<prompt> New born 7 days old with vomiting and dehydration clinical examination was normal except for hyperpigmentation of nipple. Electrolytes Na: 120 meq. K: 9 meq. mostlikelydiagnosis -Primary hypothyroidismCong, adrenal hyperplasiaPanhypopituitarismPyloric stenosis  <response>: Congenital adrenal hyperplasia due to defect in CYP21A2 is suggested by episodes of acute adrenal insufficiency with hyponatremia , hyperkalemia , dehydration vomiting Harrison 17 pg 2267 