Amyloidosis is a disease in which amyloid, an unusual protein that normally isn't present in the body, accumulates in various tissues.
Many forms of amyloidosis exist. In primary amyloidosis, the cause isn't known. However, the disease is associated with abnormalities of plasma cells, as is multiple myeloma, which may also be associated with amyloidosis. In secondary amyloidosis, the amyloidosis is secondary to another disease such as tuberculosis, infections of the bone, rheumatoid arthritis, familial Mediterranean fever, or granulomatous ileitis. A third form, hereditary amyloidosis, affects nerves and certain organs; it has been noted in people from Portugal, Sweden, Japan, and many other countries.
Another form of amyloidosis is associated with normal aging and particularly affects the heart. What causes amyloid to build up excessively usually isn't known. However, amyloidosis can be a response to various diseases that cause persistent infection or inflammation. Yet another form of amyloidosis is associated with Alzheimer's disease.Symptoms
The accumulation of large amounts of amyloid can disturb the normal functioning of many organs. The symptoms of amyloidosis depend on where the amyloid builds up. Many people have few symptoms, while others develop severe, life-threatening disease.
In primary amyloidosis, typical sites of amyloid buildup are the heart, lungs, skin, tongue, thyroid gland, intestines, liver, kidney, and blood vessels. This accumulation can lead to heart failure, an irregular heartbeat, difficulty in breathing, a thickened tongue, an underactive thyroid gland, poor absorption of food, liver failure, kidney failure, and easy bruising or other abnormal bleeding because of its effect on blood clotting. Nerves may malfunction, leading to weakness and abnormal sensations. Carpal tunnel syndrome may develop. When amyloid affects the heart, death may occur as a result of severe heart failure or an irregular heartbeat.
In secondary amyloidosis, amyloid tends to build up in the spleen, liver, kidneys, adrenal glands, and lymph nodes. The spleen and liver tend to enlarge and to feel firm and rubbery to the doctor who examines them. Other organs and the blood vessels may also be affected, although the heart is rarely involved.Diagnosis
Amyloidosis is sometimes difficult for doctors to recognize because it produces so many different problems. However, they may suspect amyloidosis when several organs fail or when a person bleeds easily for no apparent reason. The hereditary form is suspected when an inherited peripheral nerve disorder is discovered in a family.
The diagnosis is generally made by testing a small amount of abdominal fat obtained through a needle inserted near the navel. Alternatively, the doctor can take a sample of tissue for biopsy from the skin, rectum, gums, kidney, or liver. The amyloid shows up under the microscope with the use of special stains.Treatment
Amyloidosis doesn't always require treatment. When amyloidosis is caused by another disease, treating the other disease usually slows or reverses the amyloidosis. However, amyloidosis caused by multiple myeloma has a bleak prognosis; most people who have both diseases die within 1 to 2 years.
Treatment for amyloidosis hasn't been very successful. People may find relief by taking prednisone and melphalan, sometimes with colchicine. Colchicine alone may help relieve amyloidosis that's triggered by familial Mediterranean fever. Accumulations of amyloid (amyloid tumors) in a specific area of the body can sometimes be removed surgically.
A person whose kidneys have been destroyed by amyloidosis may receive a kidney transplant. Someone with heart problems may receive a heart transplant. However, the transplanted organs may later become affected by the buildup of amyloid. In the hereditary form, the amyloid-producing defect occurs in the liver; therefore, a few people have had successful liver transplants to stop the disease's progression.