Amyloidosis is a condition in which one or more organ systems in the body accumulate deposits of abnormal proteins known as amyloid. The buildup may happen in a single organ or throughout the body. Amyloid deposits can affect any organ or tissue. Amyloidosis is rare, and the exact cause is unknown.
Risk factors include age, gender, other diseases and family history. The risk of amyloidosis increases as a person gets older. Amyloidosis is more common in men than women.
Amyloidosis is also sometimes associated with the presence of another disease. For example, 12% – 15% multiple myeloma patients also develop amyloidosis. Hereditary amyloidosis can run in families, possibly due to a genetic mutation that is passed down from generation to generation.
Amyloidosis can also occur in people with end-stage kidney disease who are on dialysis for a long time. This is called dialysis-related amyloidosis. It is caused by deposits of beta-2 microglobulin that build up in the blood. It is more common in older adults and people who have been on dialysis for more than five years.
Many different proteins can lead to the formation of amyloid deposits, but only a few have been linked to significant health problems. The type of protein and where it collects determines the type of amyloidosis. Amyloid deposits may collect throughout the body or in just one area.
There are several types of amyloidosis:
Primary (systemic AL) amyloidosis
This is the most common type of amyloidosis in the United States. AL stands for “amyloid light chains,” which is the type of protein responsible for this type of amyloidosis. AL amyloidosis is sometimes associated with multiple myeloma. AL amyloidosis is systemic, affecting, the entire body. The most commonly affected body parts include the kidney, heart, liver, intestines, and certain nerves.
In AA amyloidosis, the amyloid protein that accumulates in the tissues is known as the A protein. AA amyloidosis is associated with aging and such chronic diseases as diabetes, tuberculosis, rheumatoid arthritis, or inflammatory bowel disease. he spleen, liver, kidneys, adrenal glands, and lymph nodes may be involved.
Hereditary amyloidosis is rare and can be passed down through families. ATTR stands for the amyloid transthyretin (TTR) protein. This protein is responsible for the most common forms of hereditary amyloidosis. It can cause peripheral sensory and motor neuropathy problems (issues relating to the central nervous system), carpal tunnel syndrome, and eye abnormalities.
Symptoms of amyloidosis can be subtle and vary greatly depending upon where the amyloid deposits are in the body. General symptoms of amyloidosis may include:
A biopsy is the only way to make a definitive diagnosis of amyloidosis. Imaging tests may be used to find out whether organs, such as the heart or kidneys, are involved.
In addition to a physical examination, the following tests may be used to diagnose amyloidosis:
Heart evaluation (ECG and Echo)
Bone marrow biopsy and aspiration
Treatment options and recommendations depend on several factors, including the type of amyloidosis, the type of underlying disease, if there is one, and possible side effects.
Therapies include some chemotherapy drugs such as chlorambucil (Leukeran), melphalan (Alkeran), and cyclophosphamide (Cytoxan, Neosar), and dexamethasone, a corticosteroid used for its anti-inflammatory effects. These drugs interrupt the growth of the abnormal cells that produce amyloid protein.
Newer chemotherapy regimens used for the treatment of multiple myeloma are being evaluated for amyloidosis.. These include bortezomib (Velcade), thalidomide (Thalomid) and a thalidomide derivative called lenalidomide (Revlimid). These drugs may be used alone or in combination with dexamethasone.
Peripheral blood stem cell transplantation involves using high-dose chemotherapy and transfusion of previously collected stem cells to replace diseased marrow.
Immunotherapy is designed to enhance the body’s natural defenses. It uses materials made either by the body or in a laboratory to strengthen, target, or restore immune system function. Alpha interferon is a form of biologic therapy given as injections under the skin. This is sometimes used to help relieve symptoms caused by amyloidosis.
Surgery used to treat amyloidosis may include organ transplantation. Liver transplantation has been effective in certain types of hereditary amyloidosis.
Dietary therapy may be used to decrease amyloid protein production or to decrease the burden on affected organs.