Clinical Characterisation and Outcomes in Adults with Renal Amyloidosis Confirmed by Kidney Biopsy in Colombia

Background: Renal amyloidosis is a rare disease that progresses over time and can be fatal, with one-third of patients requiring dialysis. There is currently a paucity of literature about monoclonal gammopathy with renal significance in Latin America. The objective of this study was to provide a comprehensive description of the demographic, clinical and paraclinical characteristics and outcomes of patients with renal amyloidosis. Methods: This is a multicentre, retrospective study. The study included patients with renal amyloidosis, confirmed by renal biopsy, within the Keralty Bogotá network and San Ignacio University Hospital between the 1st of January 2013 and the 31st of August 2021. The clinical records were reviewed to identify eligible patients, and the medical records were analysed to ascertain the variables of interest. Results: The study cohort comprised a total of 37 patients. The mean age of the participants was 59.4 years (SD 11.2), with a female predominance of 23/37 (62.2%). Prevalent clinical manifestation at the time of admission was nephrotic syndrome (35/37, 94.6%), followed by nephritic syndrome (2/37, 5.4%). The mean proteinuria was 5.72 g/24 hours (interquartile range (IQR) 4.12 g/d). The most prevalent form of amyloidosis was associated with the monoclonal immunoglobulin AL, accounting for 29 out of 37 cases (87.9%). The mean serum creatinine at diagnosis was 2.23 mg/dL (standard deviation 2.09 mg/dL). The mean serum albumin level was 2.54 g/dL (SD 1.11 g/dL). The most prevalent additional health condition was hypertension, affecting 15 out of 37 patients (40.5%). The most frequently employed regimen was cyclophosphamide, bortezomib and dexamethasone, which was utilized in 19 out of 37 patients (51.3%). Most patients who received this regimen achieved a hematological partial remission. Renal replacementtherapy was initiated in 13 patients (36.1%) due to the progression of chronic kidney disease. Conclusion: This study describes a cohort of 37 patients with renal amyloidosis, in which the AL type was observed with a higher frequency than previously reported in the literature. The main manifestation was nephrotic syndrome. Understanding of the clinical course and the development of more robust early detection strategies will facilitate enhanced hematological and renal responses in patients.