Inappropriate secretion of antidiuretic hormone in a postsurgical pediatric population.

Twenty-four pediatric patients undergoing corrective posterior spinal fusion surgery for idiopathic scoliosis were studied to determine the frequency with which the syndrome of inappropriate antidiuretic hormone secretion (SIADH) developed. We measured arterial blood gases, serum and urine electrolytes and osmolalities, CVP, and urine output during and after surgery. The 20 patients receiving hypotonic iv salt solution in the immediate postoperative period experienced a significant drop in serum sodium values (6.2 +/- 2.9 mEq/L) and 5 (25%) developed SIADH as diagnosed by routine laboratory procedures. Four patients were treated with iv isotonic salt solution. No patient developed hyponatremia (serum Na+ less than 130 mEq/L) and the decrease in serum sodium (3.0 +/- 0.8 mEq/L) was not statistically significant. We conclude that SIADH occurs commonly in patients undergoing corrective vertebral surgery and that vigilant attention must be paid to their fluid and electrolyte management in the postoperative period.