Serum ferritin is the first line initial test for iron deficiency because iron deficiency is the only cause of low ferritin.
Absolute iron deficiency reveals ferritin levels typically less than 30 ng per mL which has a 98% specitivity and a 72% sensitivity for absolute bone marrow iron stores.
The sensitivity of ferritin for diagnosing iron deficiency is reduced in inflammatory conditions because ferritin is an acute phase reactant and increases with inflammation so with iron deficiency and concurrent inflammatory conditions, ferritin levels rarely exceed 100 ng per mL.
Serum ferritin is the most common used estimate of body iron stores and reflects only 1% of the total iron storage pool.
Serum ferritin grossly proportional to total body iron load in large population studies.
Reliance on serum ferritin alone can lead to inaccurate estimates of body iron stores in individual patients.
Normal ferritin levels range from: 24 to 336 micrograms per liter for men; 11 to 307 micrograms per liter for women.
High serum levels in renal insufficiency reflect the malnutrition inflammation complex syndrome and is a marker for morbidity and mortality in dialysis patients.
Acute phase reactant and elevated in inflammatory states, infection, liver disease and malignancy.
Serum levels are about 25 ng/mL in children and in premenopausal women, but increase in menopausal women corresponding to increased risk of myocardial infarction with cessation of menstrual blood loss.
Overload is defined as serum ferritin levels consistenly at 1,000 ug/L or higher.
Iron release from senescent RBCs can be stored as ferritin or exported into the circulation.
Ferritin is and iron storage protein complex composed of ferritin monomers of 2 subtypes: heavy and light chains.
Heavy chain ferritin has ferroxidase activity, that is needed for oxidation of incoming ferritous ions.
Lght chain ferritin promotes nucleation and mineralization.