Amyloidosis

Amyloidosis is a group of disorders characterized by the accumulation of an insoluble protein called amyloid fibrils in various body organs, interfering with their normal function. The organs involved are the heart, liver, spleen, kidneys, nervous system, and digestive tract. Due to the involvement of various organs, the symptoms are often vague and take some time before the diagnosis is made. Some key features may be the presence of proteins in the urine, non-specific organ enlargement, and nervous system (peripheral nerves) disorders. There are many types of amyloidosis caused by genetic and environmental factors. Biopsy of the tissue involved can lead to a precise diagnosis. It is treated by removing the underlying cause and using certain medications for specific types directed at decreasing the production of amyloid fibrils. 

Amyloidosis is classified according to the kind of protein they make and the underlying cause. Some affect multiple organs, while only one organ can also be involved. The most common types are:

AL amyloidosis: This is the most common type where the ‘L’ stands for light chains. It is also known as primary amyloidosis and affects the heart, liver, kidneys, and nerves. It is mainly associated with a blood cancer called multiple myeloma.

AA amyloidosis: This type is triggered by inflammatory disorders like rheumatoid arthritis and Crohn's disease. Treating the underlying disorder can also bring down protein levels. The organs most commonly involved are the kidneys, liver, and spleen. It is also called secondary amyloidosis.

Hereditary amyloidosis: It is an inherited disorder also known as familial amyloidosis. It often involves the nerves, heart, and kidneys. In this type, the liver makes an abnormal protein called transthyretin (TTR).

Wild-type amyloidosis: In this type, the liver makes a normal TTR protein but still accumulates amyloid fibrils for unknown reasons. It affects people over age 70 and is called senile systemic amyloidosis. It mainly affects the heart and may also lead to carpal tunnel syndrome.

Localized amyloidosis. This type does not affect the whole body. Instead, it targets specific organs such as the bladder, throat, skin, or lungs. It has a better outcome if the diagnosis is made correctly. 

The following factors may increase your chances of amyloidosis;

·         Age. The most common age group affected is between ages 60 and 70, with some exceptions.

·         Sex. It affects men more commonly.

·         Inflammatory disorders: The presence of other chronic inflammatory diseases increases the risk.

·         Family history: Some types are transferred from parents to children.

·         Kidney dialysis. Dialysis can result in the accumulation of some proteins that cannot be removed by the procedure.

·         Race: Some races are prone to get the hereditary type, such as the African race.  

Amyloidosis is found worldwide. AL amyloidosis affects around 3–13 per million people annually, and AA amyloidosis occurs in about 2 per million people per annum. The common age group affected by these two types is 55 to 60.

Initially, you may have vague symptoms. Symptoms specific to the organs involved will appear late in the disease. Some of the general symptoms are;

·         Severe weakness

·         Unexplained weight loss

·         Low levels of red blood cells

·         Difficulty breathing

·         Tongue swelling

·         Skin color changes

·         Purple patches around the eyes

·         Joint pain

·         Heart disease symptoms: Shortness of breath, especially upon activity and lying down, irregular heartbeat, swelling of the feet and ankles.

·         Kidney disease symptoms: feet and ankles welling and swelling around eyes, increased protein levels in urine

·         Gut disease symptoms: Nausea, diarrhea, abdominal pain, decreased appetite, liver enlargement

·         Symptoms of nerve disease: Tingling sensations on the body, balance control problems, inability to control bladder and bowel. 

Symptoms of amyloidosis can be vague, but a precise diagnosis must be made to treat it efficiently. You should consult your healthcare provider upon doubt of having the disorder. Your physician will elicit a detailed history and perform a physical examination. For confirmation of diagnosis, you may need to undergo the following investigations;

Check for proteins: Abnormal proteins can be identified in the blood and urine samples submitted in the laboratory. Some other tests can be ordered to check for thyroid and liver disease.

Biopsy: Biopsy of the tissue sample affected is the key to making the diagnosis. A small tissue is taken out from your body and examined in the laboratory to identify the correct type and treat it specifically.

Imaging tests: Imaging tests can also help identify the damage done to the organs—for example, echocardiograms, CT scans, MRI scans, etc.

Genetic testing: These tests diagnose the hereditary type of amyloidosis based upon the history of a family member affected. 

Several disorders can look like amyloidosis;

·         Restrictive cardiac disease

·         Alcoholic liver disease

·         Alzheimer's Disease.

·         Anorexia Nervosa.

·         Bulimia Nervosa.

·         Chronic Obstructive Pulmonary Disease.

·         Cirrhosis.

·         Colorectal Cancer

Different types are treated differently. Amyloidosis caused by other disorders demands the treatment of the underlying cause. Treatment is directed towards managing the symptoms and decreasing the production of the protein fibrils.

Chemotherapy: Some medicines used to treat cancer are also used in amyloidosis to decrease the production of the amyloid fibrils. For example, melphalan and cyclophosphamide-bortezomib-dexamethasone are used to treat the AL type.

Targeted medicines: Some medicines work on the cells and interrupt the production of amyloid via various mechanisms. For example, patisiran, inotersen, tafamidis and diflunisal.

Supported therapies: For controlling the heart symptoms, you may be prescribed blood thinners, diuretics, etc. For kidney disease, you may be advised to undergo dialysis to substitute for the deranged function of the kidneys.

Stem cell transplant: In this procedure, your stem cells are collected from your blood and saved for the later infusion back into your body after chemotherapy.

Organ transplant: Depending on the organ involved, an organ transplant can be offered—for example, the heart, liver, kidneys, etc.  

The outcome of the disorders depends on the type of the disease and the organs involved. For the AL type, survival is 6 months if left untreated. For the AA type, the outcome depends on the organ involved, treatment given, and the resulting improvement in the protein levels. For transthyretin type, the survival is better and unrelated to age or gender. 

Some of the lifestyle changes can help you cope with the disorder;

• Avoid drinking alcohol to prevent further damage to the liver
• Consume a healthy diet rich in vitamins A, E, K, vitamin D and calcium, minerals, omega 3 fatty acids, antioxidants,
• Employ regular exercises to improve inactivity and combat fatigu
• Salt and water intake can be adjusted in cases of heart and kidney disease
• Genetic testing can be offered to other family members for early diagnosis and treatment for a better outcome of the hereditary type.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 11, 2023. 

References

https://www.nhs.uk/conditions/amyloidosis/#:~:text=Amyloidosis%20is%20the%20name%20for,and%20tissues%20to%20work%20properly.

https://ashpublications.org/blood/article/136/23/2620/474251/Management-of-AL-amyloidosis-in-2020