Ferritin is a protein that stores iron in the body and serves as the primary indicator of total body iron stores. This test measures ferritin levels in the blood to evaluate iron status and diagnose various iron-related disorders. Low ferritin levels indicate iron deficiency, which can lead to iron deficiency anemia characterized by small, pale red blood cells. High ferritin levels can indicate iron overload conditions like hemochromatosis, or can be elevated due to inflammation, infection, liver disease, or certain cancers. Ferritin is particularly useful because it decreases before other iron tests show abnormalities, making it an early marker of iron deficiency. This test is commonly ordered when evaluating anemia, monitoring iron therapy, or when iron overload is suspected. Understanding ferritin levels is crucial for proper diagnosis and treatment of iron disorders, as both deficiency and excess can cause serious health problems.