What does serum ferritin primarily measure?

Serum ferritin is a protein that stores iron in the body and releases it in a controlled manner. Therefore, when serum ferritin levels are measured, they provide an indication of the amount of iron stored in the body. This makes it a crucial marker for evaluating iron deficiency or overload.

In the context of assessing nutritional status or diagnosing conditions such as iron deficiency anemia, low ferritin levels typically indicate low iron stores, which can lead to decreased hemoglobin levels and subsequently impact oxygen transport in the bloodstream. However, the measure of ferritin itself specifically reflects iron stores, rather than measuring hemoglobin levels, vitamin B12 levels, or oxygen levels in the blood, which are evaluated through different tests. This specificity emphasizes the importance of ferritin in understanding and monitoring an individual's iron status.