Post-operative hyponatremia in patients with pituitary adenoma: post-operative management with a uniform treatment protocol.

This study is a retrospective analysis of hyponatremia after transsphenoidal surgery in patients with pituitary adenoma. We evaluated (i) the incidence of post-operative hyponatremia (serum Na levels ≤ 135 mEq/L) and the emergence of hyponatremic symptoms, and assessed (ii) the risk factors under a uniform protocol of i.v. infusion with steroid and electrolyte fluid. We examined 88 consecutive operated patients (female: 60; male: 28) with pituitary adenoma. Apart from reconfirming the effects of the purported risk factors, we focused on the degree of serum Na decline on post-operative hyponatremia. Although remained stable during early post-operative period (4 days after surgery), the serum Na levels subsequently decreased after post-operative day 4 in 81 of 88 cases (92.0%). Of 88 patients, 27 (30.7%) and 9 (10.2%) cases suffered from hyponatremia, and developed hyponatremic symptoms. Interestingly, the degree of serum Na levels decline (from pre-operative levels) indicated a useful independent risk factor for monitoring hyponatremic symptoms (p = 0.006) and the degree of decline tended to be greater in elder patients (> 60 years) (p = 0.0346). Serum Na levels should be monitored from, at least, post-operative day 7 to detect early development of hyponatremia. Special attention and recovery effort should be given to elder patients with marked serum Na level decline after surgery.