Red Cell Folate Testing
Unwarranted and Overutilized in the Era of Folic Acid Supplementation
Folate deficiency manifests clinically in a variety of ways; notably it is strongly linked to an increased risk of neural tube defects and several observational and controlled trials have demonstrated that neural tube defects are significantly reduced with periconceptual folic acid supplementation. Individuals with folate deficiency may present clinically with unexplained, nonspecific neurological symptoms including dementia, weakness, and headaches. Folate and vitamin B12 deficiencies are both associated with a reduction in hemoglobin and megaloblastic changes in the bone marrow or other tissues. Megaloblastic anemia is the primary manifestation of folate deficiency, where erythrocytes become abnormally large and nucleated due to the lack of folate necessary for DNA synthesis and cell division.
Recognition of the significant relationship between folate and neural tube defects, cancer, and cardiovascular disease led to FDA-mandated fortification of breads, cereals, flours, pasta, and other grain products. Complete fortification was fully implemented in the United States in 1998, with the primary goal of reduction of neural tube defects. Overall, fortification has been successful and the prevalence of low serum folate among women of childbearing age declined from 20.6% in 1988-1994 to 0.8% in 2005-2006. The incidence of neural tube defects was reduced by 36% from 1995 to 2006 in the United States (10.8 to 6.9 per 10,000 pregnancies).
Jump to section:
- Selected Food Sources of Folate and Folic Acid*
- Causes of Folate Deficiency
- Laboratory Diagnosis of Folate Deficiency
- Folate and Vitamin B12 Deficiency
- Quantitation of Folate: Methods
- Differences Between Folate Immunoassays
- Analytical Imprecision: RBC Folate (CAP Surveys)
- Equivalence of Serum and RBC Folate
- Modern Folate Deficiency is Rare
- Mayo RBC/Serum Folate Orders 1999-2009