Introduction: Who Should Seek Diagnostic Testing

Primary amyloidosis, also known as AL amyloidosis (where “AL” stands for amyloid light chain), presents a diagnostic challenge because its symptoms are often non-specific and can easily be mistaken for signs of aging or other more common health problems. People who experience unexplained and persistent symptoms should consider seeking medical evaluation, particularly when multiple symptoms occur together.^[1]

If you notice serious fatigue that doesn’t improve with rest, unexplained shortness of breath, swelling in your ankles and legs that persists, or numbness and tingling in your hands or feet, these warrant medical attention. Other concerning signs include unintentional weight loss, an enlarged tongue, skin changes such as easy bruising or purplish patches around your eyes, or difficulty swallowing.^[2][4]

The journey to receiving a correct diagnosis can be frustratingly long. Research shows that almost one-third of people with this condition will visit more than five different physicians before being properly diagnosed. Around 70 percent of patients do not receive their diagnosis until more than a year after symptoms first begin, and up to 20 percent may not be correctly diagnosed for two years or longer.^[15]

Early medical consultation is crucial. Research demonstrates that seeking medical help as soon as symptoms appear can lead to an earlier and more accurate diagnosis. This is especially important because AL amyloidosis progresses over time, and early treatment can help prevent or slow further organ damage.^[4][18]

People who already have certain blood-related conditions should be particularly vigilant. AL amyloidosis is closely related to other plasma cell disorders, including multiple myeloma. About 10 to 15 percent of people with multiple myeloma will also develop AL amyloidosis. Anyone diagnosed with multiple myeloma, Waldenström’s macroglobulinemia, non-Hodgkin lymphoma, or other plasma cell disorders should be aware of the possibility of developing AL amyloidosis and report any new symptoms promptly.^[5][3]

Classic Diagnostic Methods

Diagnosing AL amyloidosis requires a multi-step approach that combines different types of tests. The diagnostic process aims to answer three critical questions: Is amyloid present in the body? What type of amyloid protein is causing the deposits? And which organs have been affected by the disease?^[8]

Initial Laboratory Tests

The first step in diagnosing AL amyloidosis typically involves blood and urine tests. These tests look for abnormal proteins that might indicate the presence of this condition. Healthcare providers will analyze both blood and urine samples to detect abnormal light chains, which are the proteins that form amyloid deposits in AL amyloidosis.^[8][4]

Blood tests include a complete blood count (CBC) with differential and chemistry panel to assess overall health and organ function. A particularly important test is the serum free light chain assay, which measures the levels of specific light chain proteins circulating in the blood. The ratio between different types of light chains can provide valuable clues about whether AL amyloidosis might be present.^[12]

Urine testing involves collecting either a single urine sample or a 24-hour urine collection to perform immunofixation electrophoresis. This test can detect abnormal proteins in the urine, sometimes called Bence Jones protein, which represents light chains being filtered through the kidneys. The presence of these proteins supports the diagnosis of a plasma cell disorder that could be causing AL amyloidosis.^[5][2]

Tissue Biopsy: The Gold Standard

While blood and urine tests can suggest the presence of abnormal light chains, a tissue biopsy is essential to confirm that amyloid deposits are actually present in the body. A biopsy involves taking a small sample of tissue and examining it under a microscope to look for the characteristic appearance of amyloid proteins.^[4][5]

One of the simplest and least invasive ways to obtain tissue for testing is through an abdominal fat pad aspiration. This procedure uses a fine needle to extract a small sample of fat tissue from the belly area. Because fat tissue commonly contains amyloid deposits in people with systemic AL amyloidosis, this test can often provide the diagnosis without requiring more invasive procedures.^[5][2]

Another common biopsy site is the bone marrow. A bone marrow biopsy can both detect amyloid deposits and examine the plasma cells to see if they are abnormal. This procedure typically involves inserting a needle into the hip bone to extract a small sample of bone marrow. Healthcare providers usually perform this test because it provides information about both the presence of amyloid and the underlying plasma cell disorder causing the disease.^[4][2]

In some cases, doctors may need to perform biopsies of specific organs that appear to be affected by the disease. For example, if symptoms suggest heart or kidney involvement, a biopsy of these organs might be necessary to confirm amyloid deposits and assess the extent of damage. A rectal mucosa biopsy is another option that some centers use because the rectum is easily accessible and often contains amyloid deposits.^[2][4]

Identifying the Type of Amyloid

Once amyloid deposits have been found, it’s crucial to determine exactly what type of protein is forming these deposits. This is important because different types of amyloidosis require completely different treatments. Several techniques can identify the specific protein involved, often performed directly on the biopsy tissue sample.^[8]

Special staining methods help identify amyloid under the microscope. When viewed with specific dyes, amyloid deposits appear in characteristic colors. Laboratories use techniques that can distinguish AL amyloid (made of light chains) from other types such as ATTR amyloid (made of transthyretin protein) or AA amyloid (made of serum amyloid A protein).^[3]

Assessing Organ Involvement

After confirming AL amyloidosis, doctors need to determine which organs have been affected and how severely. This assessment guides treatment decisions and helps predict outcomes. Multiple types of imaging and functional tests are used for this purpose.^[2]

For the heart, an echocardiogram uses sound waves to create moving images showing how well the heart is pumping and whether the heart walls have become thickened due to amyloid deposits. An electrocardiogram (ECG) records the heart’s electrical activity and may show abnormal patterns that are characteristic of cardiac amyloidosis. Cardiac MRI can provide detailed images of heart structure and function and may reveal patterns specific to amyloidosis affecting the heart.^[8][4]

