Renal Amyloidosis from Initial Presentation and Beyond

The kidneys are among the main organs affected by amyloidosis, with kidney dysfunction contributing to significant morbidity and mortality. In the United States, light chain amyloidosis (AL) is the most common cause of renal amyloidosis (81%-86%), with the kidneys affected in ≤80% of patients with AL.

Patient presentations of renal amyloidosis vary by amyloid type and location, amount of amyloid deposition within the kidney, and the extent of extrarenal involvement. Proteinuria is the most common manifestation of renal amyloidosis, ranging from minimal to massively nephrotic, depending on the degree of glomerular involvement. Patients with AL often present with a high degree of proteinuria, with >65% of patients experiencing nephrotic syndrome, as AL commonly affects the glomerulus. In addition, >75% of patients with renal amyloidosis present with peripheral edema due to nephrotic syndrome, renal failure, heart failure, or a combination of these conditions. Hypotension may also be seen in these patients, especially in those with autonomic dysfunction or advanced heart failure, and it can lead to progressive renal dysfunction.

Renal amyloidosis should be included in the differential diagnosis of proteinuria, especially nephrotic syndrome, with the level of suspicion elevated in the presence of heart failure, gastrointestinal symptoms, and neuropathy. Testing for renal amyloidosis depends on patient history and presentation, with definitive diagnosis of renal amyloidosis made by renal biopsy.

Management of renal amyloidosis generally includes amyloid-targeted therapies and supportive care, with goals of reducing amyloid burden, limiting further kidney injury, and maintaining or improving renal function. Loop and/or thiazide diuretics are often used for volume control, along with salt and fluid restriction. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can be used to reduce proteinuria unless contraindicated. Renal function, proteinuria, blood pressure, and volume status should be monitored. Renal response is measured by change in renal function (serum creatinine, estimated glomerular filtration rate [eGFR]) and proteinuria. Patients with renal amyloidosis may develop chronic kidney disease (CKD); care should be taken to manage CKD-related complications. End-stage renal disease (ESRD) can be treated with dialysis or renal transplantation.

The course and prognosis of renal amyloidosis vary by the type of amyloidosis, although progressive deterioration in renal function is expected in most patients. Patients with renal AL tend to have a more rapid decline in renal function than other types and, consequently, ESRD occurs in ~25% of these patients. Proteinuria >5 g/day and eGFR <50 mL/min at baseline were found to be the best independent predictors of ESRD. Patients who reached ESRD had 2.97 times higher risk of death compared with those who did not. Achievement of renal response has been associated with improved renal function and patient survival.

Source

Gurung R, Li T. Renal amyloidosis: presentation, diagnosis, and management. Am J Med. 2022;135(suppl 1):S38-S43.

Related Items

Amyloidosis News
Subscribe to Amyloidosis News

Stay up to date with Amyloidosis News by subscribing to receive the free AMN e‑Newsletter.