Amyloidosis is a condition in which an abnormal protein called amyloid builds up in your tissues and organs. When it does, it affects their shape and how they work. Amyloidosis is a serious health problem that can lead to life-threatening organ failure.
Causes and Types of Amyloidosis
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 you have. Amyloid deposits may collect throughout your body or in just one area.
There are different types of amyloidosis, including:
Primary (systemic AL) amyloidosis. This occurs without a known cause, but it has been seen in people with a blood cancer called multiple myeloma. This is the most common type of amyloidosis. "Systemic" means it affects the entire body. The most commonly affected body parts are the kidney, heart, liver, intestines, and certain nerves. AL stands for "amyloid light chains," which is the type of protein responsible for this type of amyloidosis.
Secondary (systemic AA) amyloidosis. This is the result of another chronic inflammatory disease, such as lupus, rheumatoid arthritis, tuberculosis, inflammatory bowel disease (Crohn's disease and ulcerative colitis), and certain cancers. It most commonly affects the spleen, kidneys, liver, adrenal gland, and lymph nodes. AA means the amyloid type A protein causes this type of amyloidosis.
Dialysis-related amyloidosis (DRA). This is more common in older adults and people who have been on dialysis for more than 5 years. This form of amyloidosis is caused by deposits of beta-2 microglobulin that build up in the blood. Deposits can occur in many different tissues, but most commonly affects bones, joints, and tendons.
Familial, or hereditary, amyloidosis (AF). This is a rare form that is passed down through families. It is caused by an abnormal amyloid transthyretin (TTR) protein, which is made in the liver. This protein is responsible for the most common forms of hereditary amyloidosis.
Senile systemic amyloidosis (SSA). This is caused deposits of normal TTR in the heart and other tissues. It occurs most commonly in older men.
Organ-specific amyloidosis. This is cause deposits of amyloid protein in single organs, including the skin (cutaneous amyloidosis).
Risk Factors for Amyloidosis
Men get amyloidosis more often than women. Your risk for amyloidosis increases as you grow older. Amyloidosis affects 15% of patients with a form of cancer called multiple myeloma.
Amyloidosis may also occur in people with end-stage kidney disease who are on dialysis for a long time (see "Dialysis-related amyloidosis" above).
Symptoms of Amyloidosis
Symptoms of amyloidosis are often subtle. They can also vary greatly depending on where the amyloid protein is collecting in the body. It is important to note that the symptoms described below may be due to a variety of different health problems. Only your doctor can make a diagnosis of amyloidosis.
General symptoms of amyloidosis may include:
- Changes in skin color
- Clay-colored stools
- Feeling of fullness
- Joint pain
- Low red blood cell count (anemia)
- Shortness of breath
- Swelling of the tongue
- Tingling and numbness in legs and feet
- Weak hand grip
- Weight loss
Cardiac (Heart) Amyloidosis
Amyloid deposits in the heart can make the walls of the heart muscle stiff. They can also make the heart muscle weaker and affect the electrical rhythm of the heart. This condition can cause less blood to flow to your heart. Eventually, your heart will no longer be able to pump. If amyloidosis affects your heart, you may have:
- Shortness of breath with light activity
- An irregular heartbeat
- Signs of heart failure, including swelling of the feet and ankles, weakness, fatigue, and nausea, among others
Renal (Kidney) Amyloidosis
Your kidneys filter waste and toxins from your blood. Amyloid deposits in the kidneys make it hard for them to do this job. When your kidneys do not work properly, water and dangerous toxins build up in your body. If amyloidosis affects the kidneys, you may have:
- Signs of kidney failure, including swelling of the feet and ankles and puffiness around the eyes.
- High levels of protein in your urine.
Amyloid deposits along your gastrointestinal (GI) tract slow down the muscle contractions that help move food through your intestines. This interferes with digestion. If amyloidosis affects your GI tract, you may have:
Liver involvement can cause liver enlargement, fluid buildup in the body, and abnormal liver function tests.
Amyloid deposits can damage the nerves outside your brain and spinal cord called the peripheral nerves. The peripheral nerves carry information between your brain and spinal cord (central nervous system) and the rest of your body. For example, they make your brain perceive pain if you burn your hand or stub your toes. If amyloidosis affects your nerves, you may have:
- Balance problems
- Problems controlling your bladder and bowel
- Sweating problems
- Tingling and weakness
- Light-headedness when standing due to a problem with your body's ability to control blood pressure
A thorough physical exam and a detailed and accurate account of your medical history are crucial in helping your doctor diagnose amyloidosis.
There is no blood test to detect amyloidosis. Sophisticated laboratory techniques called electrophoresis or free light chain assays may reveal early evidence of some amyloid proteins.
A biopsy is needed to confirm a diagnosis of amyloidosis and determine the specific type of protein involved in the disease. The tissue sample for the biopsy may be taken from the abdominal fat pad, or sometimes the mouth, rectal, or other involved organs. It is not always necessary to biopsy the part of the body damaged by the amyloid deposits.
Genetic testing will be done if your health care provider suspects you have a type that is passed down through families. Treatment for hereditary amyloidosis is different than for other types of the disease.
Other blood, urine, and imaging tests will be done to check organ function.
There is no cure for amyloidosis. Your doctor will prescribe treatments to suppress the development of the amyloid-forming protein, and to manage your symptoms. If amyloidosis is related to another condition, then treatment will include targeting that underlying condition.
Specific treatment depends on what type of amyloidosis you have and how many organs are affected.
- High-dose chemotherapy with stem cell transplant can help remove the substance that leads to amyloid formation in those with primary AL amyloidosis who have no more than two major organs damaged. Chemotherapy medicines alone are used to treat other patients with primary AL amyloidosis.
- Secondary (AA) amyloidosis is treated by controlling the underlying disorder and with powerful anti-inflammatory medicines called steroids, which fight inflammation.
- Liver transplant may stop the disease in those with hereditary amyloidosis.
- A kidney or heart transplant may also be recommended.
Other treatments to help with symptoms may involve:
- Diuretic medicine to remove excess water from your body
- Thickeners to add to fluids to prevent choking in those who have swelling of the tongue
- Compression stockings to relieve swelling in the legs or feet
- Diet modifications, especially for those with gastrointestinal amyloidosis
What to Expect
Amyloidosis can be deadly, especially if it affects your heart or kidneys. Early diagnosis and treatment is important and can help improve survival. Without treatment, many patients die within two years of diagnosis.
Researchers continue to question why some types of amyloid make people sick and how the formation of amyloid can be stopped. Studies to investigate new treatments are ongoing. If you have amyloidosis, consider asking your doctor if there are any clinical trials you can participate in, or search for one by visiting www.clinicaltrials.gov and typing in the search term "amyloidosis."