Low prevalence of growth hormone deficiency in Turkish patients with Hashimoto's thyroiditis

Background: Hashimoto's Thyroiditis (HT) is frequently isolated, but may also be associated with other autoimmune disorders. Autoimmune hypophysitis can result in growth hormone deficiency (GHD). Various prevalences of GHD have been reported in HT in several different ethnic populations. Aim: The aim of this study was assessing the prevalence of GHD in Turkish population with HT. Materials and methods Two hundred twenty-seven (208 females and 19 males, mean age 40.1 ± 10.8 years, range 18-64 years) patients with euthyroid HT were included. Results: All patients were euthyroid with or without T₄ treatment (median TSH 2.2 mIU/L, range 0.2-4.2 mIU/L; median FT₄ 15.6 pmol/L, range 12-22 pmol/L; and median FT₃ 4.5 pmol/L, range 3.0-6.2 pmol/L), and median TPO-Ab was 817 IU/mL (range 63 to >3,000). One hundred and thirty-six of them were using medications including L-thyroxine (59.9%). Insulin-like growth factor-I (IGF-I) levels of 210 patients (92.5%) were normal. Glucagon stimulation testing in 17 subjects revealed GHD (peak <3 mcg/L) in two subjects. We then performed insulin tolerance test (ITT) to both of them as the gold standard confirmatory test. One patient had no GH response to ITT, either. Our data reveal the prevalence of GHD (based on low IGF-I and ITT result) in this particular group of Turkish HT patients as 0.4%. Conclusion: We conclude that the isolated GHD is rarely observed in HT in our population. The prevalence of GHD is 0.4% in this particular group of Turkish HT patients suggesting that routine investigation of GHD is not mandatory.