UKMLA PLAB AMC USMLE Prometric MCQ

8) A 6-week-old male infant is admitted to hospital with 10-15% dehydration. The serum
sodium is 160 mmol/l and the serum potassium is 3.3 mmol/l:

FFFTT

Comments:
The most likely cause of hypernatraemic dehydration in infants and children is infective
diarrhoea. This is likely to be bacterial if the stool contains blood. The skin may have a doughy
consistency in hypernatraemic dehydration. Rapid correction of the increased serum
osmolarity results in intracellular fluid accumulation, which may lead to cerebral oedema. This
can be avoided by slowly correcting the fluid depletion (over 24-48 hours) and ensuring that
the serum sodium is lowered at a rate of no greater than 10 mmol/l/24 hours.