title: Hyponatremia after transsphenoidal surgery for hypothalamo-pituitary tumors.
abstract: Transient diabetes insipidus is a well-known complication after transsphenoidal surgery (TSS). On the other hand, transient hyponatremia has been reported as being a delayed complication of TSS. Transient hyponatremia has been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but the details of hyponatremia have not been clarified. In the present study, we retrospectively reviewed 110 consecutive patients (39 males and 71 females, age 9-80 years) operated on transsphenoidally for pituitary and hypothalamic tumors. We investigated the frequency, time of onset, duration of hyponatremia after TSS, and analyzed possible factors associated with it. A postoperative sodium concentration <135 mEq/l was observed in 29 (26%) patients. Five patients were excluded from this study because their hyponatremia could be due to either overdose of desmopressin or SIADH for meningitis. Therefore, we investigated 24 (22%) patients with hyponatremia in this study. The sodium levels in the patients with hyponatremia ranged from 110 to 134, with a mean of 126.2 +/- 5.3 mEq/l. Hyponatremia was observed on average on postoperative day 9.5 +/- 2.4, the serum sodium levels normalized within 3.8 +/- 1.7 days. Hyponatremia occurred in patients with non-functioning pituitary adenoma (26%, 11/42), Rathke's cleft cyst (29%, 5/17), prolactinoma (31%, 4/13) and acromegaly (15%, 4/27). 18 patients (75%, 6/24) who developed hyponatremia had macrotumor (>10 mm), and 6 patients (25%, 6/24) had microtumor. The plasma arginine vasopressin (AVP) levels in the patients with hyponatremia ranged from 0.21 to 2.1, with a mean of 0.79 +/- 0.46 pg/ml, and the levels were inversely correlated with plasma osmolality (r = -0.80, p = 0.002). The urine to plasma osmolality ratios were >1. All the patients received appropriate hormonal replacement, including hydrocortisone. These data showed that postoperative hyponatremia after TSS was not rare, and the hyponatremia was mainly associated with SIADH. As the hyponatremia could be a life-threatening complication, all patients should be screened for serum electrolytes after TSS.
authors.affiliation: Department of Medicine, Institute of Clinical Endocrinology, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Sata
authors.forename: Naomi
authors.initials: N
authors.lastname: Hizuka
authors.forename: Takakazu
authors.initials: T
authors.lastname: Kawamata
authors.forename: Tomokatsu
authors.initials: T
authors.lastname: Hori
authors.forename: Kazue
authors.initials: K
authors.lastname: Takano
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001127:Arginine Vasopressin / Q000097:blood; D002648:Child; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000209:etiology*; D007016:Hypophysectomy / Q000009:adverse effects*; D007029:Hypothalamic Neoplasms / Q000601:surgery; D007177:Inappropriate ADH Syndrome / Q000150:complications / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D010911:Pituitary Neoplasms / Q000601:surgery; D011183:Postoperative Complications; D012189:Retrospective Studies; D013100:Sphenoid Bone / Q000601:surgery*
chemical_list: D001127:Arginine Vasopressin