Renal Involvement as a Presenting Feature of Multiple Myeloma.

Renal involvement may be the presenting feature in a vast majority of patients with multiple myeloma and is one of the key for clinical manifestations of symptomatic multiple myeloma. The purpose of the study was to find out the pattern of renal involvement at the time of presentation of multiple myeloma and to explore its association with clinical, laboratory and pathologic features of these cases. This cross sectional study was conducted in the Department of Nephrology at Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from February 2016 to September 2017. Forty seven (47) patients of newly diagnosed multiple myeloma having renal involvement were included in the study. Multiple myeloma was diagnosed as per criteria proposed by the International Myeloma Working Group, 2003. Renal involvement was considered to be present when any one of proteinuria, microscopic haematuria, renal impairment or urinary tract infection (UTI) was found in the patient. Renal biopsy was done in suitable patients under ultrasound guidance after taking informed written consent. The pattern of renal involvement was detected and status of renal function was assessed and its clinical, laboratory and pathologic associations were analyzed. Data were managed by using computer based software, the Statistical Package for Social Sciences (SPSS) version 23 (IBM Corp.). Median age at presentation was 59 years with the range of 37-76 years. Female (53.2%) was slightly predominant than male (46.8%) and male to female ratio was 1:1.14. Renal impairment, microscopic haematuria, proteinuria, nephrotic range proteinuria, urinary Bence Jones protein and UTI were found in 70%, 19%, 79%, 25%, 19% and 17% of patients respectively. Median serum creatinine and proteinuria were 256μmol/l and 1.24gm/day. Hypercalcaemia and Bence Jones proteinuria were detected in 36% and 27% of patients respectively with renal impairment which were statistically significant. The precipitating factors for renal impairment were NSAIDs use (67%), hyperuricaemia (49%), hypercalcaemia (36%), dehydration (27%), UTI (18%) and no identifiable factor (3%). Dialysis was required in 15% new myeloma patient. Renal biopsy and histopathological examination revealed myeloma cast nephropathy (30%), amyloidosis (30%), glomerulosclerosis (chronic kidney disease) (20%), monoclonal immunoglobulin deposition disease (MIDD) (10%) and interstitial nephritis with fibrosis (10%). Renal involvement was a common and severe complication of multiple myeloma. Renal impairment was strongly associated with hypercalcaemia, NSAIDs use, hyperuricaemia, Bence Jones proteinuria etc.