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Amyloidosis — misfolded proteins deposit in organs, most commonly the kidneys (AL and AA types). Nephrotic syndrome, diagnosis, and the treatments that target the source.
Evidence reviewed & updated: 2026-08 — reflects the latest published trials and guidelines.
Amyloidosis is a group of diseases where misfolded proteins deposit in organs as amyloid fibrils — and the kidney is one of the most commonly affected organs. The two main kidney forms: AL amyloidosis (from a plasma cell disorder producing antibody light chains) and AA amyloidosis (from chronic inflammation). Kidney involvement typically presents as heavy proteinuria and nephrotic syndrome.
AL amyloidosis is caused by a clone of plasma cells producing misfolded antibody light chains that deposit as amyloid. It's the most common form and is a cancer-adjacent disease (related to myeloma) — treated by attacking the plasma cells. AA amyloidosis comes from chronic inflammation — longstanding rheumatoid arthritis, untreated TB, or chronic infections — where serum amyloid A protein misfolds.
Both deposit in the glomeruli, causing proteinuria and nephrotic syndrome; kidneys are typically normal-sized or ENLARGED (unlike shrinking CKD).
Kidney signs: heavy proteinuria, edema, sometimes hypertension. Organ clues elsewhere: carpal tunnel syndrome (bilateral — a classic early sign), stiff heart failure with normal EF, peripheral neuropathy, macroglossia (large tongue), periorbital purpura, and easy bruising.
Diagnosis: serum free light chains (AL), urine immunofixation, and tissue biopsy (kidney, or fat pad/rectal — Congo red positive with apple-green birefringence), then typing to distinguish AL from AA.
AL amyloidosis is treated at the plasma-cell level: modern regimens combine daratumumab with bortezomib/cyclophosphamide/dexamethasone (Dara-VCD is now standard), with autologous stem cell transplant in eligible patients. Response is measured by light-chain levels and organ improvement — proteinuria falls as the clone is suppressed.
AA amyloidosis is treated by eradicating the underlying inflammation (biologics for rheumatoid, anti-TB therapy, etc.) — proteinuria often improves. Supportive care: diuretics for edema, ACEi/ARB for proteinuria, and heart-failure management. Outcome depends on organ involvement and treatment timing — cardiac involvement dominates prognosis in AL.
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