hemochromatosis

Hemochromatosis: description

Hemochromatosis is an iron-storing disease: a balance between iron uptake and excretion leads to an iron overload of the tissue. Especially dangerous are deposits in the liver and the heart muscle, but also in the pancreas, skin or pituitary gland.

Hemochromatosis can be genetic and is called primary or hereditary. This should be distinguished from secondary hemochromatosis. It is acquired by another underlying disease. For example, too many blood transfusions in case of anemia (anemia) can lead to an iron overload in the body.

The term hemosiderosis is sometimes used as a synonym for hemochromatosis or regarded as a kind of precursor thereof. It is derived from hemosiderin – an iron-containing protein complex. Iron can be stored in the body in the form of hemosiderin, especially in special immune cells, the macrophages. Hemosiderosis can also occur only locally, for example on the lower legs.

Occurrence

Hereditary hemochromatosis is the most common genetic disease in Northern Europe. Overall, hemochromatosis is found in one to five out of every 1,000 people. The disease accounts for up to two percent of new cases of diabetes mellitus and up to 15 percent of all liver cirrhosis. Primary hemochromatosis affects men ten times more often than women because they regularly lose blood and therefore iron during the menstrual cycle.

The iron metabolism

Iron is essential for the human body. It plays a crucial role in the production of red blood cells as well as the survival and growth of cells. The iron balance must therefore be controlled by the body as needed to prevent iron deficiency or overcharging.

In healthy people, intake and excretion of iron are balanced. The body needs 25 milligrams a day, especially to develop red blood cells in the bone marrow. The majority of the iron needed comes from the recycling of degraded blood cells. The remaining need is covered by iron-containing food. Healthy people absorb about ten percent of iron in the intestine. This equates to between one and two milligrams per day. However, genetically-induced hemochromatosis will consume up to 20 percent of the nutritional iron.

The crucial step of iron uptake is the transfer of iron from the intestinal cell into the blood, which is controlled by, among other things, the protein hepcidin. In the blood, iron is transported bound to the protein transferrin.

The main part of the body iron is stored in the red blood cells (hemoglobin), liver and immune cells (reticuloendothelial system) – for example in the form of ferritin (an iron-protein complex), which can be detected in the blood. Usually, the body stores one to four grams of iron – in hemochromatosis, however, more than twice the amount. This burdens the affected organs very much and can lead to serious complications.

Hemochromatosis: symptoms

The first obvious signs of hemochromatosis appear mostly between the ages of 40 and 60, often earlier in men than in women. However, there are also forms of hemochromatosis in which liver damage develops before birth (neonatal hemochromatosis). In addition, there are also juvenile forms of hemochromatosis, which shows up before the 30th year of life. This juvenile hemochromatosis is mainly characterized by heart failure and hypofunction of the gonads.

The classic three iron trapping symptoms are Diabetes mellitus, liver damage and skin pigmentation, These are but late damage. They have become rarer now, because the disease is now mostly discovered earlier. In the early phase of hemochromatosis, unspecific symptoms such as tiredness, abdominal pain, and joint discomfort are particularly evident.

joints

Up to 80 percent of those affected complain of severe joint problems that often start years before the diagnosis. Typically, the joints of the middle and index fingers are affected in both hands, but also knee and hip joints. The joint problems worsen in the course of the disease and can be either inflammatory or non-inflammatory nature.

liver

The liver is one of the main stores of iron in the body and also the first organ that is reached by the blood after it has passed through the intestine. An iron overload over a longer period leads to a connective tissue remodeling of the liver and the downfall of liver tissue (liver cirrhosis). The typical symptoms are loss of power, loss of appetite, weight loss and feeling of fullness. Yellowing of the skin and eyes and other skin symptoms such as spider nävi, redness and itching do not occur until late stages.

