Folic acid test: what the result means (B9)

Folic acid, also called folate or vitamin B9, is a water-soluble vitamin that the body does not make itself — it has to come from food (leafy vegetables, legumes, citrus fruits) or from supplements. Folic acid takes part in making new cells and DNA, so it is especially important where cells renew quickly — in the bone marrow, where red blood cells are made, and during the development of a baby. That is precisely why the amount of folic acid matters when planning a pregnancy and during pregnancy — a deficiency is linked with neural tube defects. The blood test measures the amount of folic acid (folate) in serum, which reflects how much of this vitamin is circulating in the blood at the moment. The folic acid test is often done together with vitamin B12, because a lack of either one can cause a similar, megaloblastic anaemia, and the clinical picture often overlaps.

• When a complete blood count finds red blood cells of increased volume (a high MCV) or other signs typical of megaloblastic anaemia
• When there is tiredness, weakness or other signs of anaemia and the cause is not yet clear
• When planning a pregnancy or during pregnancy — to assess folic acid stores
• With digestive tract conditions (for example coeliac disease) or other absorption problems
• When the diet is limited or unbalanced (for example low in fresh vegetables)
• Together with a vitamin B12 test, while working out the cause of anaemia

A reduced amount of folic acid most often points to a poor diet, an absorption problem or an increased need in the body. Over time a deficiency can cause megaloblastic anaemia — a condition that a lack of vitamin B12 also causes, which is why both markers are assessed together.

• A poor diet, with few leafy vegetables, legumes or citrus fruits
• Absorption problems in the digestive tract, for example coeliac disease
• An increased need — pregnancy or rapid growth
• Long-term alcohol use, which disturbs the absorption of folic acid

Possible symptoms are tiredness and a lack of energy, tingling in the hands or feet, a sore, reddened lining of the tongue, small ulcers in the lining of the mouth, and muscle weakness.

What to discuss with a doctor: a complete blood count and MCV — whether megaloblastic anaemia is already present; a vitamin B12 test, because a lack of either one can cause a similar clinical picture; the diet and any digestive tract conditions that disturb absorption; and a discussion with your doctor about whether a folic acid supplement is needed and for how long to take it.

At the Medicina practica laboratory, a folic acid test costs from €21 (September 2026 pricing). At other laboratories the price may differ slightly.