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Amyloidosis

I
ntroduction of Amyloidosis
Amyloidosis is a rare disease that occurs when a substance called amyloid builds up in your organs. Amyloid is an abnormal protein that is usually produced in your bone marrow and can be deposited in any tissue or organ.

Amyloidosis can affect different organs in different people, and there are different types of amyloid. Amyloidosis frequently affects the heart, kidneys, liver, spleen, nervous system and digestive tract. Severe amyloidosis can lead to life-threatening organ failure.


S
ymptoms of Amyloidosis
Amyloidosis can affect any organ, and the symptoms depend on which organs are affected.
Most often amyloid is deposited in the kidneys and may cause kidney failure. Symptoms of kidney failure can include fluid retention (oedema), tiredness, weakness and loss of appetite.
Amyloid deposited in the heart can cause it to become enlarged and impair its ability to pump blood efficiently around the body. This may result in heart failure, which can cause symptoms such as shortness of breath and oedema.
Some of the other possible signs and symptoms of AL amyloidosis include:
Feeling lightheaded or fainting, particularly after standing or sitting up
Numbness or a tingling feeling in the hands and feet (peripheral neuropathy)
Frothy urine
An irregular heartbeat (arrhythmia)
Chest pain (angina)
In men, erectile dysfunction
Diarrhoea or constipation
Blood spots on the skin
Carpal tunnel syndrome – compression of the nerve in your wrist
An enlarged tongue

Al amyloidosis doesn’t usually cause any problems with memory loss, thinking speed, language, understanding, or judgement.


C
auses of AL amyloidosis
AL amyloidosis occurs when an abnormality in the plasma cells found in bone marrow (the spongy tissue at the centre of some bones) results in the excessive production of proteins called 'light chains'.
Normally, light chains form part of antibodies (proteins that help protect the body from illness and infection), but in cases of AL amyloidosis, large numbers of misfolded light chains are produced and these clump together into thread-like fibres that the body cannot clear away easily.
These fibres typically then gradually start to form deposits in the heart, kidneys, nerves, or liver.
The abnormal white blood cells in the bone marrow are usually benign (non-cancerous), but some cases of AL amyloidosis are linked to a type of bone marrow cancer called multiple myeloma.

Unlike some other types of amyloidosis, AL amyloidosis is not inherited, so a person with the condition cannot pass it on to their children.


D
iagnosis of AL amyloidosis
Diagnosis of AL amyloidosis can be challenging, since the symptoms are often very general.
The diagnosis can be confirmed by removing a biopsy (small tissue sample) from the affected part of the body, and examining this under a microscope in the laboratory, using special stains to check for amyloid proteins.
How the tissue sample is removed will depend on which parts of the body are affected. In some people with suspected anyloidosis, a biopsy of tummy fat (taken using a needle) or a biopsy from the gut (taken during an endoscopy) may give a positive result.
Other tests
Further diagnostic tests are also available which include a type of scan called SAP scintigraphy, which involves being injected with a mildly radioactive version of blood protein before being scanned with a gamma camera.
This protein coats any amyloid deposits in your body, which highlights most areas of the body affected by amyloid deposits.

You may also have further tests to assess how the amyloid deposits have affected your individual organs. For example, an echocardiogram (heart ultrasound scan) may be carried out to check the condition of your heart.


T
reatment of AL amyloidosis
There are currently no treatments available that can directly remove the amyloid deposits associated with AL amyloidosis. Treatment aims to prevent the further production of abnormal light chains while monitoring and treating any problems affecting your organs.
This can give your body enough time to gradually clear the deposits before they build up again and can help prevent organ damage.
In most cases, this will involve having chemotherapy to damage the abnormal bone marrow cells and inhibit production of the abnormal proteins.
You will also need treatment for organ failure – for example, you may need diuretic medication to treat heart failure and you may need dialysis if you have kidney failure.
Some people with kidney failure may be suitable to receive a kidney transplant, although the underlying bone marrow disorder will need to be suppressed by chemotherapy to prevent build-up of amyloid in the new kidney.

After chemotherapy, you will need regular check-ups every six to 12 months to look for signs of the condition returning (relapsing). If it does relapse at any stage, chemotherapy may need to be started again.

C
omplications of amyloidosis
The potential complications of amyloidosis depend on which organs the amyloid deposits affect. Amyloidosis can seriously damage your:
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.
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.
Nervous system. You may experience pain, numbness or tingling of the 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. Sometimes amyloidosis 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.

P
rognosis of AL amyloidosis
The outlook depends on the form of amyloidosis and its response to treatment. Systemic amyloidosis is slowly progressive and fatal if untreated. The average survival for AL amyloidosis is approximately one year while familial amyloidosis is up to 15 years. The outlook and life expectancy is adversely affected by vital organ involvement

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