Types of amyloidosis
AA amyloidosis
AA amyloidosis is a complication of long-standing inflammation. It is not inherited, and it is not a blood cancer: it develops when another illness keeps the body inflamed for years. Bringing that illness under control is what stops it — which makes AA the one form of amyloidosis that can genuinely be prevented.
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What is AA amyloidosis?
Key idea
AA amyloidosis is a rare complication of persistent inflammation, most often caused by a chronic inflammatory or infectious disease. Find the inflammation, treat it, and you stop the amyloid at its source.
A protein of inflammation
The amyloid in AA is made from serum amyloid A (SAA), a protein produced by the liver. It is normally present in the blood at low concentrations, and its production rises sharply whenever the body becomes inflamed.
That response is entirely normal — and harmless, so long as it is short-lived. The problem begins when inflammation lasts for years rather than weeks. SAA then circulates in excess, misfolds, and stacks into insoluble amyloid fibrils.
Which organs it reaches
The kidneys above all: they are affected in the great majority of patients, and it is usually a kidney problem that leads to the diagnosis.
The deposits also reach the digestive tract — stomach and intestines — as well as the liver and the salivary glands. Any illness capable of keeping the body inflamed over the long term can, in principle, lead to AA amyloidosis.
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How AA amyloidosis develops
Four steps that turn an ordinary immune response into a disease of the organs.
Step 01
Chronic inflammation
Another illness keeps the body inflamed: a long-running infection, an inflammatory arthritis, a bowel disease, an autoinflammatory syndrome.
Step 02
The liver makes SAA
In response, the liver raises its production of serum amyloid A. Blood levels stay high — not for days, but for years on end.
Step 03
Fibrils form
Circulating in excess, SAA misfolds and stacks into insoluble amyloid fibrils that the body cannot break down.
Step 04
Organ deposits
The fibrils settle in the tissues — first and foremost the kidneys — and progressively impair the way they work.
In AA amyloidosis, the inflammation has usually been present for several years before any amyloid begins to form.
03
What drives the inflammation
AA amyloidosis never arrives on its own. It follows another condition — and identifying which one is the first step of treatment.
Inflammatory arthritis
Joint diseases that keep the immune system active over decades are among the most frequent causes.
Autoinflammatory diseases
Genetic conditions that provoke recurrent bouts of inflammation, often from childhood. These are the patients for whom screening matters most.
Inflammatory bowel disease
Long-term inflammation of the digestive tract, when it is poorly controlled over many years.
Chronic infections
Infections that persist rather than resolve, particularly those of the lungs.
Blood disorders
Certain haematological diseases sustain an inflammatory state over the long term.
Solid tumours
A rarer cause, but a recognised one. Some tumours maintain chronic inflammation.
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Symptoms
The first signs are vague and easy to attribute to something else. By the time they become obvious, the kidneys are usually already involved.
Kidneys
The dominant feature
Swelling of the ankles, foamy urine, and a fatigue that rest does not lift. Blood tests show the kidneys are no longer filtering properly. Advanced kidney failure is the most serious complication of the disease, and can lead to dialysis.
Digestive tract
Stomach and intestines
Diarrhoea is the most common complaint. Blood may appear in the stool. Appetite fades, and weight is lost without any deliberate change in diet.
Liver
Often silent
The liver enlarges. Curiously, liver enzymes often remain normal, or barely raised — which is one reason the involvement can go unnoticed for a long time.
Thyroid and bladder
Some patients develop a goitre — an enlarged thyroid. When the bladder is involved, blood may appear in the urine.
Heart
Here AA differs sharply from AL. Deposits may be present in the heart, yet signs of heart failure are generally absent.
When to seek advice
If you live with a long-term inflammatory condition, these are the signs worth raising with the doctor who follows it.
- Swollen feet and ankles
- Foamy urine
- Fatigue that rest does not relieve
- Low blood pressure
- Nausea and vomiting
- Dry, itchy skin
- Muscle cramps
- Loss of appetite
- Diarrhoea, or blood in the stool
Caught early, kidney damage can be halted. That is the whole purpose of screening.