Nuclear imaging tests involve injecting tiny amounts of radioactive material into a vein, which then accumulates in certain tissues. In cardiac amyloidosis, specific tracers can bind to amyloid deposits in the heart, helping not only to confirm heart involvement but also to distinguish between different types of amyloidosis.^[8]

Kidney function is assessed through blood tests that measure creatinine and calculate the glomerular filtration rate (eGFR), which indicates how well the kidneys are filtering waste from the blood. Urine tests measure protein levels because kidney damage from amyloidosis often causes significant protein loss in the urine, a condition called nephrotic syndrome.^[2][4]

If nerve damage is suspected, doctors may perform an electromyography (EMG) test, which measures electrical activity in muscles and nerves. This can help identify peripheral neuropathy (nerve damage in the arms and legs) or problems with the autonomic nervous system, which controls automatic functions like blood pressure regulation.^[2]

Additional imaging studies such as abdominal ultrasound may be performed to check the liver and spleen for enlargement. If gastrointestinal symptoms are prominent, doctors might recommend an endoscopy to look directly at the digestive tract or take tissue samples from the stomach or intestines.^[2]

Diagnostics for Clinical Trial Qualification

When patients with AL amyloidosis are being considered for enrollment in clinical trials, they typically undergo additional specific tests beyond those used for standard diagnosis. Clinical trials have strict criteria to ensure that participants are appropriate for the experimental treatments being studied and can be safely monitored throughout the trial.^[13]

Measuring Disease Activity

Clinical trials often require precise measurements of how active the disease is. The difference between involved and uninvolved free light chains in the blood is a key measurement. This difference, sometimes called the dFLC or “difference in free light chains,” indicates how much abnormal light chain protein the plasma cells are producing. Trials typically require a certain minimum level of abnormal light chains to ensure that changes in these levels can be detected during treatment.^[13]

Bone marrow biopsies are usually required to confirm the presence of abnormal plasma cells and to determine the percentage of plasma cells in the marrow. Many clinical trials specify that patients should have less than 10 percent plasma cells in the bone marrow, which helps distinguish AL amyloidosis from multiple myeloma, where plasma cell percentages are typically higher.^[7]

Evaluating Organ Function for Trial Safety

Because treatments being studied in clinical trials may be intensive and can have significant side effects, trials have specific requirements regarding organ function to ensure patient safety. These eligibility criteria help protect participants from treatments that might be too risky given their current health status.^[13]

For heart function, clinical trials typically require a left ventricular ejection fraction (LVEF) above a certain threshold, often greater than 40 percent. The LVEF measures how much blood the heart pumps out with each beat, assessed through an echocardiogram or cardiac MRI. Trials also assess blood pressure, requiring that patients have stable readings that don’t drop too low when standing up, a condition called orthostatic hypotension that can be caused by amyloidosis affecting the nervous system.^[13]

Lung function may be tested through pulmonary function tests and oxygen saturation measurements. Some trials require that oxygen saturation be above 95 percent on room air and that diffusing capacity of the lungs for carbon monoxide (DLCO) be greater than 50 percent of predicted values. These tests ensure that patients have adequate lung function to tolerate treatment.^[13]

Kidney function is assessed through blood tests measuring creatinine and calculating the estimated glomerular filtration rate (eGFR). Many trials require an eGFR greater than 30 mL/min/1.73m², though some trials may accept patients requiring dialysis if they are otherwise suitable candidates. Liver function tests, including bilirubin levels, are also checked. Trials typically require that direct bilirubin be less than 2 mg/dL to ensure adequate liver function.^[13]

Performance Status Assessment

Clinical trials use standardized scales to assess how well patients can perform daily activities. The Eastern Cooperative Oncology Group (ECOG) performance status is commonly used, ranging from 0 (fully active) to 4 (completely disabled). Most clinical trials in AL amyloidosis require patients to have an ECOG performance status of 0 to 2, meaning they can care for themselves and are up and about for at least half of waking hours, though they may not be able to work.^[13]

Disease Staging

Several staging systems have been developed for AL amyloidosis, particularly to assess cardiac involvement, which is the most important factor affecting prognosis. The most widely used is the Mayo Clinic staging system, which uses blood levels of specific biomarkers related to heart function. These include troponin (a protein released when heart muscle is damaged) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) (a hormone released when the heart is under stress). The combination of these markers helps classify patients into different risk groups.^[7]

Clinical trials often use these staging systems to select appropriate participants. Some trials may only enroll patients with early-stage disease to test preventive approaches, while others focus on patients with more advanced disease who need more aggressive treatments. Understanding your disease stage can help you and your healthcare team identify which clinical trials might be most appropriate.^[7]

Age and Overall Health Considerations

Clinical trials often have age restrictions, though these vary depending on the specific trial. Some trials focus on younger patients who might be candidates for intensive treatments like autologous stem cell transplantation, while others specifically study treatments in older adults. Trials typically require patients to be at least 18 years old, with upper age limits often set around 70 years for more intensive treatments, though this is not universal.^[13]

Overall health status beyond the amyloidosis itself is also considered. Patients need to be healthy enough to travel to the trial site for regular monitoring visits, which may be frequent during the study. They should not have other serious medical conditions that might complicate interpretation of the trial results or make the experimental treatment too risky.^[13]