Clinical course and prognosis of tubulopathies characterized by metabolic alkalosis in children

Purpose: Bartter and Gitelman syndromes are rare inherited tubulopathies characterized by hypokalaemic, hypochloraemic metabolic alkalosis. Three phenotypes exist in BS; antenatal (aBS), classical (cBS) and mixed type. Also, BS is classified genotypically into five types as SLC12A1 (BS I), KCNJ1 (BS II), CLCNKB (BS III), BSND (BS IV) and CASR (BS V). It is aimed to clarify the frequency of the phenotypic and genotypic subgroups, clinical features, long-term management and prognosis of children diagnosed with BS and GS in this study. Material and methods: Twenty seven patients with BS and six patients with GS, who were followed-up between 2004 and 2020 in Department of Pediatric Nephrology, Çukurova University Faculty of Medicine, were included in our study. Results: Fifteen (55.5%) of the patients with BS were male and 2 (33.3%) of the GS patients were male. The mean age of diagnosis was 14.9 months (0.5- 84) in patients with BS and 158 months (84-192) in patients with GS. Fourty eight percent of BS patients had a history of polyhydramnios. Ten patients with BS had CLCNKB, 3 patients had SLC12A1, 1 patient had BSND, 1 patient had CLCNKA, and 6 patients with GS had SLC12A3 genetic mutations. Growth retardation was found in 81.8% of patients with aBS, 68.7% of patients with kBS and mixed type, and 50% of patients with GS. Chronic kidney disease (CKD) stage 3 was detected in 14% of patients with BS at the time of diagnosis, while the rate of patients with CKD stage 3 and above at the last follow-up was 25.9%. Estimated glomerular filtration rates (eGFR) of patients with GS were normal at the time of diagnosis and at the last follow-up. eGFR values were found to be statistically significantly lower in patients with aBS than in patients with kBS and GS in the last follow-up. Conclusion: Patients with BS and GS may have a different clinical course due to the underlying genetic mutation. Since BS and GS require life-long treatment, treatment compliance is important to prevent advanced stage CKD. Key words: Bartter Syndrome, Childhood, Gitelman Syndrome, Metabolic alkalosis