Healthy volunteers
Not accepted
1. Main inclusion criteria: Pediatric OPD, age \< 18 y/o.
2. Main exclusion criteria: Acute renal failure, edema, muscular dystrophy, pleural effusion, ascites, malnutrition, neurogenic bladder, heart failure and ketoacidosis. And taken cimetidine or trimethoprim, and accepted renal replacement therapy.
