Persistent hyponatremia and inappropriate antidiuretic hormone secretion in children with extensive burns.

Three children aged 2 1/2 to 5 1/2 yr, with burns covering 30%--45% of body surface area, developed hyponatremia and serum hypotonicity on the 5th--6th day following the burn injury. The hyponatremia persisted for 10--15 days. During this period, all three passed inappropriately concentrated urines. One child also demonstrated marked and inappropriate thirst. All three children demonstrated persistent respiratory alkalosis, which appeared and disappeared concomitantly with the hyponatremia. There were no signs of dehydration, and plasma volumes, measured in two children, were normal to high. These children are believed to show evidence of inappropriate antidiuretic hormone (ADH) secretion. In the absence of those conditions known to produce this syndrome, it is postulated that in these children it may have resulted from prolonged pain, anxiety, and/or pyrexia.