Laboratory: Clinical Biochemistry  (SENDOUTS)
Test Name:
RBC FOLATE - (B)
Test Code: RFOL
Clinical Information:
Alternate Name(s): Pteroylglutamic Acid; Folic Acid
Description: RBC folate is no longer considered to meet the standard of care and routine testing is not recommended.
 
Mandatory folic acid fortification of foods (i.e. white flour, enriched pasta and cornmeal) was implemented in Canada in 1998, which led to significant increase in average population folate levels. Folate deficiency is now rare in Canada. 
 
If folate deficiency is suspected, it is reasonable to give oral folic acid (0.4 – 1 mg/day) without doing laboratory investigation for deficiency. See  BC Guidelines on Cobalamin (Vitamin B12) and Folate Deficiency for more information.

Test Indications: Test is not routinely available, and ordering should only be ordered by hematologists and gastroenterologists. Orders from other physicians may be accepted as they may be doing follow up monitoring for patients at high risk (e.g. post bariatric surgery).

 

“Folate” ordered on Dynacare requisition refers to Plasma Folate. Do NOT substitute those requests with RBC Folate. All valid requests must indicate “RBC Folate”.
Collection Devices:
If only one (1) tube can be collected, see notes in “Collection Information”
Specimen Required:

Collection Information: 
Collect TWO (2) full EDTA tubes.
Tube 1: freeze immediately (to be used for RBC folate)
 
Tube 2: Must be kept at room temperature (do not freeze) and send for hematocrit testing immediately. See  COMPLETE BLOOD COUNT (CBC) - (B) for details.

NOTE: Hematocrit result must be included with the specimen sent out for calculation.

IMPORTANT: When only one (1) tube can be collected (e.g. pediatric patient, anemic, etc.)

Transfer 1 mL to aliquot tube and freeze immediately to be sent out for folate testing. Remainder should be kept at room temperature and send immediately for hematocrit measurement.
Specimen Stability: 
Ambient: 2 hours
Refrigerated: 72 hours
Frozen: 1 month
Referral:
Whole Blood: 1.0 mL
Pediatric Whole Blood: 0.5 mL

Shipping & Storage: Freeze immediately. Store and send frozen.
Non-frozen samples will be rejected. Thawed samples are not suitable for testing.
Hematocrit result must be provided to ICL for calculation of RBC folate.

Referred Out Location: 
Specimen referred from HSC-MS5 to:
In-Common Laboratories (ICL)
57 Gervais Drive
North York, Ontario
M3C 1Z2
Telephone: (416) 422-3000
Test ID: RBCFOL
Test Name: Folate, Erythrocytes
Testing location: St. Michael's Hospital, Toronto ON
Requisition:
Reference Values:
Reference Intervals: 
RBC Folate: >1475 nmol/L
Hematocrit: 0.370-0.480
Method of Analysis: Chemiluminescence
Availability:
Within 1 Week
See Also:
More Information:
Do not centrifuge.  Fast freeze 4 mL of whole blood in plastic container WITHIN 4 HOURS of collection.  If specimen thaws, it is unsuitable for analysis.  Provide a Hematocrit result, required for calculation of RBC Folate.  The reported RBC Folate is not corrected for serum Folate.  Ship frozen to In-Common Laboratories.