Vitamin B-9, 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 the natural form of vitamin B-9 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 vitamin B-9.
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 megaloblastic anemia. This is a type of anemia marked by fewer, but larger, red blood cells.
You may need 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
Fluttering heartbeat (palpitations) or rapid heartbeat
Dizziness and fainting
Nausea, vomiting, diarrhea, although these are rare
Your healthcare provider may also order a vitamin B-12 test. Both folate and B-12 are important for healthy red blood cells. A deficiency in either B-12 or folate can cause anemia.
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
For blood plasma or serum, a normal result ranges from 3 to 13 nanograms per milliliter (ng/mL) or 6.8 to 29.5 nanomoles per liter (nmol/L).
For red blood cells, a normal result ranges from 140 to 628 ng/mL or 317 to 1,422 nmol/L.
A test result that's lower than normal means you have a folate deficiency, and your healthcare provider may recommend folic acid supplements. Once you begin taking supplements, the folate deficiency will go away within a few months. Your healthcare 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 is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.
Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.
Many factors can contribute to a folate deficiency, including:
Being a vegetarian or not eating enough fresh vegetables and fortified grains
Drinking too much alcohol
Birth control pills
Nutrition absorption problems (Crohn's or celiac disease)
You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.