Lab Test: Folate (Serum) Level
- This test quantifies the folate level in the blood. It is used in patients who have megaloblastic anemia.
- Used to assess nutritional status, especially in alcoholics.
- Folate availability in pregnancy
- Evaluation of hemolytic disorders
- Anemia caused by folic acid deficiency - RBCs are abnormally large, causing a megaloblastic anemia.
- Workup in alcoholic patients - to assess nutritional status.
- Folic acid is needed for the adequate synthesis of certain purines and pyrimidines, which are precursors of deoxyribonucleic acid (DNA) needed for normal RBC and WBC production and function.
- It is also used in the synthesis of several amino acids.
- It is necessary for conversion of inactive 5-methyltetrahydrofolate to the active tetrahydrofolate, the active form of folate. The folate level depends on adequate dietary ingestion and normal intestinal absorption of this vitamin.
- The finding of a low serum folate means that the patient's recent diet has been subnormal in folate content and/or that recent absorption of folate has been subnormal. In time, folate levels will also drop in the tissues. It is advisable to determine RBC folate in addition to serum folate.
- Increased levels may indicate:
- Pernicious anemia, vegetarianism, or recent massive blood transfusion
- Decreased levels may indicate:
- Malnutrition, malabsorption syndrome (e.g., sprue, celiac disease), pregnancy, folic acid deficiency (megaloblastic) anemia, hemolytic anemia, malignancy, liver disease, chronic renal disease.
- Vitamin B12 - this is a measurement of the level of vitamin B12 in the serum and should be performed with a folic acid test.
- Complete blood cell count (CBC) - this is performed routinely and can identify megaloblastic anemia.
- A folate-deficient patient who has received a blood transfusion may have a falsely normal result.
- Because RIA is the method of choice for folic acid determination, radionuclide administration should b e avoided for at least 24 hours.
- Drugs that may cause decreased folic acid levels include: alcohol, aminopterin, aminosalicylic acid, ampicillin, antimalarials, chloramphenicol, erythromycin, estrogens, methotrexate, oral contraceptives, penicillin derivatives, phenobarbital, phenytoin, and tetracyclines.
- Draw the specimen before starting folate therapy.
- Collect a venous blood sample.
- Avoid hemolysis. Folate in the RBCs can falsely raise serum folate levels when hemolysis of the RBC occurs.
- Indicate on the laboratory slip any medications that may affect test results.
- Apply pressure or a pressure dressing to the venipuncture site and assess the site for bleeding.
- Explain the procedure to the patient.
- Tell the patient that no fasting is usually required. (However, some laboratories prefer an 8-hour fast.)
- Instruct the patient not to consume alcoholic beverages before the test.
Indications & Uses
What To Tell Patient Before & After
MESH Terms & Keywords