l-selenomethionine supplementation in children and adolescents with autoimmune thyroiditis: A randomized double-blind placebo-controlled clinical trial.

WHAT IS KNOWN AND OBJECTIVE: Although a beneficial effect of selenium (Se) administration has been proposed in adults with autoimmune thyroiditis (AT), there is a paucity of similar data in children and adolescents. The purpose of the study was to investigate whether administration of a high dose of organic Se (200 μg daily as l-selenomethionine) has an effect on antithyroid antibody titres in children and adolescents with AT.

METHODS: Seventy-one (71) children and adolescents, with a mean age of 11.3 ± 0.3 years (range 4.5-17.8), diagnosed with AT (antibodies against thyroid peroxidase [anti-TPO] and/or thyroglobulin [anti-Tg] ≥60 IU/mL, euthyroidism or treated hypothyroidism and goitre in thyroid gland ultrasonography) were randomized to receive 200 μg l-selenomethionine or placebo daily for 6 months. Blood samples were drawn for measurement of serum fT4, TSH, anti-TPO and anti-Tg levels, and thyroid gland ultrasonography was performed at the entry to the study and after 6 months of treatment.

RESULTS AND DISCUSSION: At the end of the study, a statistically significantly higher reduction in anti-Tg levels was observed in the Se group compared to the placebo group (Δ: -70.9 ± 22.1 vs -6.7 ± 60.6 IU/mL, P = 0.021). Although anti-TPO levels were also decreased in the Se group, this change was not statistically different from that of the control group (Δ: -116.2 ± 68.4 vs +262.8 ± 255.5 IU/mL, P = 0.219). No significant difference in thyroid gland volume was observed between the two study groups (P > 0.05).

WHAT IS NEW AND CONCLUSION: In this original study, organic Se supplementation appears to reduce anti-Tg levels in children and adolescents with AT.