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Hidden Clues in Urine: How Does Bence Jones Protein Reveal the Truth about AL Amyloidosis?
AL amyloidosis, also known as primary amyloidosis, is the most common form of systemic amyloidosis. The disease is caused by a malfunction of antibody-making cells, leading to the production of abnormal protein fibers that are composed of antibody components called light chains. When these light chains aggregate, amyloid deposits form, which can cause severe damage to a variety of organs. The abnormal light chains found in urine are called Bence Jones proteins.
Symptoms and signs
AL amyloidosis can affect a variety of organs and therefore may cause a variety of symptoms. The most common non-specific symptoms include fatigue and weight loss. The kidneys are often affected, with 60 to 70 percent of people experiencing kidney damage. Possible symptoms include fluid retention, swelling and difficulty breathing.
Other kidney-related symptoms include protein loss in the urine, low albumin levels in the blood, and secondary hyperlipidemia (nephrotic syndrome).
About 70% to 80% of patients with AL amyloidosis involve the heart, and cardiac damage is the main cause of death. Complications of heart disease include heart failure and arrhythmias. Initial cardiac involvement may show low-voltage electrical rhythms, concentric left ventricular hypertrophy, and diastolic dysfunction on the electrocardiogram.
Cause
AL amyloidosis is caused by the deposition of abnormal antibody free light chains. These abnormal light chains are produced by monoclonal plasma cells, and although AL amyloidosis does not necessarily accompany the diagnosis of other diseases, it is often associated with other plasma cell disorders, such as multiple myeloma and Waldenström macroglobulinemia.
Among patients with multiple myeloma, approximately 10% to 15% will develop overt AL amyloidosis. The disease is never passed on to the next generation.
Diagnosis
Diagnosing AL amyloidosis requires identifying amyloid deposits in tissue samples and confirming the presence of plasma cell disease. Blood and urine tests can be used to identify the light chains that make up amyloid deposits, but accurate diagnosis still requires taking a sample of amyloid deposits.
Treatment
Currently, the most effective treatment is autologous bone marrow transplantation and stem cell rescue, but many patients are unable to withstand this treatment due to their frailty. Other treatments include using chemotherapy similar to that used in multiple myeloma, targeting plasma cells that produce misfolded light chain proteins.
The preferred therapies are cyclophosphamide, bortezomib, and dexamethasone (CyBorD), especially for patients who are not eligible for stem cell transplantation.
Prognosis and epidemiology
AL amyloidosis is a rare disease, with 1,200 to 3,200 new cases reported each year in the United States and between 500 and 600 in the United Kingdom. About two-thirds of patients are male, and less than 5% are under 40 years old.
AL amyloidosis is a complex and widely affected disease, and its diagnosis, treatment, and future prognosis are full of unknowns. Will the development of such diseases trigger greater public attention to improve understanding and early detection?
