Some patients have a persistently low hemoglobin A1c. In these patients hemoglobin A1c cannot be used as a measure of glycemic levels.
Patient selection: hemoglobin A1c < 5%
Mechanism: decreased red blood cell lifespan
Possible causes of a persistently low hemoglobin A1c:
(1) chronic liver disease (chronic hepatitis, alcoholic hepatitis, cirrhosis)
(2) drugs (ribavirin, dapsone, erythropoietin)
(3) hemoglobinopathies (thalassemia, other)
(4) hereditary spherocytosis
(5) aplastic anemia
(6) chronic bleeding
(7) hemolytic anemia
(8) chronic renal failure
The presence of a persistently low hemoglobin A1c is associated with increased mortality, probably because of the underlying disease(s).
