<prompt> A 5-month old formula fed infant has been brought with complaints of watery diarrhoea of 2 days duration and irritability of one day duration.He had been receiving WHO ORS at home. Physical examination reveals a markedly irritable child with a rather doughy skin and rapid pulse.The most likely diagnosis is-MeningitisEncephalitisHyponatremic dehydrationHypernatremic dehydration  <response>: Ans. is d i.e., Hypernatremic dehydration o This child has i Irritability ii Doughy skin iii History of ORS taken at home o Irritability and doughy skin is seen in hypernatremic dehydration. o Hypernatremic dehydration occurs when fluid is given with more salts. o This child must have taken more ORS than fluid i.e., concentrated ORS. o About hyponatremic dehydration There is drowsiness not irritability Skin is dry inelastic not doughy. 