A 2-year-old child presented with diarrhoea and failure to thrive, Blood examination shows – Na = 122,K – 6. He is most probably suffering from –

Na+ is 122 (hyponatremia). That means, there is salt losing enzyme deficiency, causing hyponatremia and hyperkalemia. 21 hydroxylase deficiency causes hyponatremia and hyperkalemia. 17α -hydroxylase and 11-β -( hydroxylase deficiency cause hypernatremia and hypokalemia. Butter syndrome causes excessive loss of Na+, K+ and Cl causing severe hypokalemia and hyponatremia.