Changes in thyroid volume and thyroid function in acromegaly after surgery in Chinese population

Abstract Background : An increased prevalence of thyroid lesions was observed in acromegaly patients. However, the change of thyroid after remission of acromegaly was not clear in Chinese populations. The aims were to assess the thyroid structure and function changes before and after transsphenoidal pituitary adenoma resection in patients with acromegaly and to investigate the correlation between GH, IGF-1, disease duration and thyroid structure and function. Methods : We retrospectively studied 78 patients with acromegaly who underwent surgery between 2015 January and 2018 January at Peking Union Medical College Hospital. The pituitary hormone: random growth hormone (GH), nadir GH and insulin-like growth factor-1 (IGF-1); the thyroid hormone: thyroid stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3), free thyroxine (FT4) and free triiodothyronine (FT3); four parameters of thyroid metabolism: thyroid’s secretory capacity (SPINA-GT), the sum activity of peripheral deiodinases (SPINA-GD), standard TSH index (sTSHI) and thyrotrophic thyroid hormone sensitivity index (TTSI); and thyroid ultrasound were assessed at baseline and 1 year after surgery. Results : Thyroid volume was significantly positively related random GH, nadir GH, and disease duration. TSH, sTSHI and TTSI was negatively related with pituitary hormone while IGF-1 showed a significant positive association with FT4 and SPINA-GT. After transsphenoidal resection of pituitary adenoma and over 1 year follow-up, the thyroid volume decreased significantly (p=0.000). T3 (p=0.049) and FT3 (p=0.022) also decreased significantly though within normal ranges. However, no significant changes were found in nodule maximum diameter and sTSHI. Thyroid volume change was positively correlated with GH change and nadir GH change. T3 change as well as SPINA-GD change was positively associated with IGF-1 change. Though no significant difference were observed between controlled patients and those who did not achieved “control” level, control patients had a larger decline in thyroid volume along with a smaller decrease in TSH. Conclusion: Enlarged thyroid volume, prevalent thyroid nodules, suppressive pituitary thyrotrophic function and elevated peripheral thyroid hormones are characteristic in acromegaly. A decrease in GH could have favorable effect on thyroid status on thyroid volume and thyroid hormones, while established thyroid nodules and impaired pituitary thyrotrophic function seemed to change little after surgery.