Although oral isotretinoin has been widely used as a basic treatment of acne in adolescents, several studies have noted some alterations in thyroid functions during oral isotretinoin therapy. Therefore, the present study aims at evaluating the possible changes in thyroid-stimulating hormone (TSH), free thyroxin (fT4) and free triiodothyronine (fT3) levels during isotretinoin treatment and analyzing the possible factors which may contribute to such changes. In the present study, 47 patients received (0.5 mg/kg oral isotretinoin) for treatment of severe acne. TSH, fT4 and fT3 were measured at baseline, after 3 and 6 months. ANOVA tests were used for statistical analyses. The levels of fT4 and fT3 decreased significantly during isotretinoin treatment (from 0.85 ± 0.04 and 3.1 ± 0.26 at baseline to 0.81 ± 0.023 and 2.76 ± 0.2 after 6 months, respectively). The decrease was accompanied by significant elevation of TSH (0.66 ± 0.05 at baseline to 0.695 ± 0.05 after 6 months). The duration of therapy (but not the dose) has significantly affected all the hormonal changes. Previous incomplete or intermittent isotretinoin treatment had significantly influenced the changes in fT4 only, while gender affected the changes of TSH. Isotretinoin treatment can decrease fT4, fT3 and increase TSH. The pattern of these changes was affected by gender and previous isotretinoin therapy. Different doses of isotretinoin did not affect the hormonal changes, but the duration has been the major influencing factor.
Keywords: T3 and TSH; acne; isotretinoin; thyroid.
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