Amyloid is material that can be seen under the microscope and consists of small collections of protein strands. Amyloid itself is not harmful, but sometimes it is laid down within body tissues where it can interfere with normal function.
When doctors look at a kidney biopsy (a small piece of kidney removed with a needle) under the microscope, amyloid can be seen in blood vessels and in the filtering elements of the kidney. Damage to the filtering elements is the most important problem, and can cause either protein loss with fluid retention, or in some cases it can cause kidney failure.
Protein loss with fluid retention.
The obvious sign of this is ankle swelling. In some severe cases the swelling may affect the legs up to the thighs, with fluid around the hands and face. Fluid can collect internally, causing abdominal swelling or breathlessness.
This is normally detected by blood tests which measure chemicals the kidney should be eliminating from the body. Other symptoms of kidney failure can include itching or tiredness and sickness. Fortunately many amyloid patients do not develop kidney failure.
This varies from case to case, so that no two people with amyloid have exactly the same problems. Amyloid can affect many parts of the body, and here is a list of some of the problems. There may be none of these problems, and it is very unlikely that all of them could develop.
Amyloid can affect small blood vessels inside the skin. This makes the blood vessels fragile, and bruising may occur very easily, particularly on the forearms or around the eyes.
It is quite common for parts of the bowel to be affected by amyloid. This can cause a tendency to diarrhoea or constipation, or in some cases difficulty swallowing or sickness.
Bones and Joints
Amyloid can cause swelling around joints, although this is not usually a major problem. There can be compression of one of the nerves to the hand around the wrist, and if there is numbness or tingling in the thumb or palm of the hand you should tell your doctor, as this can usually be dealt with by simple surgery.
Occasionally amyloid can upset nerves as they run down the body to the feet. This can cause pains or numbness in the feet.
Heart and LiverThese organs can have amyloid deposited inside them. It is normal for doctors to measure liver function by blood tests and perform an electrocardiograph (heart tracing).
Several types of protein can cause amyloid. By far the commonest are fragments of antibodies. This occurs if the bone marrow overproduces a single antibody molecule by mistake. This overproduction by the bone marrow is very common as we get older, and fortunately only causes amyloid in a very few cases.
If amyloid is caused by antibodies, doctors will discuss the case with blood specialists, who may perform a bone marrow test. In most cases amyloid is caused by a benign growth of the bone marrow, but sometimes there is a more serious condition called myeloma.
Rarely, amyloid is caused by chronic severe inflammation in the body, such as some types of arthritis. Very rarely, amyloid runs in families, but the amyloid protein is not an antibody in these cases.
Amyloid is not usually curable, but doctors are able to offer symptom control. There are several types of treatment.
Fluid retention.This requires control of the amount of fluid that is drunk, and usually tablets (diuretics or water tablets) to make the kidneys produce more urine. The amount of salt added to food or used in cooking must be reduced. Occasionally, if there is severe fluid retention, it may be necessary to be admitted to hospital for a few days and use protein drips to help remove fluid.
There may be a low level of protein in the body. Therefore, if the diet does not contain adequate protein, the body may become weak. Dieticians can give you specialist dietary advice about eating well to keep strength up.
Amyloid can cause blood clots in the body, and in some cases doctors will advise anticoagulation of the blood with warfarin tablets.
Chemotherapy for the Bone Marrow.
In some cases where antibody production is causing amyloid, doctors will try to suppress the bone marrow with drugs, normally courses of tablets. The risks and possible benefits of such treatment will be discussed with each individual case.
This varies from case to case, depending on how amyloid has affected the body. Some amyloid patients lead essentially normal lives, others have to accept some limitations due to weakness or breathlessness. Everyone should be as active as possible, and aim to lead as normal a life as possible.
Adapted from a leaflet written by Rob Higgins, Renal Consultant, Walsgrave Hospital, Coventry, 1998
The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.