Around 30 percent of hemochromatosis cases with cirrhosis of the liver develop into a malignant liver tumor (hepatocellular carcinoma). This increases the risk of liver cancer in this constellation by a factor of 100. Other liver diseases, such as liver inflammation, can increase the progress of liver damage.

skin

The skin may turn dark, especially in the armpit. This is due to the fact that melanin (the dark pigment) is increasingly stored in the skin. This is called Bronzediabetes. The skin hair, especially in the armpit, thin out.

pancreas

The pancreas is also burdened by excess iron in hemochromatosis. First, the body cells no longer respond to the blood sugar-lowering hormone insulin (insulin resistance). Later, the insulin cells are so damaged by the iron that they can no longer produce enough insulin. This causes diabetes mellitus.

heart

In young patients, heart damage is a common cause of death due to hemochromatosis. Iron deposits in the heart lead to muscle damage (cardiomyopathy) and cardiac arrhythmias. This can result in heart failure and failure with mortal danger. If heart muscle damage occurs during hemochromatosis, transplantation may be required.

Hormone system (endocrine)

The various hormonal systems of the body can be affected to varying degrees by hemochromatosis. Typical is a hypofunction of the sex glands, the thyroid gland and the adrenal cortex. Men can become impotent.

Hemochromatosis: causes and risk factors

The iron overload is usually due to a dysregulation of iron intake, a disturbed blood formation or increased iron intake, especially by transfusion (in anemia = anemia). Long-term intravenous or intramuscular iron intake can also lead to overcharging. The body can no longer store that much iron in a stable form. It then unfolds a toxic effect on the tissue.

Primary hemochromatosis

Congenital gene mutations of the iron metabolism regulating proteins are the most common cause of hemochromatosis in Germany. There are several forms of genetic hemochromatosis. In Germany, almost only type 1 occurs, a gene mutation on chromosome 6 that affects the HFE gene. The HFE protein encoded by this gene inhibits iron uptake in the gut. It is thought to bind to and block the transferrin receptor on the cells. Transferrin is the transport protein for iron in the blood. If it can no longer bind to its receptor, it promotes the release of hepcidin. This protein in turn inhibits iron absorption from the intestine. If the HFE protein fails, this iron-absorption brake is missing. As a result, too much iron is absorbed in the intestine. However, it usually takes decades before it results in organ damage.

Secondary hemochromatosis

In the so-called secondary forms of hemochromatosis, there is usually an iron overload of the cells of the reticuloendothelial system, ie cells of the immune system, but also of other organs. The most common cause is a congenital or acquired malfunction of blood formation, which is usually associated with anemia. On the one hand, this increases the body’s iron intake via the intestine. On the other hand, blood transfusions must be given repeatedly in case of severe anemia. This artificially adds a lot of iron to the body. For example, a year’s iron intake in the form of tablets may rarely be responsible for haemochromatosis.

Also a malformation of the red blood pigment (thalassemia) and an abnormal deformability of the red blood cells (sickle cell anemia) can cause a secondary hemochromatosis. Both are genetic diseases.

Acquired diseases that can cause hemochromatosis include myelodysplastic syndrome (a disorder in bone marrow formation) and myelofibrosis (connective tissue remodeling of the bone marrow). Both diseases have in common that the turnover of the (red) blood cells and thus of the iron is significantly increased.

Hemochromatosis: examinations and diagnosis

Patients usually do not notice anything about hemochromatosis in their early stages. Early signs such as joint problems or tiredness are nonspecific. In most cases, hemochromatosis is therefore either discovered by chance in blood tests that give evidence of an iron deficiency disorder. Or the diagnosis of iron storage disease is made through systematic screening (by family members) for abnormalities.

To clarify a hemochromatosis, the doctor will first raise the medical history (anamnesis). In conversation with the patient, he will ask questions such as:

• Were previous blood tests conspicuous?
• Are iron-storage disorders known in your family?
• Do you suffer from joint pain or tiredness?
• Do you have stomach or heart problems?

Physical examination

During the physical examination, the doctor pays particular attention to signs of damage to the heart and liver as well as increased pigmentation of the skin (Bronzediabetes). Joint complaints on the index and middle fingers are also typical for hemochromatosis.

