At eight months of age, our patient was diagnosed as having classic BS based on the following findings: failure to thrive, metabolic alkalosis (pH 7.423; HCO3-, 33.6mmol/L; base excess, +8.2), hypokalemia (2.9mEq/L), and hyperactive renin-aldosterone system (plasma renin activity (PRA), 270ng/mL/h; normal value for his age, 2.58 ± 1.41ng/mL/h); aldosterone level, 850pg/mL (2,358pmol/L; normal value for his age, 173.7 ± 96.3pg/mL). Here, REN is linked to Failure to thrive.