Ferritin

Ferritin is a protein that stores iron inside your cells and releases it in a controlled way when your body needs it. A ferritin blood test estimates how much iron is stored in your body, which is different from measuring iron circulating in the bloodstream. It is usually measured on a serum or plasma sample as part of an iron studies panel.

Ferritin is also an acute phase reactant, which means its level can rise when you have inflammation, infection, or liver injury. Because of this, ferritin reflects both iron stores and your overall health context, and it is interpreted alongside other tests and your symptoms.

Ferritin helps your clinician check for iron deficiency, a common cause of fatigue, hair loss, shortness of breath, and anemia. It is also used to monitor your response to iron therapy and to investigate causes of blood loss, such as heavy menstrual bleeding or gastrointestinal bleeding.

High ferritin can point to inflammation, liver disease, metabolic conditions, chronic kidney disease, or inherited iron overload. Because ferritin can change with illness and medication use, your clinician often orders it with other iron tests and a complete blood count to guide diagnosis and treatment.

Lower ferritin generally suggests that iron stores are reduced, which can occur with inadequate intake, increased needs, or ongoing blood loss. If your ferritin is low, your clinician may look for causes, review your diet, and consider iron replacement while monitoring for side effects and response.

Higher ferritin does not always mean too much iron. It can increase when your body is fighting an infection, when there is inflammation, with liver problems, or in certain metabolic or blood conditions. Your clinician may review your history, examine you, and order additional tests such as serum iron, transferrin saturation, inflammatory markers, and liver tests to clarify the cause. Do not start or stop iron supplements without medical advice, and ask how your results fit with your overall health.