Hemochromatosis

(Iron Overload, Hereditary Hemochromatosis)

In this condition factsheet:

• The Facts
• Causes
• Symptoms and Complications
• Making the Diagnosis
• Treatment and Prevention

The Facts

Hemochromatosis is primarily an inherited (genetic) condition that allows too much iron to be absorbed and stored throughout the body. It's one of the most common genetic disorders in Canada.

1 in 9 Canadians carries the defective gene for this condition, and 1 in 300 Canadians is affected with the condition. Men and women are equally affected, although signs appear later in women.

Most people absorb only enough iron to meet their body's daily requirements, and the excess is excreted. In hemochromatosis, however, iron continues to be absorbed and stored in different organs and tissues long after the body's needs are met.

The liver is the first organ to store excess iron, after which it accumulates in the heart, pituitary gland, and elsewhere in the body. Left untreated, the resulting damage to the liver, heart, and pancreas may eventually lead to death.

In hemochromatosis, the total iron content in the body can reach as high as 50 grams, compared with the normal levels of about 2.5 grams in women and 3.5 grams in men. It's been nicknamed "bronze diabetes" because it may be accompanied by diabetes mellitus and increased skin pigmentation (darkening of the skin).

Because women lose iron in their menstrual flow, they tend to be protected from getting hemochromatosis as long as they are having menstrual cycles. Thus it affects men earlier than women, usually when men are between 40 and 60 years of age. Rare cases have occurred in children.

Causes

Hemochromatosis is usually hereditary. It takes two defective copies of the same gene, with one defective copy inherited from each parent, to cause hemochromatosis. Siblings of those affected have a 25% chance of getting it. Both parents must be carriers of the defective gene, which means that a child of a person with hemochromatosis is less likely to have it than are the person's siblings.

However, hemochromatosis may also be caused by multiple blood transfusions and certain liver diseases, especially cirrhosis. Chronic hepatitis C infection can also result in an increased storage of iron, although a genetic cause should always be ruled out first.

Symptoms and Complications

Many people with hemochromatosis don't have any noticeable symptoms. The liver will begin to retain iron at birth, but it may take 20 to 30 years before symptoms appear. Early symptoms include fatigue and swelling in the joints (arthritis), particularly in the knuckles of the middle and index fingers.

In the later stages of the disease, people may experience:

• abdominal pain or tenderness
• abdominal swelling
• bleeding from dilated veins in the esophagus
• bronze- or grey-coloured skin
• diabetes
• erectile difficulties
• excessive hunger and thirst
• frequent urination
• yellowing of the skin and eyes (jaundice)

If iron builds up in the heart muscle, it may cause irregular heartbeat and heart failure, leading to shortness of breath and swelling of the ankles. If it accumulates in the pituitary gland, it can cause menstrual irregularities in women and sexual dysfunction, loss of sex drive, and erectile difficulties in men.

Other specific organ-related symptoms may include joint pain, abdominal pain due to hepatic enlargement, and diabetes as a result of damage to the pancreas.

Men usually accumulate over 10 grams of iron in their body before symptoms develop. In women, symptoms often show up after menopause and about 5 to 10 years later than in men. This is because menstruation and pregnancy protect them from building up too much iron. Women who reach menopause before the age of 50 often have more iron in their bodies than those who reach it after age 50.

Complications due to hemochromatosis cause the most serious problems, which is why early detection and treatment are essential. Once the condition is advanced, arthritis, cirrhosis, bronze skin pigmentation, diabetes mellitus (occurring in 65% of people with hemochromatosis), heart problems, and heart failure may appear. Pituitary failure is common and may be the cause of testicular atrophy (shrinkage of the testicles) and loss of sex drive, which occurs frequently. Early detection and treatment before the liver is damaged usually allows the person with hemochromatosis to have a normal life expectancy.

If potential life-threatening complications have occurred – such as an enlarged liver or spleen, or heart problems – life expectancy can be increased by treating these complications. Damage caused by cirrhosis of the liver, however, is irreversible.

Making the Diagnosis

If a doctor suspects hemochromatosis, a physical examination is done to check for an enlarged liver, enlarged spleen, or skin colour changes. Blood tests are ordered to measure the iron level in the blood and the amount of iron deposited in tissues. The most common blood tests check the amount of iron, total iron binding capacity (protein), transferrin saturation, and serum ferritin.

A genetic blood test for hemochromatosis is available. The test is usually done in a lab specializing in DNA testing. In more than 95% of those with typical hemochromatosis, a specific gene mutation (C282Y or C282Y/H63D) is present.

A liver biopsy to confirm the diagnosis may also be necessary. A biopsy is done by inserting a thin needle into the liver and taking a tiny tissue sample that is then checked for damage or disease. The procedure is quite safe and usually has no complications. Occasionally there is some discomfort or bleeding after the procedure. People with liver disease should have their coagulation (blood clotting) levels checked and any abnormalities corrected prior to the biopsy to lessen the chance of bleeding.

Now that there is genetic testing for hereditary hemochromatosis, liver biopsies aren't always necessary in order to diagnose it.

Diagnosis of hemochromatosis may be delayed because symptoms don't usually appear until middle age. Even then, clinical symptoms may not be obvious, so hemochromatosis is often diagnosed after it has caused significant tissue damage. Since several organs may be affected, it usually takes some time to figure out the exact cause of the problem.

Other non-genetic causes of excess iron due to red cell breakdown, such as sickle cell anemia and thalassemia, should be ruled out, as well as other inherited disorders.

Treatment and Prevention

The good news is that hereditary hemochromatosis is treatable. The goal of treatment is quite simple: to remove excess iron from the body and to treat any damaged organs. Usually, the best treatment is to remove the excess iron by withdrawing blood (phlebotomy) – about a half-litre once or twice a week. This process is very similar to donating blood.

Phlebotomy should be started as soon as the person is diagnosed. This treatment may be required for 1 to 2 years until the iron level in the blood is normal. After that, blood won't have to be removed as often to maintain normal iron levels.

Because people build up iron at different rates, some may be able to go without regular maintenance phlebotomy for quite some time (perhaps 6 to 12 months). Medications that chelate (bind) the iron (e.g., deferoxamine*) and remove it from the body are only necessary in patients with heart problems caused by hemochromatosis and in those who can't have phlebotomy treatments because they have anemia.

Problems due to hemochromatosis are treated separately. For example, if a person has a reduced sex drive and a change in secondary sexual characteristics, such as atrophy of the testicles, testosterone therapy may be prescribed. Diabetes, arthritis, liver failure, and heart failure associated with hemochromatosis are treated as necessary.

All first-degree relatives (e.g., parents, siblings, or children) of a person with hemochromatosis should be screened for the condition. It's important to detect the disease early so that treatment can be started before organ damage occurs.

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