Amyloidosis is a rare condition that develops when a protein called amyloid builds up in the organs. Amyloid is an abnormal protein typically produced in the bone marrow and can be unloaded in any tissue or organ.
The disease may affect different organs in different people with different types of amyloid build up. Frequently affected organs include the heart, kidneys, liver, nervous system, spleen and digestive tract. Severe amyloidosis can be life threatening and result in organ failure.
There is no cure for amyloidosis; however, there are treatments to manage the symptoms and regulate the production of amyloid protein.
Signs and symptoms of amyloidosis may not be evident until the disease is advanced. The symptoms vary relative to which organ is affected.
Symptoms of amyloidosis can include:
- Severe fatigue and weakness
- Shortness of breath
- Swelling of the ankles and legs
- Numbness, tingling or pain in the hands or feet, especially pain in the wrists (carpal tunnel syndrome)
- Diarrhea (may occur with blood) or constipation
- Significant weight loss
- Difficulty swallowing
- Enlarged tongue
- Skin changes (thickening or easy bruising) and purplish patches around the eyes
- Irregular heartbeat
Amyloidosis is caused by the build up of the abnormal protein amyloid. Produced in the bone marrow the amyloid proteins can be deposited in any organ in the body. However, the exact cause of the condition can be determined on the type of amyloidosis:
- Immunoglobulin light chain (AL) amyloidosis: Previously known as primary amyloidosis, this is the most common type of amyloidosis and it can affect the heart, kidneys, liver, skin and nerves. The cause of this type of amyloidosis is abnormal antibodies produced by the bone marrow and deposited in tissue as amyloid.
- AA amyloidosis: AA amyloidosis occurs along with chronic infectious or inflammatory diseases such as rheumatoid arthritis or inflammatory bowel disease and it mostly affects the kidneys. It can sometimes affect the liver, heart or digestive tract as well. AA amyloidosis was formerly known as secondary amyloidosis.
- Hereditary (familial) amyloidosis: An inherited disorder that usually affects the liver, heart, nerves and kidneys. The main cause is a buildup of a specific amyloid called transthyretin amyloid that may affect the nervous system or the heart. This disorder is considered to be a serious cause of heart failure in African-American men.
- Dialysis-related amyloidosis: This type of amyloidosis usually affects people on long-term dialysis. It occurs when proteins in the blood are deposited in joints and tendons causing pain, stiffness and fluid in the joints along with carpal tunnel syndrome.
Risk factors for amyloidosis include:
- Age: The most common type of amyloidosis, AL amyloidosis, occurs in people aged 50 or older.
- Gender: Around 70% of people diagnosed with AL amyloidosis are men.
- Other conditions: A chronic infectious or inflammatory disease increases the risk of AA amyloidosis.
- Family history: Family history is a significant factor in hereditary amyloidosis.
- Dialysis: Long-term dialysis can cause abnormal proteins to build up in the blood and be deposited in tissue thus increasing the risk of dialysis-related amyloidosis.
The complications associated with amyloidosis mainly vary according to which organs are affected.
- Kidneys: The kidneys’ filtering system may be damaged from the amyloid that can cause protein to leak from the blood to the urine. The impaired ability of the kidneys to remove waste products may lead to kidney failure.
- Heart: Amyloid buildup decreases the heart’s ability to fill with blood between heartbeats. Shortness of breath may be a sign that less blood is pumped with each heartbeat. The heart rhythm may also be disturbed if the amyloidosis affects the electrical system of the heart.
- Nervous system: Symptoms such as pain, numbness, tingling or burning sensations in the fingers and toes can occur as a result of the nervous system being affected. Amyloid can also affect the nerves that control the bowel function causing episodes of constipation and diarrhea. Moreover, amyloidosis can affect the nerves that control the blood pressure causing the blood pressure to drop.