Epidemiological, clinical and laboratorial profile of renal amyloidosis: a 12-year retrospective study of 37 cases

Background: Renal amyloidosis is one of the main differential diagnoses in the investigation of nephrotic proteinuria in adults, especially elderly patients. Objectives: The aim of this article is to contribute to international research with epidemiologic data of renal amyloidosis, given the lack of uniformity described in the literature. Patients and Methods: A retrospective study of 37 cases of renal amyloidosis diagnosed by kidney biopsy, between 2000 and 2011, considering epidemiological, clinical and laboratory data. Results: Subjects aged between 32 and 80 years. Of the 37 cases, 21 (56.8%) were diagnosed as non-light chain (non-AL) renal amyloidosis and 16 (43.2%) as light chain amyloidosis (AL). There was seen an increase in number of both AL and non-AL cases, with a slight predominance in non-AL. The mean 24-hour proteinuria was 5839.0 mg/day. Hematuria was present in 75% of patients. Hypertension was reported in 34% of patients. Acute renal failure, occurred in about 10% of patients, and chronic loss of renal function was present in about 5% at diagnosis. Conclusions: Renal amyloidosis is a disease of increasing incidence. The forms of clinical presentation proved to be variable, but the presence of proteinuria or nephrotic syndrome in elderly patients should always prompt the suspicion of renal amyloidosis and is a formal indication of renal biopsy.