Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (980 page)

   When mean annual HbA
_1c
is <1.1 times ULN, renal and retinal complications are rare, but complications occur in >70% of cases when HbA
_1c
is >1.7 times ULN.

Increased In

   Fetal Hb above normal or 0.5% (e.g., heterozygous or homozygous persistence of HbF, fetomaternal transfusion during pregnancy)

   Chronic renal failure with or without hemodialysis

   Iron deficiency anemia

   Splenectomy

   Increased serum triglycerides

   Alcohol ingestion

   Lead and opiate toxicity

   Salicylate treatment

Decreased In

   Shortened RBC life span (e.g., hemolytic anemias, blood loss)

   Following transfusions

   Pregnancy

   Ingestion of large amounts (>1 g/day) of vitamin C or vitamin E

   Hemoglobinopathies (e.g., spherocytes), which produce variable increase or decrease depending on assay method.