request that the HgA1C assay be done by boronate affinity chromatography.
There are several HgA1c assays or tests that do not give accurate readings with patients who may have an underlying hemoglobin disorder, also called a hemoglobinopathy.
There are several common hemoglobin disorders such as sickle cell trait and the thalassemias that are generally asymptomatic and generally of no consequence to the patient having it, but patients can have erroneous HgA1C measurements.