Haemochromatosis, also called iron overload, can result from several medical conditions, the most common of which is an inherited disorder of iron metabolism that occurs mainly in white skinned people (Caucasians), termed hereditary haemochromatosis or HH.
Iron is absorbed from the diet through the small intestine, and the amount absorbed is determined by the body's needs. People with hereditary haemochromatosis absorb more iron than their body needs. As the body does not have a way to increase excretion of the excess iron, there is a progressive build-up of the excess iron in tissues and organs. This can lead to organ dysfunction and failure. The symptoms of hereditary haemochromatosis occur in adults; early symptoms include fatigue and a loss of well-being. As it progresses, complications can include arthritis, diabetes, liver cirrhosis, heart arrhythmias and failure, loss of libido, and an increase in skin pigmentation termed "bronzing."
Approximately 1 in 10 Caucasians have one abnormal (or mutated) copy of the gene associated with hereditary haemochromatosis and are referred to as carriers. Carriers are not at particular risk for developing iron overload. Approximately 1 in 200 to 400 Caucasians have two abnormal (or mutated) copies of the gene associated with HH and are at risk for developing iron overload and clinical symptoms. Research is going on to determine what percentage of individuals with two abnormal gene copies develop iron overload and clinical symptoms.
Laboratory investigation for hereditary haemochromatosis usually begins with two blood tests: transferrin saturation and serum ferritin, which are measures of the body's iron metabolism and iron stores. Confirmatory tests can include genetic testing and liver biopsy. The latter can be used to determine if damage to liver tissue called fibrosis or cirrhosis has occurred.
Treatment of hereditary haemochromatosis consists of withdrawing a pint of blood at frequent intervals to reduce body iron stores. The frequency and length of treatment depend on the degree of iron overload. Once iron levels are normalised, pints of blood are then withdrawn at longer intervals to avoid reaccumulation.
Genetic tests for haemochromatosis
Nearly all people with haemochromatosis will carry identifiable variants in the HFE gene, confirmed by a blood test, which can then be used in identifying family members at risk. Most affected individuals will have two copies of the variant called C282Y. Some will have one copy of C282Y and one called H63D. People with two copies of H63D do not seem to be at particular risk of iron overload themselves.
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