Vitamin A test

• Illustrations
• Alternative names
• Definition
• How the test is performed
• How to prepare for the test
• How the test will feel

• Why the test is performed
• Normal Values
• What abnormal results mean
• What the risks are
• Special considerations

Alternative names    Return to top

Definition    Return to top

The vitamin A blood test measures the amount of vitamin A (see also beta-carotene).

How the test is performed    Return to top

Adult or child:

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to fill with blood. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. The tourniquet is then removed to restore circulation. After 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. A bandage may be applied to the puncture site if there is any bleeding.

How to prepare for the test    Return to top

Fast for 4 hours before the test.

Infants and children:

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

• 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    Return to top

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    Return to top

To investigate the possibility of vitamin A deficiency or excess, both of which are rare in the developing world.

Normal Values    Return to top

Normal values range from 50 to 200 mcg/dl. Normal value ranges may vary slightly among different laboratories.

What abnormal results mean    Return to top

Abnormal values reflect a deficiency of vitamin A that may be associated with:

• Developmental aberrations of bones or teeth in young children
• Dry or inflamed eyes
• Hair loss
• Loss of appetite
• Malabsorption syndrome (for example, celiac disease, sprue)
• Night blindness
• recurring infections
• Skin rashes
• Steatorrhea (fat malabsorption -- inadequate absorption of fats from the intestinal tract)

What the risks are    Return to top

Risks associated with venipuncture are slight:

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

Special considerations    Return to top

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.