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Amyloidosis

Amyloidosis is a group of diseases in which one or more organ systems in the body accumulate deposits of abnormal proteins. The name "amyloidosis" was first used more than 100 years ago but cases were described over 300 years ago. However, only within the past 20 years have physicians understood the specific make-up and structure of amyloid protein. Although amyloidosis is not cancer, it is very serious. It may be disabling or life threatening. However, growing awareness of the condition seems to be leading to substantial new research and treatment alternatives. Amyloidosis is a rare and potentially fatal disease that occurs when amyloid proteins build up in your body's organs. Amyloid is an abnormal protein produced by cells in your bone marrow that can deposit in any of your body's tissues or organs. Amyloidosis occurs when enough amyloid protein builds up in one or more organs to cause the organ or organs to malfunction. The disorder frequently affects the heart, kidneys, liver, spleen, nervous system and gastrointestinal tract.

Amyloidosis may be associated with certain forms of cancer (multiple myeloma, Hodgkin's disease) and the intestinal disorder, familial Mediterranean fever. In other cases, it may occur as a result of kidney disease in people who have undergone long-term dialysis therapy.

• fever
• Hodgkin's disease

There's no cure for Amyloidosis. However, medications and special diets can help you manage your symptoms and limit the production of amyloid protein.

Signs and symptoms

Signs and symptoms of amyloidosis depend on the organs affected. The wide range of signs and symptoms often makes amyloidosis difficult to diagnose. You may even have no symptoms. Signs and symptoms may include:

• Swelling of your ankles and legs

• Weakness

• Weight loss

• Shortness of breath

• Numbness or tingling in your hands or feet

• Diarrhea

• Severe fatigue

• An enlarged tongue (macroglossia)

• Skin changes

• An irregular heartbeat

• Difficulty swallowing

Causes

Doctors classify amyloidosis into three major forms:

• Primary amyloidosis. This type is the most common form of amyloidosis. It primarily affects your heart, lungs, skin, tongue, nerves and intestines. Primary amyloidosis isn't associated with other diseases.

• Secondary amyloidosis. This form occurs in association with chronic infectious or inflammatory diseases such as tuberculosis, rheumatoid arthritis or the bone infection, osteomyelitis. It primarily affects your kidneys, spleen, liver and intestines, though other organs may be involved. Treatment of the underlying disease may help stop this form of amyloidosis.

• Hereditary amyloidosis. As the name implies, this form of amyloidosis is inherited. This type often affects the nervous and digestive systems.

The cause of amyloidosis is unknown, but the disease begins in your bone marrow. In addition to producing red and white blood cells and platelets, your bone marrow makes antibodies — proteins that protect you against infection and disease. After antibodies serve their function, your body breaks them down and recycles them. Amyloidosis occurs when cells in the bone marrow produce antibodies that can't be broken down. These antibodies then build up in your bloodstream. Ultimately, they leave your bloodstream and can deposit in your tissues as amyloid, interfering with normal function.

• Rheumatoid arthritis

• Tuberculosis

Risk factors

Anyone can develop amyloidosis, but the majority of people who get amyloidosis are older than 50. Although amyloid is an abnormal protein, the amount of protein you eat plays no role in the development of the disease. Also, there's no recognized link between amyloidosis and stress or occupation.

You may be at increased risk if you have a chronic infectious or inflammatory disease, a family history of the disease, or multiple myeloma — a form of bone marrow cancer. Ten percent to 15 percent of people who have multiple myeloma develop amyloidosis.

In addition, if you have kidney disease requiring kidney dialysis — particularly for longer than five years — you may be at increased risk. This is because dialysis can't remove large proteins from the blood, so abnormal proteins may build up and deposit in surrounding tissues.

When to seek medical advice

If you persistently experience any of the signs or symptoms listed earlier, they may indicate amyloidosis or other serious diseases. See your doctor to determine the underlying cause.

Screening and diagnosis

In order to rule out other conditions, your doctor may conduct a physical exam and a variety of tests, including blood and urine tests.

