Kidney Amyloidosis

What is kidney amyloidosis?

Kidney amyloidosis is a condition in which abnormal proteins called amyloid build up inside the kidneys. Amyloid is made when certain proteins fold into the wrong shape, clump together, and form deposits that the body cannot easily clear. When these deposits settle in the kidneys, they damage the tiny filtering units (called glomeruli) that clean the blood. Over time, the kidneys may leak protein into the urine and gradually lose their ability to filter waste.

Amyloidosis is not a single disease. It is a group of related disorders, and the kidney is one of the organs most often affected. In some people the kidneys are the main organ involved; in others the heart, nerves, liver, or digestive tract are affected at the same time. Doctors usually describe the condition by the type of protein that forms the amyloid, because the type determines how it is treated.

The condition is rare. It is most often diagnosed in adults over the age of 50, and it is somewhat more common in men than in women, although anyone can develop it. Because early signs can be mild and easy to miss, kidney amyloidosis is frequently found when routine blood or urine tests show protein in the urine or reduced kidney function.

Kidney amyloidosis symptoms

Kidney amyloidosis symptoms depend on how much amyloid has built up, how quickly it accumulates, and whether other organs are involved. In the early stage many people have no symptoms at all. As protein loss through the urine increases and kidney function declines, symptoms often become more noticeable.

• Swelling (edema) in the legs, ankles, feet, or around the eyes, usually caused by low protein in the blood
• Foamy or frothy urine, a sign of large amounts of protein in the urine (proteinuria)
• Fatigue and weakness that does not improve with rest
• Loss of appetite and unintended weight loss
• Shortness of breath, especially when lying down or with mild activity
• Dizziness or lightheadedness when standing up
• Numbness, tingling, or pain in the hands and feet
• Easy bruising, including bruising around the eyes
• An enlarged tongue or changes in the voice, seen in some types

Swelling and foamy urine are the most typical kidney-related signs. When protein loss is heavy, doctors call the pattern nephrotic syndrome, which means a combination of high urine protein, low blood protein, swelling, and often high cholesterol. Symptoms such as shortness of breath, dizziness, or numbness may point to amyloid in the heart or nerves rather than in the kidneys alone.

In later stages, as the kidneys lose filtering capacity, people may notice nausea, itching, poor sleep, muscle cramps, and changes in how often they urinate. These are general symptoms of advanced chronic kidney disease and are not unique to amyloidosis.

Causes and risk factors

Kidney amyloidosis causes vary according to the type of protein involved. The most common types that affect the kidney are described below.

• AL (light chain) amyloidosis: This is the most frequent form affecting the kidney. It arises from a disorder of plasma cells, a type of white blood cell in the bone marrow. The abnormal plasma cells make excess pieces of antibody called light chains, which misfold and deposit as amyloid. AL amyloidosis is related to, but not the same as, multiple myeloma, a cancer of plasma cells.
• AA (secondary) amyloidosis: This form develops after years of chronic inflammation or infection. Conditions such as rheumatoid arthritis, inflammatory bowel disease, long-standing infections like tuberculosis, and inherited fever syndromes can trigger it. The kidney is the organ most often affected in AA amyloidosis.
• Hereditary (familial) amyloidosis: Inherited gene changes cause a normal protein to become unstable and form amyloid. Several different genes can be involved, and some forms mainly affect the kidneys while others mainly affect the nerves or heart.
• Dialysis-related amyloidosis: In people who have received long-term dialysis, a protein called beta-2 microglobulin can accumulate and form deposits, mostly in joints and bones rather than the kidney itself.
• Other rare forms: Several less common proteins can occasionally cause amyloid deposits in the kidney.

Risk factors depend on the type. Factors that may increase the chance of developing kidney amyloidosis include:

• Older age, particularly over 50 for AL amyloidosis
• Male sex, which carries a modestly higher risk
• A plasma cell disorder such as multiple myeloma or a related condition
• Long-term inflammatory diseases, especially when poorly controlled
• Chronic infections lasting many years
• A family history of amyloidosis or a known hereditary amyloid gene
• Many years of kidney dialysis

Kidney amyloidosis is not contagious, and it is not caused by diet or lifestyle in the way that some other kidney diseases can be. In many cases, particularly with AL amyloidosis, no specific trigger can be identified.

Diagnosis

Kidney amyloidosis diagnosis usually begins when a routine test shows protein in the urine or a rise in blood creatinine, a waste product that reflects kidney function. Because the symptoms overlap with many other kidney diseases, doctors rely on a step-by-step approach to confirm amyloid and identify its type.

