Vitamins, minerals and amino acids
Foliumzuur
The amount of folic acid (folate, vitamin B11) in the blood; to detect a deficiency, usually together with vitamin B12.
Everything about this testWhat it measures
Folic acid (folate, also called vitamin B11) is a B vitamin that is needed for cell division, the production of red blood cells and the development of the nervous system of an unborn child. It is found mainly in green vegetables, whole grain products, legumes and liver. The body has only a small store in the liver, so with too little intake or increased use, a deficiency can develop within 2 to 4 months. The test measures the folic acid in the blood; that value mainly follows the intake of the last few days to weeks.
- Folic acid deficiency due to a one-sided diet, excessive alcohol use or poor absorption in the bowel (for example with celiac disease or Crohn's disease)
- Anemia with red blood cells that are too large (macrocytic anemia), together with vitamin B12
- An increased need, for example during pregnancy and breastfeeding
High
A raised folic acid is almost always due to supplements, a multivitamin or fortified food and does not cause symptoms by itself. However, a lot of folic acid from tablets can hide a vitamin B12 deficiency: the anemia then improves, while nerve damage from the B12 deficiency can continue. That is why folic acid is usually assessed together with vitamin B12. A high value can also arise because red blood cells in the sample break down (hemolysis), since they contain a lot of folate.
Low
A low folic acid fits a deficiency; the cutoff differs per laboratory. According to the Dutch GP guideline (NHG) on anemia, a deficiency is usually due to too little folic acid in the diet, for example with excessive alcohol use. Other causes are poor absorption in the bowel (celiac disease, Crohn's disease), an increased need during pregnancy and breastfeeding and some medicines, such as methotrexate and certain epilepsy medicines. Symptoms of a deficiency are tiredness, shortness of breath and paleness due to anemia. A slightly low value after a few days of eating little does not yet mean that the stores are used up.
Preparation
- Do you take biotin (vitamin B8, often in hair and nail supplements)? Stop at least 2 days before the sample is taken, or 4 days for a high dose.
If your result is abnormal
With a low value, the GP also measures vitamin B12 and the blood count, if that has not been done yet, and looks for the cause, such as diet, alcohol, medicines or a bowel disease. With a deficiency, the GP usually prescribes folic acid tablets according to the NHG guideline and, with anemia, checks the Hb after 4 and after 8 to 10 weeks.
Reliability
A clearly low value fits a deficiency, but folic acid in the blood fluctuates with what you ate or took in the days before, so a tablet shortly before the blood draw can mask a deficiency. The Dutch GP guideline (NHG) on anemia advises always measuring folic acid together with vitamin B12, because giving folic acid with an unnoticed B12 deficiency can let nerve damage continue or get worse. With anemia, the result is assessed together with the blood count (Hb, MCV).
Limitations
- Supplements, multivitamins and fortified products raise the value; a folic acid tablet shortly before the blood draw gives too favorable a picture.
- Broken red blood cells in the sample (hemolysis, more common with a finger prick) give a falsely higher value.
- Alcohol, methotrexate, some epilepsy medicines and bowel diseases lower the value.
- Reference values differ per laboratory and measurement method.
How common is this
In general practice, anemia due to a vitamin B12 or folic acid deficiency newly occurs in about 2 in 1000 people per year. A folic acid deficiency is usually linked to a one-sided eating pattern or excessive alcohol use; in healthy people with a varied diet it is unusual. How often a folic acid deficiency without anemia occurs is not well known for the Netherlands.
Who is this useful for
Useful with anemia with red blood cells that are too large, with symptoms that fit a deficiency, with excessive alcohol use, with a very one-sided or restricted eating pattern (including with an eating disorder), with bowel diseases with poor absorption such as celiac disease and Crohn's disease and with long-term use of medicines that lower folic acid. When you want to have children, a measurement does not change the advice: everyone who wants to become pregnant is advised to take 400 micrograms of folic acid daily from about 4 weeks before conception until 10 weeks of pregnancy, regardless of diet. In healthy adults with a varied diet, routine measurement is not needed.
Downsides and risks
- A normal or high value due to a recent folic acid tablet or multivitamin can hide a deficiency.
- Anyone who starts taking folic acid on their own initiative without having vitamin B12 checked can mask a B12 deficiency.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results