Folate

Alternative Names
  • Folic Acid

Test Code: 4019

CPT: 82746
Tests Included Folate
Use Folate is an essential vitamin vital to normal cell growth and DNA synthesis. It is present in a wide variety of foods such as dark, leafy vegetables, citrus fruits, yeast, beans, eggs, and milk. It is absorbed by the small intestine and stored in the liver. A folate deficiency can lead to megaloblastic anemia and ultimately to severe neurological problems.1,2,3 Used in conjuction with Vit B12 to help diagnose certain anemias that affect the absorption of B12.
Clinical Utility Folate deficiency can be caused by insufficient dietary intake, malabsorption or excessive folate utilization. Excessive utilization occurs very commonly during pregnancy. Alcoholism, hepatitis, or other liver-damaging diseases can also cause excessive folate utilization.1,2,3 Folate levels in both serum and red blood cells are used to assess folate status. The serum folate level is an indicator of recent folate intake. Red blood cell (RBC) folate is the best indicator of long term folate stores. A low RBC folate value can indicate a prolonged folate deficiency.

Folate and vitamin B12 are linked by the reaction pathway for methionine synthesis. A deficiency in either leads to a disruption of this pathway and to similar clinical symptoms.1,3 Another consequence of this common metabolic pathway is that a B12 deficiency disrupts the uptake of folate into red blood cells. This leads to a low RBC folate value even with adequate folate intake. For the above reasons, it is often necessary to measure both vitamins in a clinical workup. The treatment depends on which vitamin is deficient.
Intended Patient Population 18+ and Older Adult Males & Females
Patient Preparation None Specified
Sample Serum, Plasma
Tube Red, Green, Tiger
Volume 4mL Whole Blood (1mL Serum/Plasma)
Min Sample Volume 0.5 mLs
Reference Ranges M & F ≥ 18 yrs old; 3.56-20.00 ng/mL
Analytical Measurement Range 0.50 -20.00 ng/mL
Units ng/mL
Test Methodology Chemiluminescent Immunoassay
Test Turnaround Time 2 Days
Limitations None Specified
Shipping Requirements Refrigerated
Specimen Stability 7 Days RF
Reject Criteria Gross Hemolysis, Excess Light Exposure
Laboratory Developed Test (LDT) Yes
CMS Guidance None
References
  1. Donnelly, J. Folic Acid. Critical Reviews in Clinical Laboratory Sciences. 2001; 38(3): 183-223.
  2. Snow CF. Laboratory diagnosis of vitamin B12 and folate deficiency: A guide for the primary care physician. Arch Intern Med. 1999;159:1289-1298.
  3. Fairbanks VF, Klee GC. Biochemical aspects of hematology. In Burtis CA, Ashwood ER (eds): Tietz textbook of clinical chemistry, 3rd edition, pp 1642-1710, Philadelphia, WB Saunders, 1999.

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