Haemochromatosis

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Overview

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 removal of the excess iron, there is a gradual build-up of the excess iron in tissues and organs. This can lead to organ disease and failure. The symptoms of hereditary haemochromatosis occur in adults; early symptoms include tiredness and generally not feeling well.  As it gets worse, 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 (white skinned people) 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.  Between 1 in 200 and 1 in 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. Not all people with two mutated copies of the HH gene go on to develop iron overload and other symptoms of the disease, and research is currently being undertaken to establish what percentage of patients will go on to develop the full-blown disease and the reasons why.

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 the amount of iron it has stored. Confirmatory tests can include a genetic test and a liver biopsy. The latter can be used to find out if damage to liver tissue called fibrosis or cirrhosis has occurred. In addition, specialised radiological and MRI (Magnetic Resonance Imaging) tests have been developed to look at the levels of iron in the heart and liver.

Treatment of hereditary haemochromatosis consists of removing a pint of blood from the patient at frequent intervals since blood is rich in iron and this will reduce body iron stores. The frequency and length of treatment depend on the degree of iron overload. Once iron levels have returned to normal, blood can be removed at longer intervals.

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 who are at risk. Most affected individuals will have two copies of a 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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