Selenium supplementation in the management of thyroid autoimmunity during pregnancy: results of the “SERENA study”, a randomized, double-blind, placebo-controlled trial

Purpose: Selenium is frequently in nutraceuticals for pregnancy, given its role on fertility and thyroid metabolism. However, most evidence rise from non-controlled studies. We aimed to evaluate the protective effect of selenium against thyroid autoimmunity during and after pregnancy. Methods: A multicenter, randomized, double-blind, placebo-controlled trial was performed and promoted by the Young Italian Endocrinologists Group (EnGioI)—Italian Society of Endocrinology. Forty-five women with thyroiditis in pregnancy were enrolled and randomly assigned to L-selenomethionine (L-Se-Met) 83 mcg/day or placebo (PLB) and evaluated at 10 ± 2 (T1), 36 ± 2 weeks of gestation (T2) and 6 months after delivery (postpartum, PP). Results: We measured a significant reduction of autoantibodies after pregnancy in L-Se-Met group [at PP: TgAb 19.86 (11.59–52.60), p < 0.01; TPOAb 255.00 (79.00–292.00), p < 0.01], and an antibodies titer’s rebound in PLB group (TgAb 151.03 ± 182.9, p < 0.01; TPOAb 441.28 ± 512.18, p < 0.01). A significant increase in selenemia was measured in L-Se-Met group at T2 (91.33 ± 25.49; p < 0.01) and PP (93.55 ± 23.53; p = 0.02). Two miscarriage occurred in PLB. No differences were found in thyroid volume, echogenicity, quality of life, maternal/fetal complications. Conclusions: SERENA study demonstrated a beneficial effect of L-Se-Met supplementation on autoantibody titer during pregnancy and on postpartum thyroiditis recurrence.