Thyroid hormone treatment in euthyroid women with unexplained sterility under intracytoplasmic sperm injection: a pilot study

Abstract

INTRODUCTION: Thyroid hormones have several implications in the human body. One of thyroid actions has been demonstrated to be in the ovaries. Oocytes respond to T3 as T3, T4, deiodinases and thyroid receptors have been discovered to exist in human oocytes. Thyroid influence in oocytes is not well-known but it seems that thyroid hormone is needed for a good oocyte development. An inhibitory thyroid receptor, TRα2, is increased in granulosa cells of sterile women compared to fertile women. As sterility is known to be age-related, it could be a possible cause of sterility as TRα2 has been proven to increase with age. OBJECTIVE: To test whether the administration of levothyroxine in euthyroid women between 30 and 40 years old with unexplained sterility increases their fertilization rate in ICSI compared to placebo. DESIGN: Longitudinal, prospective, randomized, double-blinded, controlled clinical trial (pilot study). POPULATION: Euthyroid women between 30 and 40 years old with unexplained sterility. SAMPLE SELECTION: Consecutive non-probabilistic. SAMPLE SIZE: 40 patients equally and randomly distributed into 2 groups: the intervention group (treatment with levothyroxine) and the control group (placebo). METHODS: Patients included in the study will take a 3 months treatment with either levothyroxine or placebo. After that, they will undergo to an ICSI cycle. They will then start a COS antagonist protocol using a GnRH agonist as ovulation triggering. The resulting oocytes will be aspired and inseminated by ICSI once isolated and denudated. The injected oocytes will be conserved in an Embryoscope and observed after 16-20 hours to check which ones have been successfully fecundated