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How AA amyloidosis is diagnosed
The symptoms resemble those of far more common conditions of the kidneys, heart, lungs and liver. Many patients see several doctors before the diagnosis is finally made — which is why the sequence below matters.
01
Confirm with a biopsy
A biopsy is the only way to be certain. Kidney tissue is examined under the microscope to look for amyloid deposits.
02
Type the deposits
The deposits are then typed, to establish that the amyloid really is made of SAA protein and not of some other precursor.
03
Measure the inflammation
Circulating SAA and C-reactive protein (CRP) are measured. Past CRP results are reviewed too: they reveal how long the inflammation has been running.
04
Assess the organs
Blood and urine tests measure kidney function, and the heart is checked as well. Together they show how far the deposits have progressed.
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Treatment
Treatment aims to control the underlying inflammatory or infectious disease and reduce production of serum amyloid A (SAA), the precursor protein that forms AA amyloid deposits.
Treat the cause, not the deposits
The aim is to lower the excess of misfolded SAA by stopping the liver from overproducing it. There is only one way to do that: bring the underlying inflammatory disease under control.
It must be said plainly: no treatment currently removes amyloid fibrils once they have formed. What is already deposited stays. This is precisely why acting early — and screening those at risk — changes the course of the disease.
Familial Mediterranean fever
A daily anti-inflammatory, taken for life. It suppresses the recurrent inflammatory attacks and, with them, the rise in SAA.
Chronic infections
Antibiotics, to clear the infection that has been sustaining the inflammatory response.
Inflammatory disease
Corticosteroids or biological therapies, chosen according to the condition and how well it responds.
When the kidneys fail
In end-stage kidney failure, transplantation is possible for patients who are otherwise in good health. Dialysis may be needed in the meantime. Neither removes the amyloid — but both buy the time that controlling the inflammation requires.
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Prevention and follow-up
Screening
Prevention matters most for people who have lived with a genetic autoinflammatory disease since childhood. They need anti-inflammatory treatment for life, and a check once a year to catch amyloidosis before it has damaged anything.
Once a year
A urine test — to look for protein leaking from the kidneys
A blood test — to measure inflammation and kidney function
A shared follow-up
Once AA amyloidosis is confirmed, follow-up is close and involves several people at once: the doctor treating the underlying inflammatory disease, your GP, and a specialist in AA amyloidosis. Each sees a different part of the picture.
Some cases of AA amyloidosis may be prevented through early and sustained control of the underlying inflammatory or infectious disease. That is what makes the yearly check worth it.
FAQ
Common questions
Is AA amyloidosis inherited?
AA amyloidosis itself is not inherited — but some of the diseases that cause it are. Familial Mediterranean fever, CAPS, MKD and TRAPS are genetic autoinflammatory conditions, and they can run in families. If one of them has been diagnosed in your family, it is worth asking your doctor whether relatives should be assessed.
Can AA amyloidosis be prevented?
To a large extent, yes — and this sets AA apart from the other forms. Keeping the underlying inflammation under control keeps SAA levels down, and without an excess of SAA there is no raw material for amyloid. For people with a genetic autoinflammatory disease, lifelong treatment and an annual check are what prevention looks like in practice.
Does treatment remove the deposits?
No. No treatment currently available eliminates amyloid fibrils that have already formed. Treatment stops new ones from being made, which allows organs to stabilise and, in some cases, to recover part of their function. What has already been deposited remains.
Does AA amyloidosis affect the heart?
Deposits may be present in the heart, but unlike AL amyloidosis, signs of heart failure are generally absent. The kidneys, not the heart, drive the clinical picture in AA.
What is SAA?
Serum amyloid A is a protein made by the liver. It circulates in the blood at low levels, and its production increases as part of the body’s normal response to inflammation. In AA amyloidosis, inflammation that never switches off keeps SAA high for years, until some of it misfolds and forms deposits.
This page is intended as general information for patients, families and healthcare professionals. It does not replace medical advice. Always discuss your situation with your own specialist team.