Iron Studies
last authored: Jun 2009, David LaPierre
last reviewed:
Introduction
Peripheral smear can show target cells, pencil cells, or increased platelets if severe.
Serum Iron
Serum iron is a direct measure of iron bound to transferrin in the blood. Normally, SI is between 50-150 µg/dL.
Total Iron Binding Capacity
The TIBC is a measure of iron that can be bound in the blood. Normal TIBC is 300-360 µg/dL. SI / TIBC yields percent saturation, which is normally between 20-50%. When below 20% erothropoiesis is affected, while above 50% iron is loaded into tissues including hepatocytes, cardiac muscle, skin, and the pituitary gland.
TIBC is decreased in inflammation and increased in iron deficiency.
Serum ferritin levels
Serum ferritin levels estimate iron stores, and a low ferritin suggests iron deficiency.Each microgram of serum ferritin corresponding to 10 mg of tissue stores.
Children and menstruating women normally have ferritin levels of 20-50 ug/L, while men and postmenopausal women have levels of 50-200 ug/L.
Ferritin is increased in newborns, infections, inflammatory diease, and liver disease. As kids are often battling infection, ferritin is a very poor screening tool in children.
Serum-transferrin receptor
Levels of TfR increase rapidly once stores are depleted in proprtion to severity of anemia.
Patients with anemias characterized by increased reticulocyte number show increased [TfR], but patients with inflammation-induced anemia do not.
Marrow Iron Stores
A bit intense..
Red Blood Cell Protoporphyrin
Red blood cell protoporphyrin is a early measure of iron-deficient erythropoiesis and is very good for use in children due to the tiny amounts of blood required.
Zince protoporphyrin (ZPP) is an excellent screening tool where available.
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