A group of disorders in which abnormal proteins accumulate in internal organs
The various rare conditions known as amyloidosis develop when deposits of abnormal proteins, called amyloid, collect in organs and interfere with their function. There are various forms of amyloidosis, each of which is caused by a different type of amyloid. The condition mainly affects elderly people and is more common in men than in women.
Amyloidosis may be due to an abnormal gene or have no apparent cause; in these cases it is called primary amyloidosis. More commonly, it occurs as a complication of another disorder and is therefore called secondary amyloidosis. Disorders associated with the condition include inflammatory disorders such as rheumatoid arthritis, long-term infections, and the bone marrow cancer multiple myeloma.
Often, there are no symptoms in the early stages of amyloidosis. Over months or years, various symptoms develop, depending on which organs and tissues are affected. Diseased organs such as the kidneys, heart, liver, and nerves often become enlarged and cannot function properly. Resulting complications may include chronic kidney failure, chronic heart failure, chronic liver failure, or nerve damage (see Peripheral neuropathies). If amyloid deposits build up in the brain, Alzheimer’s disease may develop as a result.
Amyloidosis is diagnosed by examining a tissue sample from an affected organ under a microscope to detect deposits of protein. In cases of secondary amyloidosis, treating the underlying disorder may halt or even reverse the condition. However, amyloidosis that is associated with multiple myeloma tends to progress rapidly, and the outlook is poor. For primary amyloidosis, immunosuppressant drugs or drugs that are more commonly used in the treatment of cancer (see Anticancer drugs) may be prescribed. If amyloidosis has already caused the failure of an organ, a transplant may be a treatment option, but the replacement organ could also be affected if the disease is not controlled.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.