What Clinical Laboratorians Should Do in Response to Extremely Low Hemoglobin A1c Results

Extremely low hemoglobin A1c (HbA1c) results below reference range are rare, and the causes and clinical implications associated with low HbA1c results are not well understood among clinical laboratorians. A case of extremely low HbA1c results was reported, in which liver cirrhosis, subacute hemorrhage and recent transfusion all contributed to the low result. This case illustrates when HbA1c should not be used as a clinically relevant diabetes marker. However, low or extremely low HbA1c (<5.0% or <4.0%) may occur in apparently healthy individuals. When this occurs, it is an independent risk factor associated with liver diseases, hospitalization, and all-cause mortality. From the clinical laboratory perspective, the clinical cause of extremely low HbA1c should be determined, and suggestions of different test utilization or increased health surveillance should be given to care providers. * Abbreviations : DCCT : Diabetes Control and Complications Trial HbA1c : hemoglobin A1c HPLC : high performance liquid chromatography ICU : intensive care unit NGSP : National Glycohemoglobin Standardization Program NHANES : National Health and Nutrition Examination Survey POCT : point of care testing RBC : red blood cell