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HelpTest ID FOL Folate, Serum
Useful For
Investigation of suspected folate deficiency
Special Instructions
Method Name
Competitive-Binding Receptor Assay
Reporting Name
Folate, SSpecimen Type
SerumContainer/Tube:
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 0.6 mL
Collection Instructions:
1. Fasting (8 hours)
2. Serum gel tubes should be centrifuged within 2 hours of collection.
3. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.
Additional Information: Do not order on patients who have recently received methotrexate or other folic acid antagonists.
Forms: If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
Neurology Test Request Form-General (T732) (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf)
Benign Hematology Test Request Form (T755) (http://www.mayomedicallaboratories.com/it-mmfiles/benign-hematology-test-request-form.pdf)
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 90 days |
Clinical Information
The term folate refers to all derivatives of folic acid. For practical purposes, serum folate is almost entirely in the form of N-(5)-methyl tetrahydrofolate.(1)
Approximately 20% of the folate absorbed daily is derived from dietary sources; the remainder is synthesized by intestinal microorganisms. Serum folate levels typically fall within a few days after dietary folate intake is reduced and may be low in the presence of normal tissue stores. RBC folate levels are less subject to short-term dietary changes.
Significant folate deficiency is characteristically associated with macrocytosis and megaloblastic anemia. Lower than normal serum folate also has been reported in patients with neuropsychiatric disorders, in pregnant women whose fetuses have neural tube defects, and in women who have recently had spontaneous abortions.(2) Folate deficiency is most commonly due to insufficient dietary intake and is most frequently encountered in pregnant women or in alcoholics.
Other causes of low serum folate concentration include:
-Excessive utilization (eg, liver disease, hemolytic disorders, and malignancies)
-Rare inborn errors of metabolism (eg, dihydrofolate reductase deficiency, formiminotransferase deficiency, 5,10-methylenetetrahydrofolate reductase deficiency, and tetrahydrofolate methyltransferase deficiency)
Reference Values
≥4.0 mcg/L
<4.0 mcg/L suggests folate deficiency
Cautions
Patients with combined deficiency of folate and iron may not demonstrate the erythrocyte macrocytosis that is typical of folate deficiency anemia. In these patients, however, the red cell distribution width (RDW) will typically be elevated.
Nonfasting specimens yield falsely elevated results.
Recent folic acid administration or dietary folate intake could result in normal or elevated values and possibly mask an underlying folate deficiency.
Folates other than N-(5)-methyltetrahydrofolate and folic acid antagonists (such as methotrexate) may, under some circumstances, be present in serum and will also be measured by this method.
Some patients who have been exposed to animal antigens, either in the environment or as part of treatment or imaging procedures, may have circulating antianimal antibodies present. These antibodies may interfere with the assay reagents to produce unreliable results.
Day(s) Performed
Monday through Friday; 5 a.m.-12 a.m.
Saturday; 6 a.m.-6 p.m.
Report Available
Same Day/1 dayPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82746