Though blood or urine tests may detect an abnormal protein — which could indicate amyloidosis — the only definitive test for amyloidosis is a tissue biopsy. In this biopsy, the doctor uses a needle to remove a small sample of tissue. If your doctor suspects that you have systemic amyloidosis — meaning it affects several parts of your body rather than just one organ — the biopsy may be taken from your abdominal fat, bone marrow or rectum. The sample is then examined under a microscope in a laboratory to check for signs of amyloid. These biopsies are relatively minor procedures conducted in an outpatient setting with a numbing medication (local anesthetic).

Occasionally, tissue samples may be taken from your liver, nerves, heart or kidney to help diagnose the specific organ affected by amyloidosis. These procedures may require hospitalization.

Complications

The severity of amyloidosis depends on which organs the amyloid deposits affect. Potentially life-threatening situations include kidney failure and congestive heart failure:

• Kidney damage. When amyloidosis affects your kidneys, their filtering system is damaged, causing protein to leak from your blood into your urine. When large amounts of protein leave the bloodstream and appear in the urine, the loss of protein from your blood causes fluid to leak out of the blood vessels. This can cause your feet, ankles and calves to swell (edema). Ultimately, damage to the kidneys' filtering system inhibits your kidneys' ability to remove waste products from your body, which may cause kidney failure.

• Heart damage. When amyloidosis affects your heart, the most common symptom is shortness of breath, even with the slightest exertion. You may find it difficult to climb a flight of stairs or walk long distances without stopping to rest. When amyloid protein builds up in your heart, it reduces your heart's ability to fill with blood in between heartbeats. This means less blood is pumped with each beat. Your heart will have difficulty keeping up with your body's demand for blood during exertion. And when amyloidosis affects the electrical system of your heart, this may disturb your heart's rhythm.

Another potential complication of amyloidosis is disruption of your nervous system function. In about 40 percent of people with amyloidosis, this may include carpal tunnel syndrome — characterized by pain, numbness or tingling of the fingers. Disruption of another area of your nervous system might cause numbness or a lack of feeling in your toes or soles of your feet, or a burning sensation in these areas due to nerve irritation. Over time, this kind of disruption can cause weakness of your legs.

• Carpal tunnel syndrome

• Diarrhea

• Heart failure

• Kidney failure

If amyloid deposits affect the nerves that control your bowel function, you may experience periods of alternating constipation and diarrhea. Sometimes the condition affects nerves that control blood pressure, and you may experience dizziness or near fainting when standing too quickly as a result of a drop in your blood pressure.

• constipation

• Heart failure

Other complications may include bowel obstruction and enlargement of the liver.

Treatment

Though there's no cure for amyloidosis, treatment may help manage symptoms and limit further production of amyloid protein. Managing amyloidosis is primarily done with medications and diet. Well-balanced nutrition is important to provide your body with an adequate energy supply.

Because amyloidosis can cause a number of complications, you may also need treatment for those specific conditions — such as a special diet — based on your symptoms and affected organs. For example, if amyloidosis affects your heart or kidneys, you may be asked to follow a low-salt diet to limit fluid retention. Or your doctor may prescribe diuretics and other medications. In some cases, your doctor might prescribe medication for pain control.

If you have secondary amyloidosis, the primary goal of therapy is to treat the underlying condition — for example, taking an anti-inflammatory medication for rheumatoid arthritis.

• chemotherapy

• Rheumatoid arthritis

Researchers are studying other therapies to determine their place in the treatment of amyloidosis. Ask your doctor whether these treatments are appropriate for you. Some of these include:

• Peripheral stem cell transplantation. Peripheral stem cell transplantation involves using high-dose chemotherapy and transfusion of previously collected immature blood cells (stem cells) to replace diseased or damaged marrow. These cells may be your own (autologous transplant) or from a donor (allogeneic transplant).

• Liver transplantation. Studies indicate that in people with hereditary amyloidosis, liver transplantation may be an effective treatment because the protein that causes this form of amyloidosis is made in the liver.

• Other therapies. Therapies include melphalan (Alkeran), an agent also used to treat certain types of cancer, and prednisone, a corticosteroid used for its anti-inflammatory effects. Several medications — such as thalidomide, a drug now used to treat multiple myeloma — are being tested for their ability to inhibit the disease. Your doctor may be aware of clinical trials available to you.

Self-care

If you feel short of breath, take a rest. Although you'll need to avoid strenuous activities, you may be able to continue normal daily activities, like going to work. Talk to your doctor about what's an appropriate level of activity for you.