Serum ferritin and serum iron blood tests determine iron levels through different means. Your serum ferritin level is the amount of iron in your body, while serum iron measures the level of iron in your blood. Testing can be crucial, according to KidsHealth.org, as iron can build up to damaging levels in your body before symptoms appear.
Iron is stored inside a protein called ferritin, which is found in many of your body's cells. By extracting a blood sample---not the actual protein---a serum ferritin test provides information about the iron level inside your body, according to the U.S. National Institutes of Health (NIH). A serum ferritin test can diagnose anaemia, when you are iron-deficient, or hereditary hemochromatosis, which causes your body to store too much iron.
Your doctor may order a serum iron test to determine if you have low iron or an iron deficiency. This test---which measures the exact iron level in your blood---can also diagnose hereditary hemochromatosis, according to KidsHealth.org.
Serum ferritin measures the amount of iron in body cells and serum iron measures iron levels in the blood, so they have different "normal" ranges. A normal test result for serum ferritin will be measured in nanograms per millilitre: 12 to 300 ng/ml for men and 12 to 150 ng/ml for women.
The normal test result range for serum iron is measured in micrograms per decilitre: 60 to 170 mcg/dl for both men and women. However, according to Drugs.com, the serum iron level ranges may vary depending upon the lab used.
The serum iron test should be conducted in the mornings, when iron levels are highest, according to Drugs.com. No specific time of day is preferred for serum ferritin testing, but an inflammatory disorder, such as asthma or arthritis, could inflate your serum ferritin level.
Since each test is attempting to measure iron levels from a different source, and for different reasons, abnormal results will also differ in cause. For example, higher-than-normal serum iron results could indicate hepatitis, iron poisoning or vitamin B deficiencies. Higher-than-normal serum ferritin results might be from Hodgkin's lymphoma or liver disease, reports the NIH. Lower-than-normal results of the serum ferritin test might be from long-term digestive tract bleeding, while lower-than-normal serum iron results could be due to pregnancy or heavy menstrual bleeding.