Vitamin B9, folic acid test
This is a blood test to measure the concentration of folate in the liquid part of your blood, called serum, or in your red blood cells. The concentration in the red blood cells will be higher than in the serum.
Folate is a B vitamin naturally found in:
Leafy green vegetables, such as spinach, kale, collards, and romaine lettuce
Citrus fruits and juices
Dried beans, lentils, and peas
Many cereals, breads, and other grain products are fortified with folic acid, the synthetic version of folate.
Folate is needed to make red blood cells. It is also used to repair cells and to make DNA.
It also helps prevent cellular changes that may lead to cancer. Folate is also needed to help a baby's cells multiply during pregnancy. Low levels of folate during pregnancy can lead to brain or spine defects in the fetus. It can also lead to a type of anemia marked by fewer, but larger, red blood cells.
You may have this test to find out the cause of anemia, look at your nutritional status, or monitor a previous folate deficiency.
If you have anemia, you don't have enough red blood cells to carry oxygen to the cells in your body. A folate deficiency is just one cause of anemia. If you don't get enough folate or folic acid from food or vitamins, you may end up with a folate deficiency. Symptoms include:
Pale skin, gums, eyes, and nails
Mouth ulcers and a red, sore tongue
Shortness of breath
Numbness and tingling of fingers and toes
Dizziness and fainting
Nausea, vomiting, diarrhea, although these are rare
Your doctor may also order a vitamin B12 test. Both folate and B12 are important to for healthy red blood cells. A deficiency in either B12 or folate can cause anemia.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
For blood plasma or serum, a normal result ranges from 2 to 10 nanograms per milliliter (ng/mL) or 4 to 22 nanomoles per liter (nmol/L).
For red blood cells, a normal result ranges from 140 to 960 ng/mL or 550 to 2,200 nmol/L.
A test result that's lower than normal means you have a folate deficiency, and your doctor may recommend folic acid supplements. Once you begin taking supplements, the folate deficiency will go away within a few months. Your health care provider determines how much of a folic acid supplement you need based on your age and whether you are pregnant or breastfeeding.
Folate is water soluble, so any extra folate leaves your body in urine. But a buildup can sometimes happen during folic acid therapy.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Many factors can contribute to a folate deficiency, including:
Being a vegetarian
Drinking too much alcohol
Nutrition absorption problems (Crohn's or celiac disease)
You don't need to prepare for this test. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.