What Is Haemosiderosis?

Haemosiderosis 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 haemosiderosis 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.

Transfusional siderosis is caused by artificial means, and is not one of the genetic haemosiderosis 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 haemosiderosis.

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.

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

Like other forms of genetic haemosiderosis, 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 haemosiderosis, 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, haemochromatosis.

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 haemosiderosis.

Iron overload without the genetic markers for haemochromatosis 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 is the most common genetic haemosiderosis disease that does not involve the HFE mutations associated with haemochromatosis. 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.

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

Renal haemosiderosis can occur due to haemolysis, the rapid destruction of red blood cells and the release of iron rich haemoglobin. As iron and haemoglobin 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 haemosiderosis (liver iron overload) occurs when abnormal iron levels accumulate in the liver.

Pulmonary Haemosiderosis