Ans. is 'a' i.e., Diarrhoea Hyponatremia o Hyponatremia is defined as serum concentrationof Na+ < 130 meq/L. o Hyponatremia causes a decrease in the osmolality of ECF. Because the intracellular space then has a higher osmolality, water Inevitably moves from the extracellular to intracellular space. o Increase in intracellular water causes cell to swell. o Although cell swelling is not problematic in most tissues, it is potentially dangerous in the brain because it is contained in the fixed shell the skull. o As brain cells swell. there is an increase in ICT. So brain cells swelling is responsibe for most of the symptoms of hyponatremia. Anorexia, nausea & vomiting Headache Drowsiness Convulsions Coma Circulatory failure and hypotension o Hyponatremia can also cause muscle cramp and weakness. Central pontine myelinosis is classically associated with overlay rapid correction of hyponatremia.