Abstract
BACKGROUND: Addiction increases the risk of different lifelong disorders. However, there are limited studies evaluating the effects of opioid use disorder (OUD) on thyroid function. The present study aimed to compare the thyroid function of individuals with and without OUD. METHODS: This cross-sectional study was conducted on 700 eligible participants of the Persian Cohort of Fasa, Iran. Pregnant women and participants with false or missing data were excluded from the study. Remained participants were divided into case and control groups based on the recorded history of OUD. Frozen plasma samples of the cohort bank were used to determine the levels of T3, T4, and thyroid-stimulating hormone (TSH). The thyroid function was compared between the two groups using the Mann-Whitney test (P < 0.05). RESULTS: The mean age of the final studied population (n = 648) was 54.0 ± 9.8 years, including 336 men (49.1%) and 197 participants with OUD (28.8%). The median levels of TSH, T4, and T3 were 2.91 ± 4.61, 9.26 ± 3.65, and 1.22 ± 0.49, respectively. The case group had significantly higher TSH (3.72 ± 6.2 vs. 2.58 ± 3.75, P < 0.001) and lower T4 (8 ± 3.6 vs. 9.8 ± 3.5, P < 0.001). Also, T3 was slightly lower in the case group (1.1 ± 0.5 vs. 1.3 ± 0.5; P = 0.369), although this association was only significant in female opium users (P < 0.001). CONCLUSIONS: The present findings revealed that OUD caused a reduction in T4 while increasing TSH. Therefore, OUD may lead to the development of primary hypothyroidism, which needs to be investigated in future studies.