• Urine tests: A urinalysis and a 24-hour urine collection, or a spot urine protein-to-creatinine ratio, measure how much protein the kidneys are leaking.
• Blood tests: These check kidney function (creatinine and estimated glomerular filtration rate), blood protein levels, cholesterol, and markers of inflammation.
• Protein studies: Serum and urine protein electrophoresis, immunofixation, and a serum free light chain assay look for abnormal antibody proteins that suggest AL amyloidosis.
• Kidney biopsy: This is the most definitive test. A small piece of kidney tissue is removed with a needle and examined under a microscope. A special stain called Congo red turns amyloid deposits a characteristic color, and they show an apple-green glow under polarized light.
• Amyloid typing: Once amyloid is found, laboratory techniques such as immunohistochemistry or mass spectrometry identify the exact protein. Typing is essential because treatment differs completely between AL, AA, and hereditary forms.
• Bone marrow biopsy: If AL amyloidosis is suspected, a sample of bone marrow is examined to look for abnormal plasma cells.
• Genetic testing: When a hereditary form is possible, a blood test can look for gene changes known to cause amyloidosis.
• Imaging and heart tests: Ultrasound of the kidneys, echocardiography (an ultrasound of the heart), an electrocardiogram, and sometimes cardiac MRI or specialized nuclear scans assess whether other organs are involved.

In some situations, doctors may sample a more accessible tissue, such as abdominal fat or the lining of the rectum, before deciding on a kidney biopsy. A positive result from these sites can confirm amyloid, though a kidney biopsy is often still needed to understand how the kidney has been affected. Diagnosis and treatment are usually shared between a nephrologist (kidney specialist) and a hematologist (blood specialist); at Acibadem, for example, these departments generally manage the condition together.

Treatment options

Kidney amyloidosis treatment options have two main goals: to stop or slow the production of the amyloid-forming protein, and to protect the kidneys and manage symptoms. There is currently no widely available treatment that reliably removes amyloid already deposited in the kidney, so early treatment to prevent further buildup is important. The right approach depends on the type of amyloid, the degree of kidney damage, and the person’s overall health.

• Treatment aimed at the underlying cause (AL type): Because AL amyloidosis comes from abnormal plasma cells, treatment uses medicines that target these cells. Chemotherapy-type drugs, steroids, proteasome inhibitors, and monoclonal antibodies that attack plasma cells are used, often in combination. These are the same kinds of medicines used for multiple myeloma, given in doses tailored to amyloidosis.
• High-dose chemotherapy with stem cell transplant: For selected people with AL amyloidosis who are fit enough, a high dose of chemotherapy followed by return of the person’s own stem cells (autologous stem cell transplant) may be offered. Eligibility depends on age, heart function, and kidney function, and not everyone is a suitable candidate.
• Treatment of the inflammatory disease (AA type): In AA amyloidosis, controlling the underlying inflammation or infection is the main treatment. This may involve anti-inflammatory medicines, biologic drugs that block inflammatory signals, or antibiotics for chronic infection. When inflammation is well controlled, further amyloid production often slows.
• Treatment for hereditary forms: Some hereditary types can be treated with medicines that stabilize the unstable protein or reduce its production. For certain forms, liver transplant has been used because the liver is where the abnormal protein is made.
• Kidney-protective and supportive care: Regardless of type, doctors usually recommend measures to protect kidney function. These may include blood pressure medicines that reduce protein leakage, water pills (diuretics) to control swelling, limiting salt intake, and careful monitoring of fluid balance. Doses of many medicines may need adjustment as kidney function changes.
• Dialysis: If the kidneys fail, dialysis can take over the job of filtering the blood. Both hemodialysis and peritoneal dialysis may be options, and the choice depends on the individual’s situation.
• Kidney transplant: A kidney transplant may be considered for some people whose amyloid production is well controlled and whose heart and other organs are healthy enough for surgery. Because amyloid can return in a new kidney if the underlying process is still active, transplant teams evaluate candidates carefully. More information on how transplant programs are organized is available through the Organ Transplantation unit.

Treatment is usually reviewed at regular intervals. Blood tests that measure the amyloid-forming protein show whether the underlying process is responding, while urine protein and creatinine levels show how the kidneys are doing. Your doctor may adjust or change treatments if the response is not adequate or if side effects are difficult to tolerate.

Living with kidney amyloidosis and outlook

The outlook for kidney amyloidosis varies widely and depends on several factors: the type of amyloid, how much kidney function has already been lost at diagnosis, whether the heart is involved, and how well the underlying process responds to treatment. Heart involvement is generally the strongest factor affecting survival in AL amyloidosis, while kidney-only disease tends to carry a better outlook. Treatments have improved considerably in recent years, and many people now live for years with the condition, though it usually remains a serious, long-term illness.

