Prevalence Of Distal Renal Tubular Acidosis In Patients With Calcium Phosphate Urolithiasis Using Furosemide Test

Introduction: Adults with distal renal acidosis (DRTA) commonly present urolithiasis and alkaline pH (>6). Calcium phosphate is the most common urolithiasis related with DRTA. The main objective of our study is to determine DRTA prevalence in patients with calcium phosphate lithiasis and alkaline pH (>6) using the furosemide test.Materials: We selected 40 patients, 17 men and 23 women, between 18 and 65 years old with calcium phosphate lithiasis and alkaline urine pH (>6) treated in our department. Age, sex, urolithiasis localization (unilateral or bilateral) and side effects by furosemide test were collected. We analysed sex and urolithiasis location with chi-squared test, age was analysed with T-test. We considered stadistical significance p<0'05. We performed the furosemide test for the DRTA diagnosis. It consists in the administration of 40 mg of furosemide orally. We performed a urine pH test before the furosemide administration to verify a urine pH higher than 6. In the following 3 hours after the furosemide administration we performed a urine pH test to each micturition. We considered a urine pH higher than 6 in all the urine tests diagnostic of DRTA.Results: 15 patients (37'5 %) were positive for DRTA with furosemide test (Figure 1). The mean age in DRTA group was 40,73 years, in the other group was 51,12 years, statistical significance was found (p<0'001) (Figure 2). All the patients (15) in the DRTA group presented with bilateral urolithiasis (p<0'001) (Figure 3). There were 10 women and 5 men in the DRTA group, no statistical significance was found (p<0'342). No side effects were reported with furosemide test.Conclusion: We conclude that the DRTA prevalence in our sample is 37'5% using furosemide test and the furosemide test is save. Our data suggest that bilateral urolithiasis and young age could be considered risk factors for DRTA.