An unusual cause of failure to thrive in a child.

Classic Bartter syndrome, depending on the severity, presents during childhood or adolescence as failure to thrive and may be incorrectly labelled as protein–energy malnutrition, particularly in children from a low socioeconomic stratum. We encountered a 5-year-old boy who was asymptomatic till the age of 3 years. Despite adequate dietary intake, he was admitted and managed in various hospitals as a case of protein–energy malnutrition. On evaluation, he had unusual features in the form of persistent hypokalaemia and polyuria leading us to suspect a renal tubular disorder. Treatment of the condition resulted in good weight gain and normalization of serum electrolytes.