Bartter syndrome (BS) is a rare renal tubular disorder presenting with 
hypokalemic metabolic alkalosis, which is classified into five types. KCNJ1 
mutations usually cause the neonatal form of BS, type II BS (OMIM 241200). 
However, this report concerns a female patient with a novel, compound 
heterozygous KCNJ1 mutation that causes late-onset BS. The unique clinical 
findings of this case include persistently elevated 1,25(OH)(2) vitamin D 
levels, possibly due to increase prostaglandin E(2) levels, and medullary 
nephrocalcinosis. Treatment with COX-2 inhibitors resolved her hypercalciuria 
and improved her height and weight; renal function remains stable and there is 
no progression of nephrocalcinosis.