Iron Disorder Hemosiderosis

Hemosiderosis is the medical term for iron overload, a condition that occurs when the body stores too much iron in organ tissues due to a lack of properly functioning red blood cells. Iron overload can damage organ tissue and cause serious health complications.

Genetic hemosiderosis is the term used to refer to iron overload caused by inherited genetic mutations. Other forms of iron overload, such as transfusional siderosis, are caused by external factors.

Genetic Hemosiderosis Types: Bantu Siderosis

Bantu siderosis, or African iron overload is, as the name implies, a type of hemosiderosis found mostly in Africa. Bantu siderosis affects up to ten percent of the population in some rural African communities.

Like other forms of genetic hemosiderosis, Bantu siderosis causes organ damage. Bantu siderosis is often associated with liver cirrhosis, and appears to be linked to higher than normal rates of infection and tuberculosis. Heart disease and diabetes may also result from iron overload, but they’re less common complications than cirrhosis.

Bantu siderosis appears to be a genetic hemosiderosis, but the genetic mutation causing African iron overload has yet to be determined. Doctors know that individuals with Bantu siderosis lack the HFE gene mutations associated with the most common genetic iron overload disorder, hemochromatosis.

The genetic marker that causes Bantu siderosis increases the risk of iron overload, especially when excessive dietary iron is consumed. The cause of Bantu siderosis was once thought to be over consumption of a traditional African beer made in non-galvanized steel drums.

Not all beer drinkers show symptoms of African iron overload, however, and cases of Bantu siderosis also occur in non-beer drinkers. This led researchers to conclude that Bantu siderosis was a genetic hemosiderosis.

Iron overload without the genetic markers for hemochromatosis can occur in African Americans. This has led to speculation that the genetic markers responsible for Bantu siderosis may be present in the African American population.

Ferroportin Disease

Ferroportin disease is the most common genetic hemosiderosis disease that does not involve the HFE mutations associated with hemochromatosis. Ferroportin disease is similar in nature to Bantu siderosis. Iron overload due to ferroportin disease is caused by mutations in the gene responsible for ferroportin production, a protein that exports iron from body cells.

Pulmonary Hemosiderosis

Pulmonary hemosiderosis occurs when repeated episodes of bleeding in the lungs causes an abnormal buildup of iron in lung tissue. This localized iron overload results in pulmonary fibrosis (scarring of the lungs), anemia and, in rare occasions, death due to pulmonary hemorrhage.

Pulmonary hemosiderosis can occur as a secondary complication of cardiovascular disease or as a systemic disorder. Children are most likely to experience pulmonary hemosiderosis as a primary condition.

Pulmonary hemosiderosis can occur at any age, but usually develops in children between the ages of one and seven. Symptoms of pulmonary iron overload include coughing up blood, iron deficiency anemia and physical changes to lung tissue.

Renal Hemosiderosis and Organ-Specific Iron Overload

Just as pulmonary hemosiderosis describes iron overload in the lungs, renal hemosiderosis indicates damaging iron overload in the the kidneys.

Renal hemosiderosis can occur due to hemolysis, the rapid destruction of red blood cells and the release of iron rich hemoglobin. As iron and hemoglobin collect in renal tissue, the urine may turn red, brown or tea-colored.

The liver is another likely site for organ-specific iron overload. Hepatic hemosiderosis (liver iron overload) occurs when abnormal iron levels accumulate in the liver.

Transfusional Siderosis

Transfusional siderosis is caused by artificial means, and is not one of the genetic hemosiderosis varieties. Transfusional siderosis is triggered by frequent blood transfusions.

Repeated blood transfusions are life-saving treatments for a number of conditions that cause severe anemia, such as thalassemia and bone marrow failure. Chemotherapy patients may require regular blood transfusions, and transfusions are also effective treatment for life-threatening sickle cell anemia complications.

Blood transfusions are often used to treat low blood iron levels associated with anemia. However, as each unit of blood contains between 200 and 300 milligrams of iron, repeated transfusions of blood can rapidly cause iron overload and transfusional hemosiderosis.

The underlying conditions associated with transfusional siderosis make phlebotomy (regular blood drawing to reduce iron overload) an impractical treatment. Instead, transfusional iron overload is treated with chelation therapy, which uses synthetic compounds and body proteins to extract iron from the blood.

Resources

Andrews, N. C. (1999, December 23). Disorders of iron metabolism. The New England Journal of Medicine 341(26), 1986-1995.

Beers, M. H.