Renal amyloidoses are a group of rare misfolding protein diseases caused by the deposition of a precursor protein in the kidney as insoluble amyloid fibrils, causing renal damage and dysfunction that can progress to end-stage renal failure requiring dialysis. This heterogeneous group includes commoner diseases as light chain (AL) and reactive (AA) amyloidosis as well as rarer entities as hereditary renal amyloidosis. Differential diagnosis is mandatory to avoid therapeutic errors and requires amyloid typing on tissue biopsy and, in selected cases, DNA analysis. In AL and AA amyloidosis, biomarkers are well-established tools that help clinicians in diagnosis, prognosis assessment and evaluation of treatment efficacy, highlighting the important role of the clinical laboratory in the management of these rare diseases. In AL amyloidosis, the identification of the monoclonal protein requires the combination of electrophoresis, immunofixation of both serum and urine, and serum free light chain (FLC) assessment. Severity of renal involvement and risk of progression to dialysis are predicted at diagnosis by 24h-proteinuria and estimated glomerular filtration rate (eGFR). Treatment efficacy is assessed with monoclonal protein studies, including serum FLC measurement; hematologic response can result in improvement of renal damage, evaluated by improvements in 24h-proteinuria and eGFR from baseline. In AA amyloidosis, a periodical evaluation of serum amyloid A (SAA) serum concentration reflects the activity of the underlying inflammatory disease and evaluates the efficacy of treatment. The severity of renal involvement can be assessed at diagnosis with 24h-proteinuria and eGFR. Only few data on prognostic markers are available on other types of renal amyloidosis.
ASJC Scopus subject areas
- Clinical Biochemistry
- Medical Laboratory Technology
- Biochemistry, medical