Postpartum thyroiditis (PPT) is an autoimmune disorder characterized by lymphocytic infiltration of the thyroid gland and by the occurrence, in the postpartum period, of transient hyperthyroidism and/or transient hypothyroidism. Most women return to the euthyroid state by 1 year postpartum. The prevalence pf PPT is about 7.58.5%, then it represents a quite common disease, even if it may be asymptomatic in most cases. Women positive for thyroid peroxidase antibodies (TPOAb(+)) are prone to develop hypothyroidism during pregnancy and thyroid dysfunction after delivery. About 50% of TPOAb(+) pregnant women have PPT, and among these, more than 40% are affected by permanent hypothyroidism that develops in subsequent years. Factors predictive of thyroid dysfunction include a hypothyroid form of postpartum thyroid disease, high TSH values, and high TPOAb titers.
The clinical presentation of thyroid dysfunction occurring after delivery, may be characterized by hypothyroidism, hyperthyroidism, or hyperthyroidism followed by hypothyroidism (biphasic form).
Two studies, in 1990 and 2000, have investigated the chance of preventing PPT. Results showed that the administration of levothyroxine or iodine during or after pregnancy is not able to reduce the incidence of thyroid dysfunction after delivery.
Selenium (Se) exerts multiple actions on endocrine systems by modifying the expression of at least 30 selenoproteins, many of which have clearly defined functions. Well-characterized selenoenzyme families include the glutathione peroxidases (GPx), thioredoxin reductases, and iodothyronine deiodinases. These selenoenzymes influence cell function by acting as antioxidants, modifying redox status and thyroid hormone metabolism. Se supplementation may decrease inflammatory activity in patients with autoimmune thyroiditis, especially in those with high activity, reduces TPOAb titers, and ameliorates the thyroid echogenicity pattern.
To test the hypothesis that Se supplementation may be beneficial on thyroid autoimmunity and post-partum thyroid dysfunction (PPTD), 169 euthyroid, TPOAb(+) pregnant women were randomly divided into two groups: group S1 (85 women), designed to receive selenomethionine 200 μg/d after 12 week gestation; and group S0 (84 women), designed to receive placebo. In addition, 85 TPOAb(−) age-matched women were recruited as the control group (group C).
Results showed that Se supplementation reduced the number of thyroid dysfunction during the postpartum period (28.6 vs 48.6%) and the number of permanent hypothyroid patients at 12 months after delivery (11.7 vs 20.3%); furthermore, lower TPOAb titers were observed in the Se-treated patients during and after gestation, and the same patients 12 months after delivery displayed a significantly better ultrasound pattern.
This study shown for the first time that Se supplementation during and after pregnancy inhibits the progression of autoimmune chronic thyroiditis. Se administration in the dosage of 200 μg/d during pregnancy and the postpartum period exerted an anti-inflammatory action, reduced TPOAb titers, and ameliorated the ultrasound echogenicity pattern with respect to controls. Se supplementation improved the course of the destructive thyroid gland process that occurs after parturition, reducing the incidence of PPTD and hypothyroidism.
25 - 29 Apr 2009
European Society of Endocrinology