A serum ferritin test determines how much iron is in the body. Normal ferritin levels for men range from 24 nanograms per milliliter (ng/mL) to 336 ng/mL. The normal levels for women is slightly less, ranging from 11 ng/mL to 307 ng/mL. The values are the same whether reported in nanograms per milliliter or micrograms per liter (mcg/L), with 100 ng/mL being the same as 100 mcg/L. The normal range can vary from laboratory to laboratory, depending on the type of ferritin test used and the normal values typically derived from that test.

Ferritin is a protein that stores iron. It is present in all cells of the body. Ferritin binds to iron, storing it in a non-toxic state. Normal ferritin levels are the amounts of ferritin that are to be expected in a healthy person. The levels are different for men and women, and they change according to age group.

A physician might order a serum ferritin test if other tests, such as hemoglobin or hematocrit levels, have abnormal results. Ferritin levels are tested by taking a blood draw, usually from the arm. There is no need for the patient to fast before a serum ferritin test.

Results that show higher-than-normal or lower-than-normal ferritin levels might be indicators of serious disorders or simply a temporary abnormal reading. When a patient has an abnormal ferritin test result, the physician usually will order further tests to determine the cause of the abnormal result while continuing to monitor the patient’s ferritin level.

Low ferritin levels might indicate anemia, vitamin C deficiency or hypothyroidism. The low levels might be the result of internal bleeding, such as from ulcers, hemorrhoids or heavy menstrual bleeding. A diet that is low in iron-containing foods might be responsible for low ferritin levels. The low levels can produce symptoms such as tiredness, weakness or restless leg syndrome.

High ferritin levels mean that there is an excess of iron in the blood. High levels might be caused by liver disease, leukemia or alcoholism. They also can be genetic in nature or might be caused by a diet high that is in iron. Inflammation might cause an increase in ferritin. Unlike low ferritin levels, high levels do not produce any symptoms.

Several factors can produce results temporarily outside the range of normal ferritin levels. A recent blood transfusion, any condition that causes inflammation or medicines such as birth control pills can affect the test results. Thyroid medications can interfere with the test results as well.