One of the major challenges in methadone maintenance therapy (MMT) for drug dependence is the physiological side effects on endocrine hormones. Because of the key role of the thyroid gland in the normal functioning of the human body and brain, this study examined the effect of MMT on thyroid function. Thyroid hormones (T3, T4, and thyroid-stimulating hormone (TSH)) were evaluated in normal and user treated with MMT who were referred to the Province Clinical & Pathology Center of Urmia, Iran. The study was conducted for three months using the Case Series method. A total of 270 samples were collected, 215 were from individuals who were not treated, whereas 55 were from men treated with methadone. Average levels of T3 and T4 in non-treated sample of men are 1.34 ± 0.02 ng/mL and 90.96 ± 1.38 ng/mL while the corresponding values for patients treated with methadone are 1.39 ± 0.04 ng/mL for T3 and 94.57 ± 2.72 ng/mL for T4. Mean TSH levels of the non-treated group and the methadone consuming group were 1.75 ± 0.08 μIU/mL and 3.17 ± 0.45 μIU/mL, respectively. These results indicate that although men treated with methadone had higher levels of T3, T4, and TSH than normal individuals, only the difference in TSH level was significant. The importance of this difference among individuals on methadone maintenance programs should be investigated in larger samples over long periods of time. Additionally, the effects of methadone treatment on women should be examined.
Keywords: Methadone maintenance treatment; Radioimmunoassay; Thyroid hormones.