Label Mnemonic: FOLC
Epic code: LAB69
Downtime form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
6240 RCP
Specimen Instructions:
Collect a fasting sample.
Collection Medium:
Red top tube 5 mL (Clot Activator)
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
3 mL; red top or TWO Microtainer® devices.
Rejection Criteria:
Hemolyzed and plasma samples are NOT acceptable.
Delivery Instructions:
Deliver to laboratory immediately after collection.
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
Normal:  > 4.1 ng/mL
Indeterminate:  2.2 - 4.1 ng/mL
Deficient:  < 2.2 ng/mL

All enriched grains have been fortified with folic acid in the U.S. 
since 1998 and therefore the prevalence of folate deficiency is low 
(1%).  Testing for folate deficiency is strongly discouraged unless 
profound malnutrition is suspected and other causes of anemia have 
Interpretive Data:
This assay may be significantly impacted by high-dose biotin (>5 mg dose) taken within previous 12 hours. High concentrations of biotin may lead to falsely increased results. These concentrations may be found in patients taking over-the-counter supplements with biotin content much higher than nutritional requirements for biotin. Specimens should not be collected until at least 12 hours after the last dose.
Test Limitations:
The assay is unaffected by icterus (bilirubin is less than 29 
mg/dL), lipemia (triglycerides is less than 1500 mg/dL), hemolysis (Hb 
less than 40 mg/dL) and biotin is less than 40 ng/mL.  Criterion: 
recovery within plus or minus 0.5 ng/mL (1.1 nmol/l) at folate levels 
is less than 5 ng/mL (11 nmol/l), or within plus or minus 10% at 
levels is greater than 5 ng/mL (11 nmol/l).

No interference was observed from rheumatoid factors up to a 
concentration of 1000 U/mL.

In vitro tests were performed on 56 commonly used pharmaceuticals. No 
interference with the assay was found.

Folate assays of samples from patients receiving therapy with certain 
pharmaceuticals, e.g. methotrexate or leucovorin, are contraindicated 
because of the cross-reactivity of folate binding protein with these 

In rare cases interference due to extremely high titers of antibodies 
to streptavidin and ruthenium can occur.

For diagnostic purposes, the Folate findings should always be assessed 
in conjunction with the patient's medical history, clinical 
and other findings.
Electrochemiluminescence Immunoassay
CPT Code:
See also:
RBC Folate, Whole Blood