- Causes and risk factors
- Examinations and diagnosis
- Disease course and prognosis
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.
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.To the table of contents
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.
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.
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.
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.
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.
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.To the table of contents
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.
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.
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.To the table of contents
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: