Amyloidosis is a group of diseases in which abnormal proteins, called amyloid proteins, accumulate in organs or organ systems such as the heart, kidneys, nervous system or gastrointestinal tract. There are different types of amyloidosis, dependent on the type of protein being deposited in tissues.
The most common form of amyloidosis in the United States is called primary amyloid. In primary amyloid, the protein being deposited is a part of the antibody protein called the light chain.
Primary amyloid is now a treatable disease. The mainstays of therapy are the same agents used to treat a related bone marrow cancer, called multiple myeloma. Treatment options include chemotherapy, corticosteroid medicines, biologic agents, and in some instances, autologous stem cell transplantation. The goal of therapy is to halt the buildup of amyloid protein in organs and to prolong life.
Fortunately, amyloidosis is rare, affecting about eight out of every 1 million people annually. The majority of those affected are more than 40 years of age and 60 percent are male, although the condition can affect anyone. The cause is unknown.
There are three main types of amyloidosis:
Symptoms of amyloidosis depend on the organs it affects. The wide range of symptoms often makes amyloidosis difficult to diagnose. Some people may not experience any symptoms and others may have many symptoms. Frequently described symptoms include:
A complete medical history and physical examination is essential for diagnosing amyloidosis. Blood, urine and bone marrow tests also must be performed. Blood or urine tests can detect the amyloid proteins, but only bone marrow tests or other small samples of tissue — called biopsies — can positively establish the diagnosis of amyloidosis.
A small tissue sample, or biopsy, will often be taken from the abdominal fat, rectum, and/or bone marrow to confirm the diagnosis of amyloidosis. These biopsies are relatively minor procedures done in an outpatient clinic with a local anesthetic (numbing medication). Occasionally, samples need to be taken from damaged organs such as the liver, intestines, heart or kidney. The type of biopsy procedure required will vary from patient to patient.
Treatment of amyloidosis is given to improve symptoms and extend life. Treatment can limit further production of amyloid proteins and, in some instances, promote the breakdown of amyloid proteins in affected organs. The type of treatment required varies depending on the type of amyloidosis and the patient's symptoms.
With secondary amyloid, the main goal of therapy is to treat the underlying condition — for example, taking an anti-inflammatory medication for rheumatoid arthritis or antibiotics for an infection.
In hereditary amyloid, liver transplantation has been the most effective therapy. The new liver does not produce the abnormal amyloid proteins and consequently the disease improves. Investigational drugs are also being evaluated to try and prevent this type of amyloid protein from depositing in organs.
Reviewed by health care specialists at UCSF Medical Center.