July - September 2008, Volume 4, Issue 3

Niculescu DA, Purice M, Lichiardopol R, Ciubotaru V, Coculescu M

Short-term impact on glycemic control of partial removal of the tumor mass by transsphenoidal surgery for naive GH-secreting pituitary macroadenomas

Acta Endo (Buc) 2008, 4 (3): 287-295
doi: 10.4183/aeb.2008.287

Glycemic control can be impaired in active acromegaly and insulin sensitivity (IS) decreases with rising growth hormone (GH) levels.\r\nAim. To assess the short-term impact of transsphenoidal surgery for acromegaly on glycemic control. Methods. 11 patients with native active acromegaly due to pituitary macroadenoma were assessed before and after (2-3 months) transsphenoidal hypophysectomy. Serum glucose, GH and insulin levels were measured by immunoradiometric assay at 0, 30, 60 and 120 minutes during a 75 g OGTT before and after surgery. IGF-1 levels were measured by ELISA. Basal hepatic IS was assessed using HOMA-S% and QUICKI indexes and stimulated IS using OGTTISI. Basal and stimulated insulin secretion was assessed using HOMA-B% index and IGI respectively. Results. All patients had their acromegaly improved (mean?SD pretreatment nadir GH 34?24.7 ng/mL vs. 4.6?3.5 ng/mL postsurgery; p<0.001) but only one was cured (nadir GH<1 ng/mL, normal IGF- 1 level). Mean fasting serum glucose was lowered by 7.9 mg/dL (95% CI 1.3-14.4, p=0.03) and fasting serum insulin by 9.6 mU/mL (95% CI 1.0-18.1, p=0.02). IS increased after surgery as shown by HOMA-S% index which rose 0.25?0.18 to 0.5?0.36 (p<0.01), QUICKI which rose form 0.31?0.03 to 0.33?0.03 (p=0.001) and OGTTISI index which rose from 2.5?1.6 to 5.1 ? 3.5 (p=0.002). Insulin secretion was unchanged as shown by HOMA-B% index (313?229 presurgery vs. 227?139 postsurgery, p=NS) and IGI index (0.96 ? 0.86 presurgery vs. 0.55 ? 0.49, p=NS). Conclusions. Partial removal of the pituitary adenoma by transsphenoidal surgery in patients with acromegaly induces a significant increase in insulin sensitivity and an improvement in glycemic control at 3 months after surgery. This suggests that transsphenoidal surgery should be indicated even if complete removal of the pituitary adenoma is not achieved.

Keywords: active naive acromegaly, insulin resistance, transsphenoidal pituitary surgery, insulin secretion

Correspondence: Mihail Coculescu, M.D., Department of Endocrinology, &#8220;Carol Davila&#8221; University of Medicine and Pharmacy , 34-36 Aviatorilor Blvd, 011863 Bucharest, Romania, e-mail: m.coculescu@uni-davila.ro