Thyroid and Assisted Reproduction Technologies: A Brief Clinical Update with Recommendations for Practice.

BACKGROUND AND OBJECTIVE: Infertility is a common disease that in about one third of cases has a female cause and often requires assisted reproduction technologies (ART) to conceive. Also thyroid autoimmunity (TAI), with or without hypothyroidism, is a common disease, particularly in females, and referral for endocrine consultation is not infrequent.

DISCUSSION: In the last 15 years a remarkable amount of studies has been published that investigated the pathophysiology of women suffering from TAI, who undergo ART. Due to insufficient sample size, data about the association between infertility and TAI/subclinical hypothyroidism are conflicting. In relation to pregnancy rate, miscarriage, and live births (primary outcomes) data of the literature do not allow to clearly demonstrating an unfavorable impact attributable to TAI/subclinical hypothyroidism; however, secondary outcomes like ovarian reserve or oocytes quality look like worsened.

CONCLUSION: For sure, the therapeutic regimens used for controlled ovarian hyperstimulation (COH) induce a deterioration of thyroid function in patients suffering from TAI [with or without Levothyroxine (LT4) treatment]. This picture places patients in a condition of increased risk of developing untimely TSH elevation during fertilization; then, it is reasonable that a patient, above all if thyroid antibody positive, would have a TSH value <2.5mIU/L before undergoing COH, and that would be strictly monitored to start or increase LT4 treatment, when necessary.