Amyloidosis is a term used to describe various rare diseases that cause abnormal protein deposits. These lead to a variety of organ damage. What causes the disease and how amyloidosis is treated.
- In the early stages, amyloidosis is often discovered only by chance.
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What is amyloidosis?
The term amyloidosis covers several rare diseases that have different causes. What they have in common is that certain proteins are mistakenly deposited as insoluble aggregates in the space between the cells of the body: the normally soluble proteins clump together to form insoluble fibers known as amyloids. As a result, they cause the organs to malfunction up to and including organ failure and death in the worst case. Amyloid deposits can occur systemically throughout the body or localized in only one organ or tissue.
So far, ten different proteins have been detected in amyloid deposits – the amyloidoses are classified according to the protein involved. In western industrialized countries, light chain amyloidosis (AL amyloidosis) is the most common form.
The formation of amyloids also takes place in diseases such as Alzheimer's or Creutzfeld-Jakob disease. Strictly speaking, these are therefore also amyloidoses.
Causes of Amyloidosis
Amyloidosis can occur at any age and affects both sexes equally. From the age of 85, so-called senile amyloid is found in every person, which can be viewed as a normal aging process.
There are basically two different causes of amyloidosis: On the one hand, genetic changes lead to errors in protein folding, and as a result the proteins are deposited as amyloids. On the other hand, certain diseases associated with chronic inflammation increase the serum level of amyloids.
These include:
Symptoms: how is amyloidosis manifested?
The first symptoms of amyloidosis are very unspecific, for example loss of appetite, weight loss, tiredness or decreased physical performance. In addition, the different types of amyloidosis cause different symptoms. Doctors often only discover early-stage amyloidosis by chance during a biopsy.
If, on the other hand, organ-specific symptoms occur, the organ function is already severely damaged or restricted by heavy deposits of amyloids.
Possible organ-specific symptoms of amyloidosis:
Respiratory tract: Difficulty breathing (dyspnea), wheezing, blocked airways (obstruction)
Skin: Often bruises, sometimes around the eyes ("raccoon eyes"), enlarged tongue (macroglossia)
Heart: cardiac arrhythmias and heart failure, which are manifested by weakness, shortness of breath or fainting
Liver: Enlarged liver (hepatomegaly), ascites (ascites)
Nerves: tingling, numbness in fingers and toes, dizziness on standing up
Kidneys: water retention (edema) on feet, legs or abdomen
Digestive organs: movement disorders of the gastrointestinal tract, bleeding, impaired absorption of nutrients (malabsorption)
Diagnosis of amyloidosis using a biopsy
A diagnosis in the early stages is rarely successful, since the symptoms of amyloidosis are not characteristic and rather point to other diseases. Comprehensive diagnostics are particularly important at an advanced stage. This is the only way to show the extent of the organ damage and the doctor can initiate appropriate therapy.
In addition to the medical history and physical examination, the doctor has various laboratory parameters determined, including blood count and liver values. Depending on the symptomatic organ, various imaging methods such as CT, MRI or ultrasound examination are available.
With the exception of cardiac amyloidosis, which is detected by means of skeletal scintigraphy, amyloidosis can only be diagnosed by tissue biopsy. For this purpose, the tissue is stained with Congo red – in polarized light the amyloid deposits show an apple-green color. A biopsy of the symptomatic organ is not absolutely necessary, rather fatty tissue, a biopsy of the bone marrow or the deep rectum can be performed.
If the screening biopsy is normal, however, a histological examination of the affected organ is usually carried out. In order to avoid misdiagnosis, the typing process then determines which type of amyloid is present.
Treat amyloidosis
In most cases, without treatment, amyloidosis progresses and the damage to the body increases continuously. The therapy of amyloidosis consists of the supportive treatment of the affected organ and a type-specific treatment. Supportive measures are intended to alleviate symptoms and improve quality of life:
Kidneys: In the case of edema, the intake of salt and fluids is reduced, and water tablets (diuretics) can also be used. The loss of protein is also kept in mind and compensated if necessary. In severe cases, a kidney transplant can be considered.
heart: If the heart muscle is damaged, less salt and fluids have to be taken in; diuretics are also indicated in this case. Other heart medications such as ACE inhibitors or beta blockers may not be used because they are poorly tolerated in cardiac amlyoidosis. In certain cases, a heart transplant combined with aggressive chemotherapy can be successful.
Stomach and intestines: The active ingredient loperamide can help against diarrhea, metoclopramide can be used in case of early satiety or early gastric emptying.
Nervous system: Pain in damaged peripheral nerves (neuropathy) can be relieved by the active ingredients gabapentin or pregabalin.
Special treatments are now available for most of the ten known forms of amyloidosis. In AL amyloidosis, conventional chemotherapy is usually used when the disease is first diagnosed, and high-dose chemotherapy and stem cell transplantation when the disease occurs again (relapse). Immune chemotherapy can also be considered: Antibodies are combined with mild to aggressive chemotherapy.
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