ORIGINAL ARTICLE

Changes in Thyroid Hormones and Free Triiodothyronine-to-Free Thyroxine Ratio in Euthyroid Patients with Obesity in Terms of Different Glucose Metabolism Statuses
Obezitesi Olan Ötiroid Hastalarda Farklı Glukoz Metabolizması Durumlarında Tiroid Hormonları ve Serbest Triiodotironin/Serbest Tiroksin Oranı
Received Date : 08 Mar 2021
Accepted Date : 02 Jun 2021
Available Online : 21 Jun 2021
Doi: 10.25179/tjem.2021-82919 - Makale Dili: EN
Turk J Endocrinol Metab. 2021;25:279-287
Bu makale, CC BY-NC-SA altında lisanslanmış açık erişim bir makaledir.
ABSTRACT
Objective: The variations of thyroid hormones within normal ranges are observed in different metabolic conditions. Considering available data, levels of thyroid hormones change in obesity and Type 2 diabetes mellitus (DM) in opposite ways. This study aimed to evaluate thyroid hormone levels and free triiodothyronine-to-free thyroxine (fT3/fT4) ratios in different glucose metabolism statuses of euthyroid patients with obesity. Material and Methods: This retrospective study evaluated thyroid hormones and the fT3/fT4 ratio of 209 patients with obesity who were grouped according to their glucose metabolism statuses. Results: One hundred and thirty-one (62.7%) patients had normal glucose tolerance, 41 (19.6%) patients had prediabetes, and 37 (17.7%) patients had DM. Serum fT4 level was found to be higher in patients with DM compared to patients with normal glucose tolerance (p=0.009), although no difference was observed in serum thyroid-stimulating hormone and fT3 levels among groups. FT3/fT4 ratio was determined to be lower in patients with DM than patients with normal glucose tolerance (p=0.012). Hemoglobin A1c was independently and positively associated with fT4 (β=0.345, r2=0.119, p=0.003) and negatively associated with fT3/fT4 ratio (β=-0.371, r2=0.138, p=0.001). Conclusion: Serum fT4 level increased, and fT3/fT4 ratio decreased in patients with Type 2 DM independent of the degree of obesity. The interaction of DM with thyroid hormones in our cohort seemed to overcome obesityrelated changes in thyroid functions.
ÖZET
Amaç: Farklı metabolik durumlarda tiroid hormon düzeylerinde normal referans aralıkta iken bile varyasyonlar görülebilmektedir. Mevcut veriler, obezite ve Tip 2 diabetes mellitustaki (DM) tiroid hormon değişimlerinin farklı yönlerde olduğunu göstermektedir. Bu çalışmada, obezitesi olan ötiroid hastalarda farklı glukoz metabolizması durumlarında tiroid hormon düzeyleri ve serbest tiroksin/serbest triiyodotironin (sT3/sT4) oranlarının değerlendirilmesi amaçlanmıştır. Gereç ve Yöntemler: Bu retrospektif çalışmada, glukoz metabolizması durumlarına göre gruplandırılmış obezitesi olan ötiroid 209 hastanın tiroid hormonları ve sT3/sT4 oranları değerlendirilmiştir. Bulgular: 131 (%62,7) hastada normal glukoz toleransı, 41 (%19,6) hastada prediyabet ve 37 (%17,7) hastada Tip 2 DM mevcuttu. Serum sT4 düzeyleri DM’si olan hastalarda normal glukoz toleransı olanlara kıyasla artmış olarak bulunmuşken (p=0,009), gruplar arasında serum tiroid stimülan hormon ve sT3 düzeylerinde fark izlenmemiştir. ST3/sT4 oranı ise DM’li hastalarda normal glukoz toleransı olanlara kıyasla düşük idi (p=0,012). Hemoglobin A1c düzeyi sT4 ile bağımsız pozitif ilişkili iken (β=0,345, r2=0,119, p=0,003), sT3/sT4 oranıyla bağımsız negatif ilişkiliydi (β=-0,371, r2=0,138, p=0,001). Sonuç: Tip 2 DM’li ötiroid hastalarda obezite derecesinden bağımsız olarak serum sT4 düzeyleri artmış, sT3/sT4 oranı ise azalmış olarak bulunmuştur. Kohortumuzda DM’ye ait tiroid hormon değişimleri obeziteye bağlı tiroid fonksiyonlarındaki değişimlere üstün gelmiş görünmektedir.
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