Endocrine Abstracts

Purpose: Thyroid autoimmune diseases occur more frequently in women than men. A previous study reveals that exogenous testosterone may have a protective effect on thyroid autoimmunity in men with Hashimoto’s thyroiditis. But no study has determined whether sex hormones produce any effect on thyroid antibody titreş in women. The primary study aim was to assess whether exogenous testosterone affects thyroid autoimmunity in trans-men with increasing testosterone levels.

Methods: We designed this study as a single-center prospective study. We included 60 drug-naive trans men, and the control group comprised 26 healthy cisgender women. We measured and compared hormone profiles and metabolic parameters in the two groups initially and after six months under exogenous testosterone. Each participants underwent a preliminary ultrasonography and it was investigated whether there was any abnormality such as a nodule or parenchymal heterogeneity. The thyroid gland was scanned in three dimensions. Depth, width (in transverse plane), and length (in longitudinal plane) of each lobe were measured. Volume of each lobe was calculated using the formula, volume (mL) = π/6 x width x depth x length (15). Total volume was determined as the sum of the volumes of the lobes except for the isthmus.

Results: In patient group, there was no significant difference according to TSH levels (P 0.308) and fT4 levels (P =0.650) before and after treatment. But total testesterone levels and thyroid volume (7.62 ± 2.57 mL and 8.37 ± 2.74 mL; before and after treatment, respectively) were significantly higher after treatment (P<0.001 and P=0.042, respectively). The existence of thyroid nodule didn’t significantly change before and after the treatment (P=0.791)

Conclusion: This study is the first one to have shown that exogenous testosterone may have a effect on thyroid volume in trans men but doesn’t cause an increase in thyroid nodul formation. Testesteron’s effect on thyroid needs to be followed for a longer period to determine accurately.