Laboratory values ​​in the blood

The aim of the blood tests is the assessment of the iron balance. The three most important parameters in hemochromatosis diagnosis are serum iron levels, ferritin and transferrin saturation. The blood sample should be taken sober in the morning.

Increased iron concentrations in the blood strengthen the suspicion of hemochromatosis. However, even with normal iron levels an iron storage disease can not be safely ruled out.

The protein ferritin gives better information about the iron content in the body. Ferritin is the storage whiteness of iron. Low levels indicate iron deficiency. Elevated levels indicate an increased iron storage. However, high levels of ferritin are also explainable by inflammation and malignant diseases. For this reason, the ferritin value is not evaluable, if at the same time the inflammatory parameters are increased.

Ferritin is important not only for diagnosis but also to assess the success of hemochromatosis therapy.

The third important iron parameter m blood is the Transferrin saturation, In the blood, most of the iron is bound to transferrin. For this reason, you measure how much of the transferrin is loaded with iron. Transferrin saturation above 45% is suspected to be due to hemochromatosis. At a saturation of more than 60 percent, the suspicion is even very strong. Normal transferrin saturation virtually eliminates hemochromatosis.

If a patient has both an increased ferritin concentration and a high transferrin saturation, the suspicion of an iron storage disease is near. To confirm it, a genetic test should be performed.

Genetic test

In the case of conspicuous iron blood values, the next step is a genetic examination. First, it is tested whether a mutation of the HFE gene (C2828Y) is present. Every human being has two copies of this gene, one each from mother and father. Only if both copies are damaged by a mutation (homozygous carriers of the gene mutation), the diagnosis hemochromatosis is secured, and it can be dispensed with the removal of a tissue sample from the liver (liver biopsy).

If only one copy of the gene is damaged (heterozygous carriers), those affected remain mostly healthy but should be examined regularly. However, if such heterozygous carriers show symptoms of hemochromatosis or liver damage, either a liver biopsy or another genetic test should be performed. If biopsy indicates evidence of iron storage disease, other known mutations in iron metabolism can be sought.

Genetic forms of hemochromatosis should include family members for hemochromatosis.

liver tests

By taking a small piece of tissue from the liver (biopsy), the condition of the liver and its iron content (Berliner-Blau reaction) can be randomly checked. The iron content can be given as a liver iron concentration or as a liver iron index. The latter arises when one divides the liver iron concentration by the age.

Today, the biopsy can be replaced by modern technical procedures that do not require tissue removal. Possible methods are liver ultrasonography and magnetic resonance imaging (MRI) of the liver. The liver absorbance makes use of the magnetic properties of iron. However, the process is very expensive and rarely used. With the help of MRI, the iron content can only be estimated at late stages

To check the function and condition of the liver, regular blood tests and ultrasound examinations must be performed. If the liver already has signs of cirrhosis, then the concentration of α-fetoprotein in the blood should also be determined as a marker for malignant degeneration of the liver tissue.

iron heart

Heart muscle damage and cardiac arrhythmias, which can lead to heart failure, are a possible cause of death in hemochromatosis. The heart function should therefore be checked with a special ultrasound examination (echocardiography) and an electrocardiogram (ECG). With a magnetic resonance examination, the iron content and the condition of the heart can be estimated.

endocrinology

At the time of initial diagnosis or indications of disorders of the endocrine system, appropriate examinations should be made. For example, suspected hypoglycemic, thyroid or adrenal cortex subunits should be measured to determine the levels of the corresponding hormones in the blood.

Hemochromatosis: treatment

The aim of hemochromatosis therapy is to reduce the iron load on the body to prevent the progression of hemochromatosis. There are two major therapies available:

• Bloodletting / Erythrozytapherese
• Iron chelators

Bloodletting therapy and erythrocytapheresis

Bloodletting therapy (phlebotomy) is mainly used for genetically induced hemochromatosis. For this purpose, about 500 milliliters of blood are removed from a vein at regular intervals. About 250 milligrams of iron can be removed from the body per bloodletting. Symptomatic hemochromatosis contains about 10 to 30 grams of iron in the body. In order to bring the iron storage back to normal level with an iron content of up to four grams, 40 to 120 bloodlettings over a period of one to two years are therefore necessary.

