Don’t order serum folate testing in the absence of the following: anemia with red blood cell macrocytes or hypersegmented polynuclear neutrophils and a reasonable clinical suspicion of a nutritional deficiency such as an unsupplemented restrictive diet, severe Alcohol Use Disorder, or malabsorption.

Since 1998, all wheat white flours for food use sold in Canada and United States are enriched with folic acid as a mandatory legal requirement. The main reason for this supplementation is to prevent neural tube defects in newborns. Folates are found in processed food that contains white flour and in green leafy vegetables, legumes, some fruits and beans. Folate deficiency is therefore now encountered very rarely in Canada.

For most patients at risk for folate deficiency, like those with malabsorption, it is more practical and economical to treat with multivitamin supplements including folic acid, than to test for deficiency.

The Society of Obstetricians and Gynecologists of Canada recommends universal supplementation for women in the reproductive age group. Investigations are not required prior to initiating folic acid in women considering pregnancy.
For more information:

Ashraf MJ, Cook JR, Rothberg MB. Clinical utility of folic acid testing for patients with anemia or dementia. J Gen Intern Med. 2008 Jun;23(6):824-6. PMID: 18414954.

Brian M. Gilfix. Utility of measuring serum or red blood cell folate in the era of folate fortification of flour. Clinical Biochemistry. 2014 May;47(7-8):533-8. PMID: 24486651.

Hennessy-Priest K, Mustard J, Keller H, Rysdale L, Beyers J, Goy R, Randall Simpson J. Folic acid food fortification prevents inadequate folate intake among preschoolers from Ontario. Public Health Nutr. 2009 Sep;12(9):1548-55. PMID: 19200405.

MacFarlane AJ, Greene-Finestone LS, Shi Y. Vitamin B-12 and homocysteine status in a folate-replete population: results from the Canadian Health Measures Survey. Am J Clin Nutr. 2011 Oct;94(4):1079-87. PMID: 21900461.

Ray JG. Efficacy of Canadian folic acid food fortification. Food Nutr Bull. 2008 Jun;29(2 Suppl): S225-30. PMID: 18709897.

Theisen-Toupal J, Horowitz G, Breu A. Low yield of outpatient serum folate testing: eleven years of experience. JAMA Intern Med. 2014 Oct;174(10):1696-7. PMID: 25111789.

Wilson RD et al; Genetics Committee, Society of Obstetricians and Gynaecologists of Canada. Pre-conception Folic Acid and Multivitamin Supplementation for the Primary and Secondary Prevention of Neural Tube Defects and Other Folic Acid-Sensitive Congenital Anomalies.J Obstet Gynaecol Can. 2015 Jun;37(6):534-52. PMID: 26334606.