Ferritin is a protein found inside cells that stores iron so your body can use it later. A ferritin test indirectly measures the amount of iron in your blood.

The amount of ferritin in your blood (serum ferritin level) is directly related to the amount of iron stored in your body.

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Your doctor may tell you to stop taking any drugs that may affect the test results.

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.

This test measures the amount of iron in the body. Iron is important for red blood cell production.

Additional conditions under which the test may be performed:

• Anemia of chronic disease

Male: 12-300 ng/mL

Female: 12-150 ng/mL

Note: ng/ml = nanograms per milliliter

The lower the ferritin level, even within the "normal" range, the more likely it is that the patient does not have enough iron.

Any inflammatory disorder can raise the ferritin level.

Higher-than-normal ferritin levels may be due to:

• Alcoholic liver disease
• Frequent transfusion of packed red blood cells
• Hemochromatosis
• Hemolytic anemia
• Hodgkin's lymphoma
• Megaloblastic anemia

• Long-term digestive tract bleeding
• Heavy menstrual bleeding
• Iron deficiency anemia

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

McPherson RA and Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: WB Saunders; 2007:78.

Hoffman R, Benz Jr. EJ, Shattil SJ, et al., eds. Hematology: Basic Principles and Practice. 4th ed. Philadelphia, Pa: Churchill Livingston; 2005:482.