Functional Iron Deficiency And Anemia

Every cell of your body requires oxygen. The oxygen taken into your lungs when you breathe crosses into your bloodstream and binds to an iron-containing protein called hemoglobin in your red blood cells. Anemia is the medical condition characterized by a low red blood cell count, or an inadequate level of hemoglobin. Functional iron deficiency is one of the many causes of anemia.

Iron and Red Blood Cell Production

Red blood cells live in your bloodstream for approximately four months. Your bone marrow continuously produces new red blood cells to replace those that have aged out of circulation. Iron availability affects your rate of red blood cell production because the mineral is an essential component of hemoglobin.

Absolute vs. Functional Iron-deficiency Anemia

Iron-deficiency anemia occurs when the total amount of iron in your body is abnormally low, typically due to iron loss from bleeding or an iron-poor diet. Health care professionals refer to this circumstance as absolute iron deficiency to distinguish it from functional iron deficiency. With functional iron deficiency, your body has a normal level of iron but it is largely unavailable to your bone marrow for red blood cell production. Without access to your iron stores, red blood cell production in your bone marrow slows, leading to anemia.

Who is Affected?

Functional iron-deficiency anemia typically occurs in people with chronic diseases, including chronic kidney disease, Crohn's disease, ulcerative colitis, cirrhosis of the liver, chronic viral hepatitis, HIV/AIDS, systemic lupus erythematosus and rheumatoid arthritis. Blood cell cancers such as lymphoma and Hodgkin's disease can also cause functional iron-deficiency anemia, also known as anemia of chronic disease.

Diagnosis

Your doctor uses blood tests to distinguish between absolute and functional iron-deficiency anemia. Although a low blood iron concentration occurs with both conditions, ferritin levels differ. Ferritin is a protein that binds stored iron. With an absolute iron deficiency, your ferritin level is abnormally low. With functional iron deficiency, however, your ferritin level is abnormally high, reflecting the imbalance between stored versus functionally available iron. If your diagnosis is unclear, your doctor may recommend a bone marrow biopsy, which involves taking a small sample of tissue through a large needle. Microscopic examination of the tissue in the laboratory typically leads to a definitive diagnosis.

Warning

You should not take iron supplements if you have functional iron-deficiency anemia unless your doctor advises you to do so. Because your body already has an adequate amount of iron with this condition, taking supplements could lead to iron overload, which can damage your liver. Your doctor will work with you to treat your anemia. Medical management typically focuses on treating the underlying chronic disease that has caused your functional iron deficiency.