No differences in metabolic outcomes between nadir GH 0.4 and 1.0 ng/mL during OGTT in surgically cured acromegalic patients (observational study)

Abstract

Metabolic impairment is the common cause for mortality in acromegalic patients. In this study, long-term improvements of metabolic parameters were evaluated according to 2 different remission criteria.This was an observational cohort study before and up to 1 year after transsphenoidal adenomectomy (TSA). Participants were 187 patients with acromegaly. At 6 months after TSA, remitted patients with age- and sex-matched normalized IGF-1 were divided into 2 groups: remission 1 (R1), nadir growth hormone (GH) below 0.4 ng/mL; and remission 2 (R2), nadir GH between 0.4 and 1.0 ng/mL in oral glucose tolerance test (OGTT). Metabolic parameters during serial OGTTs were evaluated for 12 months. Remission was achieved in 157 (R1-136; R2-21) patients. Immediate postoperative metabolic parameters including body weight, body mass index, glucose, insulin, and free fatty acid in OGTT were all significantly improved in R1 and R2. HOMA-%β and HOMA-IR scores also improved in both R1 and R2. These improvements persisted for duration (12 months) of this study. However, no difference was present in metabolic parameters between R1 and R2. Although the patients with preoperative adrenal insufficiency presented significantly increased HOMA scores before TSA, there was no difference between classifications of deficient pituitary axes and changes of metabolic parameters after TSA. Remitted patients exhibited rapid restoration of metabolic parameters immediate postoperative period. Long-term improvements in metabolic parameters were not different between the 2 different nadir GH cut-offs, 0.4 and 1.0 ng/mL.

Figure 1

Changes free fatty acids during 75 g glucose tolerance test. During 75 g oral glucose tolerance tests, free fatty acids were measured serially before, at a week, at 6 months, and at 12 months after transsphenodial adenomectomy. At each period, there was no difference in fasting (A) and glucose-suppressed (B) free fatty acids between different cut-off GH values. White box: patients in remission with age-matched and sex-matched normal IGF-1 levels and nadir GH levels below 0.4 ng/mL (R1). Gray box: patients with age-matched and sex-matched normal IGF-1 levels and nadir GH levels ranging from 0.4 to 1.0 ng/mL (R2). Boxes indicate interquartile ranges. Horizontal bars indicate median levels.

Figure 2

Changes in HOMA scores in patients with acromegaly after transsphenoidal adenomectomy. HOMA-%β (A) and HOMA-IR (B) scores were measured in patients of Group 1 and Group 2 during the 75 g oral glucose tolerance test at 6 months after transsphenoidal adenomectomy. P values were calculated with the Wilcoxon signed rank test after comparing the values before and after transsphenoidal adenomectomy. White box: patients in remission with age-matched and sex-matched normal IGF-1 levels and nadir GH levels below 0.4 ng/mL (R1). Gray box: patients with age-matched and sex-matched normal IGF-1 levels and nadir GH levels ranging from 0.4 to 1.0 ng/mL (R2). Boxes indicate interquartile ranges. Horizontal bars indicate median levels.

Figure 3

Categorization of glucose homeostasis during the 75 g glucose tolerance test. According to the result of the 75 g oral glucose tolerance test, each patient was classified into one of the following 3 categories: diabetes mellitus (DM), impaired fasting glucose (IFG)/impaired glucose tolerance (IGT), and normal. No significant differences were observed between patients of R1 (A) and R2 (B).

Figure 4

Effect of each pituitary hormone on HOMA scores before and after transsphenoidal adenomectomy. HOMA-%β (A, C) and HOMA-IR (B, D) scores were measured before (A, B) and at 6 months after transsphenoidal adenomectomy (C, D) in patients in remission from acromegaly. P values were calculated with the Mann–Whitney U test. White box: intact secretory function of each hormone. Gray box: deficient secretory function of each hormone. Boxes indicate interquartile ranges. Horizontal bars indicate median levels.