Intracellular iron is stored in two compounds, ferritin and haemosiderin. Apoferritine (ferritin without iron) has a GM of 440 kD. A single molecule of apoferritine can keep ~ 4500 iron atoms, GM surpassing in this case 800 kD, but usually there are ferritin molecules with no more than 2000 iron atoms . Iron enters the molecule in the form of Fe2 + and is oxidized under the catalytic action of apoferritine( H chains have a ferroxidazic center) and is stored as a trivalent polymer of ferric hydroxide phosphate, the protein coating protecting the cell from the toxic effects of iron ions.
Apoferritine synthesis is stimulated by exposure to iron. There are at least 20 distinct isoferritine proteins with varying proportions of H and L chains. Ferritin is found in small quantities in plasma and its concentration correlates with iron deposits. Serum ferritin is glycosylated and relatively low in iron. In iron deficiency, ferritin decreases before the appearance of anemia / other hematological changes.
Recommendations for determination of ferritin:
– Differential diagnosis of anemia;
– Evaluation of iron deficiency anemia and iron replacement therapy monitoring (end point is the fill up iron deposits) and compliance to treatment;
– Monitoring categories of patients at risk for iron deficiency (detection of latent iron deficiency): pregnant women, blood donors, toddlers, hemodialysis patients, etc.
– Monitoring iron status in patients with chronic kidney disease, dialysis /non- dialysis.
– Diagnosis and monitoring of the depletion treatment in syndromes of iron overload.
Values: 12 -400 mg / L
Increases: > 400 mg / L
• Iron overload – a normal serum ferritin suggest that clinically significant iron overload is unlikely.
In hereditary hemochromatosis serum iron and transferrin saturation increase before ferritin (even in the presence of increased iron content in the liver). Increased ferritin is an indication of liver biopsy.
In secondary iron overload syndromes (transfusions, ineffective erythropoiesis, hemodialysis etc.) ferritin is always high.
– Liver disease (cirrhosis, hepatocellular carcinoma), leukemia, lymphoma, pancreatic cancer / bronchial, neuroblastoma (there is a relationship between the severity /extent of metastasis damage and ferritin level).
– Infectious diseases, inflammation, tumor, hyperthyroidism, MI – no quantitative relationship with iron stores (acute phase reactant).
– Megaloblastic anemia, hemolytic anemia, sideroblastic, thalassemia.
-Late cutaneous porphyria.
Ferritin has no value in assessing iron deposits in the presence of liver diseases.
Although not always show a linear relationship with deposits of iron, ferritin is the best parameter for measuring serum iron deposits. In uncomplicated iron deficiency anemia, ferritin is <12μg / L. When concomitant infectious disease / inflammation, serum ferritin is higher, but generally <50-60 mg / L. Always mean low serum ferritin iron deficiency (latent / overt), but the sensitivity of the test is low, since a normal value does not exclude iron deficiency.