Red blood cell folate test: what the result means

Folic acid (folate, vitamin B9) is a vitamin needed to build new cells: it takes part in DNA synthesis and in making red blood cells in the bone marrow. The body does not store folate in large amounts, so its reserves depend on getting it regularly from food — leafy vegetables, legumes, citrus fruits — or from supplements. Serum folate shows the amount recently taken in with food, while folate in red blood cells reflects stores over a longer period and fluctuates less, which is why WHO treats it as the better marker. A deficiency can disturb the maturation of red blood cells and cause megaloblastic anaemia — a condition in which the cells become unusually large. Folate is especially important during pregnancy: a sufficient amount before conception and in early pregnancy reduces the risk of neural tube defects in the baby, for example spina bifida. The test is often assessed together with vitamin B12, because a lack of either one causes similar changes in the blood.

• When a complete blood count shows enlarged red blood cells of an unusual shape (megaloblastic anaemia)
• When there is tiredness, weakness, shortness of breath or pale skin — when anaemia is suspected
• When planning a pregnancy or at its beginning — to assess folate stores
• With digestive tract conditions that disturb the absorption of nutrients (for example coeliac disease)
• When the diet is one-sided or limited, or there is a history of alcohol use
• Together with a vitamin B12 test, when anaemia linked to a vitamin deficiency is suspected

A reduced amount of folate most often points to a poor diet, poor absorption or an increased need. According to MedlinePlus, a low level can indicate inadequate nutrition or a malabsorption syndrome (for example coeliac disease), or be linked with megaloblastic anaemia arising from a lack of folate or of B12.

• Not enough folate from food, or a one-sided diet
• Malabsorption syndromes, for example coeliac disease, which disturb the absorption of the vitamin in the digestive tract
• An increased need — pregnancy, intensive cell division
• Alcohol use, which reduces the absorption of folate and its stores

Possible symptoms are tiredness and weakness, pale skin, and shortness of breath.

What to discuss with a doctor: a complete blood count and the vitamin B12 level — so that it is clear whether the anaemia is caused by a lack of folate or of B12; the diet and any conditions that may disturb absorption, for example coeliac disease; and, when a pregnancy is being planned, the need for folate is discussed with a doctor in advance.