طب الجهاز الهضمي والكبد

The Hereditary Hemochromatosis Clinic at Mayo Clinic's campus in Florida provides screening, genetic testing and treatment.

Overview

The Hereditary Hemochromatosis Clinic located on Mayo Clinic's campus in Florida provides state-of-the-art diagnostics, treatments and education to patients who have hereditary hemochromatosis or who are at risk of developing it.

Hereditary hemochromatosis is an inherited disease that makes your body absorb more iron than it needs, leading to iron overload. Over time, excess iron can interfere with function of the liver, heart, pancreas and reproductive glands (ovaries in women and testicles in men). Untreated hereditary hemochromatosis can have serious complications, including cirrhosis, liver cancer and heart failure.

The Hereditary Hemochromatosis Clinic provides the following services in one center, where testing and initial treatment can take place over the course of a one- or two-day visit.

Diagnosis

The signs and symptoms of iron overload due to hereditary hemochromatosis take many years to develop. Through childhood and adolescence, normal growth counterbalances excess iron absorption, sparing the organs where iron builds up. In adulthood, though, iron starts to accumulate in these organs year by year. As iron levels rise over the adult years, the likelihood of signs and symptoms such as fatigue, joint pain, swollen legs and loss of sex drive also rises.

Today, because of increased awareness of family medical history and wider availability of genetic testing, hereditary hemochromatosis is usually diagnosed before the condition causes symptoms. Even when there is no known family history of iron overload, tests done in the course of regular medical care sometimes lead to the diagnosis. More commonly, doctors make the diagnosis in people with parents or siblings (first-degree relatives) who have hereditary hemochromatosis.

Patients in both groups find their way to the Hereditary Hemochromatosis Clinic for a detailed diagnostic workup consisting of these steps:

• Screening blood test. This blood test provides two measurements of iron overload — specifically, how much iron your body has stored (serum ferritin) and how much of your iron-storage capacity is available (serum transferrin saturation). Together, these measurements identify the majority of people with hereditary hemochromatosis.

• Genetic test panel. An additional blood test confirms the result of the screening test and identifies the genetic mutation responsible for an individual case of hemochromatosis. People with hereditary hemochromatosis have an inherited mutation in a gene that holds the code for a protein with a vital role in iron absorption and storage. The most common type of the disease affects people who have a particular mutation (C282Y) on both copies of this gene, meaning one copy came from their mother and one from their father. A few people have a combination of mutations, such as one copy of the gene with the C282Y mutation and another with a less common mutation. Still others inherit only one copy of the gene.

  Knowing which mutation is responsible for the condition is helpful in treating hereditary hemochromatosis and in screening family members who may also be affected. The advanced genetics laboratory at Mayo Clinic's campus in Florida has experience detecting unusual mutations that produce different types of hereditary hemochromatosis — not just the most common type.

• Metabolic testing. Many people with hemochromatosis are insulin resistant, which means their bodies produce the hormone insulin but don't use it effectively to control blood glucose. Insulin resistance can progress to type 2 diabetes. Patients at the Hereditary Hemochromatosis Clinic in Florida are tested for these conditions, as well as for other hormonal abnormalities.

• Staging. Whenever possible, physicians at the Hereditary Hemochromatosis Clinic in Florida use painless, noninvasive imaging tests to assess the liver damage caused by iron overload. One such test, magnetic resonance elastography, combines magnetic resonance imaging with vibrational waves directed at the liver to produce a map showing the relative stiffness of tissue throughout the liver. Another test, transient elastography, is based on ultrasound. Both tests quantify the amount of scarring (fibrosis) in the liver, which corresponds with the severity of liver disease.

  In some cases, a liver biopsy is necessary for accurate diagnosis. Liver biopsy is an outpatient procedure in which a doctor, using ultrasound guidance, inserts a needle through the abdominal wall to the liver and takes out a sliver of tissue for laboratory analysis.

Ongoing treatment and monitoring

The initial treatment for hereditary hemochromatosis is weekly removal of a pint of blood (therapeutic phlebotomy) until iron levels begin to decrease. When blood tests show that your ferritin is in the target range, you can switch to a less frequent schedule for therapeutic phlebotomy.

At the Hereditary Hemochromatosis Clinic in Florida, a complete blood count is done at the time of each treatment. If the blood count shows that you are losing too much blood or if you have an abnormal blood count before starting therapeutic phlebotomy, treatment with medication is an option. Drugs called iron chelators, taken orally, are effective at removing excess iron. Because iron chelators can have serious side effects, therapeutic phlebotomy is the first line treatment.

Lifestyle support

Other services available to patients at the Hereditary Hemochromatosis Clinic in Florida include:

• Nutrition education. People with hereditary hemochromatosis should limit supplemental iron and vitamin C in their diets. At the Hereditary Hemochromatosis Clinic, certified dietitians help patients understand their dietary needs.
• Genetic counseling. At the Hereditary Hemochromatosis Clinic, people with hereditary hemochromatosis receive genetic counseling to understand the risk the condition could pose to their offspring. Immediate family members of patients can also seek genetic testing to find out if they also have hereditary hemochromatosis or if they carry the mutation that could put their children at risk.