At the beginning the bloodletting is carried out once or twice a week. For follow-up, the blood concentrations of ferritin and the red blood pigment (hemoglobin) are regularly measured. Low hemoglobin indicates anemia. Then the therapy may need to be interrupted.

When the concentration of ferritin in the blood has normalized, four to eight annual bloodlettings suffice.

If family members of a patient with genetic hemochromatosis have elevated levels of ferritin, they may undergo preventive phlebotomy.

On the same principle as bloodletting is based Erythrozytapherese, In contrast to bloodletting, however, the extracted blood is mechanically separated here: only the red blood cells are removed and the remaining blood components are returned to the body. This method is used, among others, in patients with anemia due to red blood cell defects.

Iron chelators

Drug therapy of hemochromatosis is supposed to increase iron excretion via urine and stool. This is achieved with so-called chelating agents or chelators. These are substances that bind iron and are then eliminated with it. They are mainly given in hemochromatosis forms associated with anemia. Because bloodletting is not possible. Most therapy is started at high serum ferritin levels or a liver iron concentration above the threshold. It usually has to be continued for life. Only rarely does the blood levels of the iron balance normalize like ferritin.

When treating with chelating agents should Benefits and risks always be weighed carefully by new ones. The active ingredients are suspected to inhibit the growth of children. In adults, gastrointestinal symptoms, skin rashes and an increase in liver enzyme concentration in the blood are typical side effects. Also inner ear and visual disturbances, fever, headache and joint complaints can occur.

If therapy with iron chelators does not work well enough, if severe heart damage is present, or if there is another reason for rapid iron elimination, drug therapy may be intensified. Such Intensive treatment should be done in specialized centers. The chelating agents are then continuously injected under the skin or into the vein for 24 hours. Also a longer intensive dose over this way is possible.

pregnant woman should not be treated with chelating agents. From the fourth month of pregnancy, however, the therapy may possibly (under strict consideration) be taken up again. In this case, close-up examinations of the pregnant women are absolutely necessary. Pregnant women with hemochromatosis should seek advice in specialized centers.

What brings an iron diet?

A strict iron-poor diet is very difficult to maintain and only slightly effective. For this reason, no special haemochromatosis diet is recommended. Recommended, however, is the renunciation of iron-rich foods such as offal. It should also be noted that coffee and tea can reduce the absorption of iron, while the consumption of alcohol, more iron is absorbed in the intestine. Red wines can also be rich in iron. Alcohol should therefore be avoided as much as possible. It is best to use black tea as a drink during meals to reduce iron intake from the diet. The intake of vitamin supplements is not recommended.

organ transplantation

In late stages of hemochromatosis with severe liver or heart damage, organ transplantation may be required and vital. Haemochromatosis (neonatal hemochromatosis), which has been in existence since birth, is the most common reason for liver transplantation during the first three months of life.

Hemochromatosis: disease course and prognosis

By measuring blood levels that reflect the iron balance, early detection of hemochromatosis has become possible. If the disease is detected and treated early – before late damage such as cirrhosis of the liver, cardiomyopathy or diabetes mellitus occur – sufferers have a normal life expectancy.

The prognosis is significantly worse if the hemochromatosis is detected late or not treated. Even if frequent blood transfusions are needed due to anemia, hemochromatosis can progress faster. Most feared are serious heart damage that can lead to (sudden) heart failure resulting in death. Regular monitoring of organ functions, especially of the heart and liver, is therefore essential.

Liver enlargement and elevations of liver enzymes are usually declining in a successful treatment of hemochromatosis. However, late effects such as diabetes mellitus or heart damage can hardly be improved by the treatment. The joint complaints and testicular hypofunction remain in spite of therapy. However, the treatment can relieve symptoms such as pain and fatigue and thus the quality of life hemochromatosisSignificantly increase the number of people affected.