<prompt> 2 year old child presented with diarrhoea and failure to thrive, Blood examination shows - Na 122, K - 6. He is most probably suffering from ?Bater syndrome214x Hydroxylase deficiency11-p Hydroxylase deficiency,17-a Hydroxylase deficiency  <response>: Ans. is b i.e., 21-a Hydroxylase deficiency o Na is 122 hyponatremia. That means, there is salt losing enzyme deficiency, causing hyponatremia and hyperkalemia. o 21 hydroxylase deficiency causes hyponatremia and hyperkalemia. 17a-hydroxylase and 11beta hydroxylase deficiency cause hypernateremia and hypokalemia. 