| Subject | Contents |
| Definition | A test that measures the amount of folate in the blood. |
| Alternative Names | Folate - test |
| How the test is performed | Adult or child: Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding . Infant or young child: The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. |
| How to prepare for the test | Fast for 6 hours before the test. The health care provider should be notified if you are using any drugs that can affect test results, including folic acid supplements (see "Special considerations"). Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:infant test or procedure preparation (birth to 1 year) toddler test or procedure preparation (1 to 3 years) preschooler test or procedure preparation (3 to 6 years) schoolage test or procedure preparation (6 to 12 years) adolescent test or procedure preparation (12 to 18 years) |
| How the test will feel | When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing. |
| Why the test is performed | This test is used to evaluate for folic acid deficiency . While it can be performed on either whole blood or red blood cells, the red blood cell folate is a more accurate reflection of chronic folate levels. Folic acid , one of the B vitamins , is necessary for synthesis of nucleotides (which are the building blocks of DNA). A deficiency of DNA synthesis is seen most readily in rapidly-dividing cells such as immature red blood cells. Red blood cells that are formed in the presence of deficient levels of folic acid are larger than normal, have reduced ability to carry oxygen, and shortened life spans. |
| Normal Values | The normal range is 2.7 to 17.0 ng/ml. Note: ng/ml = nanograms per milliliter |
| What abnormal results mean | Lower-than-normal levels may indicate: inadequate diet malabsorption syndrome (for example, sprue and celiac disease )malnutrition Additional conditions under which the test may be performed: anemia of folate deficiencymegaloblastic anemia |
| What the risks are | excessive bleedingfainting or feeling light-headed hematoma (blood accumulating under the skin) infection (a slight risk any time the skin is broken) multiple punctures to locate veins |
| Special considerations | Pregnancy increases the need for folic acid . Drugs that can decrease folate measurements include alcohol, aminopterin, aminosalicylic acid, ampicillin, antimalarials, chloramphenicol, erythromycin, estrogens, methotrexate, oral contraceptives (birth control pills), penicillin, phenobarbital, phenytoin, and tetracyclines. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. |
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