Day-to-day management often involves regular follow-up visits, routine blood and urine tests, and attention to diet. A dietitian may advise on reducing salt to help control swelling and blood pressure, and on adjusting protein or potassium intake depending on kidney function. Keeping a record of weight, swelling, and blood pressure at home can help the care team notice changes early.

Fatigue is common and may be related to the disease itself, to treatment, or to anemia (low red blood cell count). Gentle, regular physical activity within your limits is generally encouraged unless your doctor advises otherwise. Some people benefit from physical therapy or rehabilitation, particularly after intensive treatment or if nerve involvement affects balance and walking.

Living with a rare and complex illness can be emotionally demanding. Many people find it helpful to bring a family member to appointments, to write down questions in advance, and to ask for clear explanations of test results. Support groups for people with amyloidosis exist in many countries and can offer practical advice and a sense of connection.

Frequently asked questions

What is kidney amyloidosis in simple terms?

Kidney amyloidosis is a condition in which misfolded proteins called amyloid collect in the kidneys and damage their filtering system. Over time this causes protein to leak into the urine and kidney function to decline. It is rare, tends to affect adults over 50, and is classified by the type of protein involved, which guides treatment.

What are the first kidney amyloidosis symptoms people notice?

Early on, many people have no symptoms, and the condition is discovered through routine tests. When symptoms do appear, the most common early signs are swelling in the legs or around the eyes, foamy urine, and tiredness. Because these signs are also seen in many other conditions, they should be evaluated by a doctor rather than assumed to be amyloidosis.

What are the main kidney amyloidosis causes?

The most common cause is a plasma cell disorder that produces abnormal antibody fragments (AL amyloidosis). Long-standing inflammation or infection can cause AA amyloidosis, and inherited gene changes cause familial forms. In many cases, especially AL type, no specific trigger can be identified, and the condition is not caused by lifestyle choices.

How is kidney amyloidosis diagnosis confirmed?

Doctors usually start with urine and blood tests that show protein leakage and reduced kidney function. The diagnosis is confirmed by a biopsy, most often of the kidney, in which the tissue is stained with Congo red to reveal amyloid. Laboratory typing then identifies the exact protein, and further tests such as bone marrow examination, genetic testing, and heart imaging help determine the type and extent of involvement.

What kidney amyloidosis treatment options are available?

Treatment targets the source of the amyloid protein and protects the kidneys. For AL amyloidosis this means medicines directed at plasma cells and, for suitable candidates, stem cell transplant. For AA amyloidosis it means controlling inflammation. Supportive care includes blood pressure medicines, diuretics, and dietary changes. If the kidneys fail, dialysis and in selected cases kidney transplant may be considered.

Can kidney amyloidosis be cured?

Amyloidosis is generally considered a long-term condition rather than one that is fully cured. Treatment can often stop or greatly reduce the production of new amyloid, and in some people kidney function stabilizes or improves. However, existing deposits usually clear slowly, if at all, and ongoing monitoring is typically needed even when treatment has been successful.

Is kidney amyloidosis the same as multiple myeloma?

No, although they are related. Both involve abnormal plasma cells in the bone marrow. In multiple myeloma the cells multiply and cause bone damage, anemia, and other problems; in AL amyloidosis the main harm comes from the misfolded proteins the cells produce. Some people have both conditions at the same time, which is one reason a bone marrow test is part of the workup.

When to see a doctor

You should arrange to see a doctor if you notice persistent swelling in your legs or around your eyes, foamy urine, unexplained tiredness, or unintended weight loss, especially if you have a chronic inflammatory disease or a family history of amyloidosis. If you have already been diagnosed with kidney amyloidosis, keep to your scheduled follow-up visits and report any new or changing symptoms to your care team.

Seek urgent medical attention if you experience any of the following:

• Sudden or severe shortness of breath, or difficulty breathing when lying flat
• Chest pain, pressure, or a rapid or irregular heartbeat
• Fainting or repeated episodes of severe dizziness
• A marked drop in the amount of urine you produce, or no urine for many hours
• Rapid weight gain with worsening swelling over a few days
• Confusion, extreme drowsiness, or difficulty staying awake
• Fever, chills, or signs of infection while receiving chemotherapy or other treatments that lower the immune system
• Vomiting or diarrhea that prevents you from keeping fluids down
• Bleeding that does not stop, or blood in the urine or stool

These signs may indicate serious problems such as heart involvement, sudden worsening of kidney function, severe fluid overload, or infection, all of which need prompt evaluation.