Patients with Bartter syndrome types 1, 2 and 4 present at a younger age than classic Bartter syndrome type 3. They present with symptoms, often quite severe in the neonatal period. Patients with classic Bartter syndrome type 3 present later in life and may be sporadically asymptomatic or mildly symptomatic. The severe, steady-state hypokalemia in Bartter syndrome and Gitelman syndrome may abruptly become life-threatening under certain aggravating conditions. Clinicians need to be cognizant of such renal tubular disorders, and promptly treat at-risk patients.