Folate deficiency

Folate deficiency classically presents as megaloblastic anaemia, with absence of neurological signs.

Common causes include malabsorption, drugs and toxins, states of increased demand, and dietary deficiency. Hereditary folate malabsorption and other inborn errors of folate metabolism are rare causes.

In early disease, haemoglobin and mean corpuscular volume are normal. In severe disease, patients present with symptomatic anaemia and pancytopenia.

Maternal folate deficiency is associated with fetal neural tube defects (NTDs).

Diagnosis is confirmed by the presence of low serum folate and/or low red blood cell folate. Elevated plasma homocysteine levels are helpful in situations of diagnostic difficulty.

Vitamin B12 (cobalamin) deficiency must be ruled out before initiating folic acid therapy, as the therapy may mask neurological manifestations of underlying vitamin B12 deficiency.

Oral folic acid is usually considered sufficient therapy. Underlying cause should be identified and treated.

Food fortification programmes instituted in some countries have decreased the incidence of folate deficiency and associated anaemia and fetal NTDs.

Megaloblastic anaemia without neuropathy is the classic manifestation of folate deficiency.[1]Herbert V. Experimental nutritional folate deficiency in man. Trans Assoc Am Physicians. 1962;75:307-20. http://www.ncbi.nlm.nih.gov/pubmed/13953904?tool=bestpractice.com

Folate, also known as vitamin B9, is present in green vegetables, legumes, and some fruits.

Deficiency arises due to malabsorption, drugs and toxins, increased demand, or dietary deficiency.[Figure caption and citation for the preceding image starts]: Megaloblastic macrocytic anemia: A. Peripheral blood smear of a patient with megaloblastic anemia. B. Peripheral blood smear of healthy individualPhotomicrograph from Mark J. Koury, MD; used with permission [Citation ends].