P ostoperative hypopituitarism and hor- monal recovery are well-known conse- quences of transsphenoidal pituitary ade- noma removal. In most reports, the rate of new long-term pituitary failure is less than 10% (11, 24, 37, 38), with higher rates reported in cases of pituitary apoplexy and reoperations for Cushing’s disease (41, 43). Although most transsphenoidal surgical series cite rates of new hypopituitarism, there have been few sys- tematic analyses looking at rates across differ- ent tumor types and potential predictors of NEUROSURGERY VOLUME 63 | NUMBER 4 | OCTOBER 2008 | 709 CLINICAL STUDIES Nasrin Fatemi, M.D. Brain Tumor Center, John Wayne Cancer Institute at Saint John’s Health Center, Santa Monica, California Joshua R. Dusick, M.D. Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, California Carlos Mattozo, M.D. Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, California David L. McArthur, Ph.D., M.P.H. Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, California Pejman Cohan, M.D. Division of Endocrinology, Metabolism and Nutrition, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California John Boscardin, Ph.D. School of Public Health, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, California Christina Wang, M.D. Division of Endocrinology, Metabolism and Nutrition, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California Ronald S. Swerdloff, M.D. Division of Endocrinology, Metabolism and Nutrition, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, California Daniel F. Kelly, M.D. Brain Tumor Center, John Wayne Cancer Institute at Saint John’s Health Center, Santa Monica, California Reprint requests: Daniel F. Kelly, M.D., Brain Tumor Center, 2200 Santa Monica Boulevard, Santa Monica, CA 90404. Email: kellyd@jwci.org Received, January 10, 2008. Accepted, June 2, 2008. ABBREVIATIONS: CSF, cerebrospinal fluid; DI, diabetes insipidus; GH, growth hormone; IGF-1, insulin-like growth factor 1; LH, luteinizing hormone; UCLA, University of California, Los Angeles PITUITARY HORMONAL LOSS AND RECOVERY AFTER TRANSSPHENOIDAL ADENOMA REMOVAL OBJECTIVE: Transsphenoidal adenomectomy carries the possibility of new pituitary failure and recovery. Herein, we present rates and determinants of postoperative hor- monal status. METHODS: All consecutive patients who underwent endonasal transsphenoidal ade- noma removal over an 8-year period were analyzed. Those with previous sellar radio- therapy were excluded. Pre- and postoperative hormonal status (at least 3 mo after surgery) were determined and correlated with clinical parameters using a multivariate statistical model. RESULTS: Of 444 patients (median age 45 years, 75% macroadenoma, 19% with mul- tiple operations), 9 had preoperative panhypopituitarism. Of the remaining 435 patients, new hypopituitarism occurred in 5.5% of patients (anterior loss in 5%; permanent dia- betes insipidus in 2.1%; including 2 patients who had total hypophysectomy). Of 346 patients with preoperative hormonal dysfunction, 170 (49%) had improved function. “Stalk compression” hyperprolactinemia resolved in 73% of 133 patients; recovery of at least 1 other anterior axis (excluding isolated hypogonadism associated with “stalk com- pression” hyperprolactinemia) occurred in 24% of 209 patients. Multivariate analysis showed that new hypopituitarism was most strongly associated with larger tumor diam- eter (P = 0.04). Of 223 patients with an endocrine-inactive adenoma, new hypopitu- itarism was seen in 0, 7.2, and 13.6% of patients with tumor diameters of 20, 20 to 29, and 30 mm, respectively (P = 0.005). Multivariate analysis revealed that resolu- tion of hypopituitarism was related to younger age (39 versus 52 years, P  0.0001), absence of an intraoperative cerebrospinal fluid leak and, in patients with an endocrine- inactive adenoma, absence of systemic hypertension (24% versus 6%, P = 0.009). CONCLUSION: After transsphenoidal adenomectomy, new unplanned hypopituitarism occurs in approximately 5% of patients, whereas improved hormonal function occurs in 50% of patients. The likelihood of new hormonal loss or recovery appears to depend on several factors. New hypopituitarism occurs most commonly in patients with tumors larger than 20 mm in size, whereas hormonal recovery is most likely to occur in younger, nonhypertensive patients and those without an intraoperative cerebrospinal fluid leak. KEY WORDS: Endonasal surgery, Hyperprolactinemia, Hypopituitarism, Pituitary adenoma, Pituitary hor- monal function, Transsphenoidal surgery Neurosurgery 63:709–719, 2008 DOI: 10.1227/01.NEU.0000325725.77132.90 www.neurosurgery-online.com