Amyloidosis (am-uh-loi-DO-sis) is a rare disease that occurs when an abnormal protein, called amyloid, builds up in your organs and interferes with their normal function.
Amyloid isn’t normally found in the body, but it can be formed from several different types of protein. Organs that may be affected include the heart, kidneys, liver, spleen, nervous system and digestive tract.
Some varieties of amyloidosis occur in association with other diseases. These types may improve with treatment of the underlying disease. Some varieties of amyloidosis may lead to life-threatening organ failure.
Treatments may include chemotherapy similar to that used to combat cancer. Your doctor may suggest medications to reduce amyloid production and to control symptoms. Some people may benefit from organ or stem cell transplants.
There are many different types of amyloidosis. Some varieties are hereditary. Others are caused by outside factors, such as inflammatory diseases or long-term dialysis. Many types affect multiple organs, while others affect only one part of the body.
Subtypes of amyloidosis include:
- AL amyloidosis (immunoglobulin light chain amyloidosis). The most common type of amyloidosis in developed countries, AL amyloidosis is also called primary amyloidosis. It usually affects the heart, kidneys, liver and nerves.
- AA amyloidosis. Also known as secondary amyloidosis, this variety is usually triggered by an inflammatory disease, such as rheumatoid arthritis. Improved treatments for severe inflammatory conditions have resulted in a sharp decline in the number of cases of AA amyloidosis in developed countries. It most commonly affects the kidneys, liver and spleen.
- Hereditary amyloidosis (familial amyloidosis). This inherited disorder often affects the nerves, heart and kidneys. It most commonly happens when a protein made by your liver is abnormal. This protein is called transthyretin (TTR).
- Wild-type amyloidosis. This variety of amyloidosis occurs when the TTR protein made by the liver is normal but produces amyloid for unknown reasons. Formerly known as senile systemic amyloidosis, wild-type amyloidosis tends to affect men over age 70 and typically targets the heart. It can also cause carpal tunnel syndrome.
- Localized amyloidosis. This type of amyloidosis often has a better prognosis than the varieties that affect multiple organ systems. Typical sites for localized amyloidosis include the bladder, skin, throat or lungs. Correct diagnosis is important so that treatments that affect the entire body can be avoided.
Factors that increase your risk of amyloidosis include:
- Age. Most people diagnosed with amyloidosis are between ages 60 and 70, although earlier onset occurs.
- Sex. Amyloidosis occurs more commonly in men.
- Other diseases. Having a chronic infectious or inflammatory disease increases your risk of AA amyloidosis.
- Family history. Some types of amyloidosis are hereditary.
- Kidney dialysis. Dialysis can’t always remove large proteins from the blood. If you’re on dialysis, abnormal proteins can build up in your blood and eventually be deposited in tissue. This condition is less common with more modern dialysis techniques.
- Race. People of African descent appear to be at higher risk of carrying a genetic mutation associated with a type of amyloidosis that can harm the heart.
The potential complications of amyloidosis depend on which organs the amyloid deposits affect. Amyloidosis can seriously damage your:
- Heart. Amyloid reduces your heart’s ability to fill with blood between heartbeats. Less blood is pumped with each beat, and you may experience shortness of breath. If amyloidosis affects your heart’s electrical system, your heart rhythm may be disturbed. Amyloid-related heart problems can become life-threatening.
- Kidneys. Amyloid can harm the kidneys’ filtering system, causing protein to leak from your blood into your urine. The kidneys’ ability to remove waste products from your body is lowered, which may eventually lead to kidney failure and the need for dialysis.
- Nervous system. You may experience pain, numbness or tingling of your fingers or numbness, lack of feeling or a burning sensation in your toes or the soles of your feet. If amyloid affects the nerves that control your bowel function, you may experience periods of alternating constipation and diarrhea. If it affects the nerves that control blood pressure, you may feel faint after standing up too quickly.