R TAN 1,2, N RAO 1,2,3,4, C HORWOOD 5, G PASSARIS 1, R JUNEJA 1,2

1Renal Unit, Flinders Medical Centre , Bedford Park, Australia, 2College of Medicine and Public Health, Flinders University, Bedford Park, Australia, 3Renal Unit, Lyell McEwin Hospital, Elizabeth Vale , Australia, 4Adelaide Medical School, University of Adelaide, Adelaide , Australia, 5Department of Clinical Epidemiology, Flinders Medical Centre, Bedford Park, Australia

Aim: To determine whether symptomatic recurrent nephrolithiasis leads to progressive loss of kidney function.

Background: Nephrolithiasis is becoming more prevalent worldwide. There is limited published Australian data regarding worsening kidney function in patients with recurrent nephrolithiasis

Methods: Adults who presented to the Emergency Department at least twice with symptomatic and radiologically confirmed nephrolithiasis between 1st January 2005 to 31st December 2017 were retrospectively recruited. Baseline demographics, serum creatinine and stone characteristics were collected in December 2019. Primary endpoint was the change in glomerular filtration rate (GFR) between baseline and at the time of data collection. Secondary endpoints include GFR slope defined as the mean rate of change in GFR from baseline to the end of the study period.

Results: 240 patients had recurrent symptomatic nephrolithiasis. Median follow-up was 5.4 years. The median age of first acute presentation was 51.6 years old and the median baseline serum creatinine (bsCr) was 85.5umol/L. 17.5% (n=42) had worsening GFR, with the average change in GFR of -8.64 ml/min/1.73m² per year. Four patients progressed to ESKD requiring haemodialysis. 14.5% (n=35) had calcium oxalate stones. Univariate analysis showed older patients (p < 0.001), more symptomatic stone episodes (p < 0.001) and non-calcium containing stones (p < 0.001) were strongly associated with deteriorating kidney function. Age (p = 0.002) and number of acute stone episodes (p = 0.011) were significant predictive factors when unadjusted to co-morbidities in multivariate linear regression analysis. Average mean GFR slope was -2.83ml/min/1.73m2 per year.

Conclusions: Recurrent symptomatic nephrolithiasis is associated with loss of kidney function. Older patients, increased episodes of symptomatic nephrolithiasis with non-calcium containing nephrolithiasis were strongly associated with worsening kidney function.



Dr Rachel Tan is a Renal Fellow at the Royal Adelaide Hospital. She obtained her FRACP (Nephrology) in November 2020. Her interests include haemodialysis, amyloid and stone related kidney disease and country health.

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