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
