Evaluation of concordancy between IGF-1 and GH after OGTT (oral glucose tolerance test) in monitoring of acromegaly

Abstract

In this study, we aimed to evaluate the concordancy between these two tests in the monitoring of acromegalic patients undergoing medical or surgical treatment and its relation with patients' signs and symptoms. Methods and patients: 49 acromegaly patients who had undergone at least 3 months of surgery and referred to the endocrinology clinic for follow-up performed IGF-1 and GH after OGTT, which were measured in 3 times of 0, 60 and 120 minutes after 75 gr oral glucose. Clinical and metabolic parameters and GHnadir and IGF-1 values were compared between groups. These groups difined as active disease (high GH and IGF-I; n=11), high GH (with normal IGF-I; n=10), high IGF-I (with normal GH; n=13), and controlled disease (GH and IGF-I normal; n=15). Results: 49 patients were studied, the mean age of patients was 47.5 (25-74) years, 18 males (36.7%) and 31 females (63.3%). 25 patients (51%) had normal IGF-1 based on their age and sex and 24 patients (49%) had higher IGF-1 above the normal range. 28 patients (57.1%) had GHn <1 µg / L and 21 patients (42.66%) had GHn≥ 1 µg / L. based on IGF-1 and GHn results, 26 patients (53%) had concordance results, and 23 patients (47%) had diccordance results in two opposite directions. The most patern of discordancy was high IGF-1 and normal GHnadir which was seen in 13 patients (26. 5%).discorncy in patern of high GH and normal IGF-1 was seen in 10 persons (22.4%). corrected IGF-1 and GHn compared with each other in 4 groups of pateints. There was a significant difference between the corrected IGF-1 values of the high IGF-1 group and active disease (1.4±0.42 vs 2.32±0.85; p=0.001). It means when discordancy observed in high IGF-1 and normal GHn patern, IGF-1 is only mildly elevated in compression with active disease. While there was no significant difference between GHn in high GHn group and active disease group (3.5±2.7µg/L vs 2.84±1.8; p=0.8) respectively. sign and symptoms and medication and MRI results and the presence of diabetes and hypertension were not significantly different in the 4 groups of patients. clinical symptoms were not in relation with IGF-1 and GH results. Discussion & Conclusion: There is a significant inconsistency between the results of IGF-1 and GHn in monitoring of acromegalic patients, in which case the clinical symptoms do not help to decidion making of management. Also, when GH-0 is <1 µg/L, the use of GHn does not help more in f/u. There is a need for more frequent monitoring for early diagnosis of recurrence of disease. also use of other biomarkers was also suggested for better decision making.