Folate
Serum Folate (Folic Acid)
What this test measures
Folate is a B vitamin that helps your body make red blood cells. It is especially important during pregnancy for the baby's development. You get folate from green vegetables, beans, and fortified foods.
Understanding the numbers
Typical range: 3.0-20.0 µg/L
Below 3 µg/L suggests deficiency. Red cell folate (285-790 µg/L) better reflects tissue stores.
- Deficient: 0–3 µg/L
- Low: 3–5 µg/L
- Normal: 5–20 µg/L
- High: 20–25 µg/L
Key numbers
- 3 µg/L — Below = deficient, treat
- 5 µg/L — Below = probable deficiency
Typical UK reference range. Serum folate reflects recent intake and can be normal after a couple of days of leafy greens; red cell folate reflects longer-term status. Always check B12 first before starting folate replacement — isolated folate treatment in unrecognised B12 deficiency can precipitate spinal cord damage.
Ranges can vary slightly between laboratories — your report may show slightly different numbers. This page does not read or interpret your result; your GP looks at it alongside your history and other tests.
What a higher-than-normal result can mean
- High folate is usually not a problem
- Often caused by taking folic acid supplements
- Your body removes excess folate in your urine
Questions you could ask your GP
- What dose of folic acid should I take, and for how long?
- Which foods can help boost my folate levels?
- Should I also have my B12 levels checked?
- If I am planning a pregnancy, when should I start taking folic acid?
Example stories
These are made-up examples to show how results are talked about in real appointments. They are not real patients.
Planning pregnancy
Pia was planning pregnancy. Her folate was 8.2, but she asked about supplements.
What the GP said: “Your folate is fine. Everyone planning pregnancy should take 400 µg folic acid daily from preconception through 12 weeks to reduce the risk of neural tube defects — this isn't about your starting level, it's a standard recommendation.”
What happened next: Pia started 400 µg folic acid three months before conception and continued until 13 weeks.
Folic acid in early pregnancy isn't prescribed based on blood levels — all women should take 400 µg daily in the first trimester, regardless of their folate. Some women with epilepsy, diabetes or previous neural tube defects need higher doses.
Deficient — poor diet after bereavement
Abdul had lost his wife, was eating poorly, and was tired. Folate 2.1, macrocytic anaemia with normal B12.
What the GP said: “You have folate deficiency from the change in your diet. We'll treat with folic acid 5 mg daily for four months, alongside social support and some help with meals.”
What happened next: His haemoglobin recovered and folate came back to normal; social services arranged meal support.
Folate deficiency in older adults often reflects life changes and poor diet. Treatment restores numbers quickly, but the underlying social or mental-health context matters too.
Alcohol-related deficiency
David drank around 50 units a week. Folate 2.5, MCV 108, haemoglobin 112.
What the GP said: “Alcohol interferes with folate and your diet is often poor when drinking heavily. We'll start folic acid 5 mg and refer to the alcohol service — the folate will recover but the drinking is the real target.”
What happened next: After reducing alcohol and folate replacement, his blood count normalised.
Chronic heavy drinking is one of the commonest causes of folate deficiency. Replacing folate is easy; supporting the patient to reduce alcohol is the harder and more important part.
Methotrexate — folate managed deliberately
Gulshan takes methotrexate for rheumatoid arthritis. Folate 6.8, FBC normal.
What the GP said: “Methotrexate lowers folate — we prescribe folic acid 5 mg once a week (not on the methotrexate day) to prevent side effects. Keep the routine and we'll check again in six months.”
Folate and methotrexate are managed actively together. Weekly folic acid reduces methotrexate side effects (nausea, mouth ulcers) without reducing its efficacy for the disease.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.