About 4,000 people in the United States are diagnosed each year with amyloid light-chain (AL) amyloidosis, the most common type of amyloidosis. However, amyloidosis, in general, is underdiagnosed. Many people do not hear about amyloidosis until they or someone they love receives the diagnosis. This rare condition is usually diagnosed through blood tests.

Several blood tests may be used to diagnose amyloidosis and to check the overall health of people living with the condition. .

What Is Amyloidosis?

Amyloidosis occurs when abnormal proteins called amyloid build up in the blood. Amyloid isn’t normally made by the body — rather, it can show up as the result of a genetic abnormality or other health conditions. Over time, this type of protein can build up in the tissues of various organs, impairing their functions. A buildup of amyloid can affect the liver, spleen, nervous system, and gastrointestinal tract, though the most commonly affected organs are the kidneys and the heart.

There are several types of amyloid that cause different types of amyloidosis, including:

• AL amyloidosis
• AA amyloidosis — Also called secondary amyloidosis; develops when the liver makes abnormal serum amyloid A protein
• Hereditary ATTR amyloidosis — Caused by a mutation in a gene that makes the transthyretin (TTR) protein
• Wild-Type ATTR amyloidosis — Develops from the TTR protein, but does not involve mutations in the TTR gene

Once your health care team has diagnosed the type of amyloidosis you have, they will be better able to determine the right treatment options to target the specific amyloid proteins.

Blood Tests for Diagnosing Amyloidosis

Doctors use various blood tests as diagnostic tools to determine whether or not a person has amyloidosis. No individual blood test can definitively diagnose amyloidosis, but certain test results can help lead doctors to that diagnostic decision.

Alongside blood tests, doctors may use other tests that detect amyloid deposits — including urine tests, bone marrow biopsies, and tissue samples or biopsies — to diagnose the condition conclusively.

Complete Blood Count

A full blood count, also known as a complete blood count (CBC), is a standard blood test used to determine the levels of different types of blood cells in the body, including red blood cells, white blood cells, and platelets. Although CBC numbers do not determine whether a person should be diagnosed with amyloidosis, they do help rule out other potential causes of a person’s signs and symptoms.

Additionally, some amyloidosis treatments can change the number or quality of blood cells produced by your bone marrow. Doctors may order regular CBCs to monitor cells in your body throughout treatment.

Serum Protein Electrophoresis

Proteins called immunoglobulins act as antibodies in the blood. Paraproteins are abnormal immunoglobulins that occur in amyloidosis. The serum protein electrophoresis (SPEP) test examines your blood for these paraproteins. Certain types of amyloidosis can result in high levels of paraproteins, so the results of a SPEP test can help doctors better understand what is going on in a person’s body.

That said, the presence of paraproteins is not enough, in and of itself, to diagnose amyloidosis. Doctors must consider these results in the context of your symptoms and test results.

Serum Free Light Chain Assay

A serum free light chain (SFLC) assay tests for the presence of immunoglobulins in the blood. Immunoglobulin light chains are parts of these proteins that usually bind to another part, called heavy chains, to produce effective protein strands. When the light chains do not bind, it indicates a problem with your plasma cells, which may indicate AL amyloidosis.

The SFLC assay determines the number of free light chains in the blood. This test may not only help with diagnosis; it can also help doctors monitor the condition over time. If the numbers remain stable, a person’s amyloidosis is not getting worse. If the numbers improve, the person is likely responding well to medication or other treatments. An elevated number of free light chains may indicate the need to increase medication dosage or try a new treatment.

Kidney Function Tests

Since amyloidosis often affects the kidneys, doctors may check your renal (kidney) function during the diagnostic process. Although reduced kidney function alone will not indicate a diagnosis of amyloidosis, it can be one clue as to what is going on with your body.

If you have been diagnosed with amyloidosis, your doctor will want to monitor your kidney function continuously and carefully. You will likely need regular blood tests to make sure that your renal function is not deteriorating. Specifically, your doctors will look at the levels of creatinine and urea in your blood. Having high levels of these substances can indicate that your kidneys may not be working as well as they should.

Liver Function Tests

Similarly, your doctor may want to monitor your liver function if you’ve been diagnosed with amyloidosis. Doctors may look for the presence of alkaline phosphatase in your blood. High levels of alkaline phosphatase may indicate amyloidosis that affects the liver.

Heart Function Tests

The heart is another organ frequently affected by amyloidosis. To monitor your cardiac (heart) function, your doctor will likely test your blood for one or more of several cardiac biomarkers. These biomarkers include troponin T or troponin I, as well as brain natriuretic peptide (BNP) or NT-proBNP (which stands for N-terminal pro-BNP).

Some doctors and labs will measure all of these biomarkers, while others will choose to use one or two to be representative of overall heart health. Once again, these tests are not definitive — they offer a single clue as to whether you should be diagnosed with amyloidosis. They can also help your physician monitor your heart function over time to ensure that you do not start experiencing heart failure.

Genetic Tests

Certain genetic patterns can predispose a person to develop amyloidosis. If it seems likely that you have amyloidosis and doctors want to determine what type you have, they may examine a sample of your blood for genes such as transthyretin or fibrinogen.

Because these genes only create a predisposition for amyloidosis, their presence is insufficient to make a diagnosis. However, if you have other signs and symptoms of amyloidosis and these genes are present, it may point your doctors toward an amyloidosis diagnosis.

Find the Support You’ve Been Looking For

If you or someone you love has been diagnosed with amyloidosis, it’s easy to feel frustrated or overwhelmed. No matter what you’re feeling, people at MyAmyloidosisTeam — the social network for those diagnosed with amyloidosis and the people who care for them — will understand what you’re going through.

Have you had blood tests for amyloidosis? Share your experience in the comments below or by posting on MyAmyloidosisTeam.