High Anti-thyroid Antibodies:
Associated with Adverse Pregnancy Outcomes
Even among Euthyroid Women

Dr. John C. Lowe
Editor-in-Chief
March 8, 2010

Women often contact us to express a common concern. Their doctors have told them that their high anti-thyroid antibody levels are of no importance to their health. The women also tell us how their doctors justify this belief to them: “You’re ‘euthyroid,’ the doctors explain. “That means your TSH is ‘in range.’ And when your TSH is in range, your thyroid function is just fine. So don’t worry about the antibodies.”

But two groups of women do remain concerned; some of them are even fearful. Most of the women in both know that high anti-thyroid antibodies mean they have autoimmune thyroid disease. They also have read enough to know that an in-range TSH level is no assurance whatever that a person has enough thyroid hormone regulation to be healthy.

One group of the women is concerned about their high anti-thyroid antibody levels because they aren’t able to get pregnant. They fear that their autoimmune thyroiditis is responsible for their infertility.

The second group of women remain concerned about their high anti-thyroid antibodies because they’ve had troubled or failed pregnancies. They, too, suspect that autoimmune thyroid disease is responsible.

I’ll be forthright and say here that both groups of women do indeed have good reason for concern over their anti-thyroid antibody levels. Below I support this proposition by briefly reviewing some of the relevant evidence. That evidence, to give a more specific proposition, shows this—even in women with in-range TSH and thyroid hormone levels, high anti-thyroid antibodies are associated with both infertility and complicated and failed pregnancies.

Ovarian stimulation and in vitro fertilization. In 2009, Italian researchers wrote, “Anti-thyroid antibodies, even if not associated with thyroid dysfunction, are suspected to cause a poorer outcome of in vitro fertilization.” (Italics mine.) They analyzed patients’ records for the prevalence of autoimmune thyroiditis among infertile women who had reference range TSH and thyroid hormone levels. The prevalence of high antibodies in euthyroid women was 10.5%.

Some of the women with autoimmune thyroiditis didn’t undergo thyroid hormone therapy. Compared to control women, these untreated women didn’t respond as well to ovarian stimulation and in vitro fertilization.

The researchers noted that women who used T4 responded better to ovarian stimulation. However, they responded no better to in vitro fertilization than did women with autoimmune thyroiditis who didn’t undergo thyroid hormone therapy. But women who were treated with combined thyroid hormone, aspirin, and prednisolone responded as well to in vitro fertilization. In fact, they responded as well as women who didn’t have autoimmune thyroiditis.

The findings from this Italian study support the 2008 findings of Spanish researchers.[6] These researchers found that women with implantation failure had a higher incidence of both thyroid peroxidase (TPO) and anti-thyroglobulin antibodies—despite the patients’ TSH and free T4 levels being in-range.

The Spanish researchers also found that both types of anti-thyroid antibodies were higher in women with “unexplained infertility” than in women with recurrent spontaneous abortion. (This is an important finding in that women with recurrent spontaneous abortion also have a high incidence of anti-thyroid antibodies.[3,4,5]) And once more, the women with unexplained infertility had in-range TSH and free T4 levels. The Spanish researchers wrote that thyroid autoimmunity in euthyroid women is “strongly” related to both unexplained infertility and implantation failure.[6]

Euthyroid autoimmune thyroiditis. In a review 2009 paper,[1] Dr. R. Gärtner pointed out that women who are euthyroid but have high thyroid peroxidase antibodies more often have miscarriages, preterm deliveries, and postpartum thyroiditis. (He believes that if these euthyroid women begin taking T4 early in their pregnancies, they’re less likely to have pregnancy complications.)

Indeed, whether the women are euthyroid or hypothyroid, if they have high anti-thyroid antibodies, they are more susceptible to reproductive problems. In 2000, researchers in Greece found that compared to control women, women with recurrent spontaneous miscarriage had a higher incidence of high anti-thyroid antibodies.[3] In 2004, Israeli researchers found a statistically significant association between thyroid peroxidase antibodies recurrent miscarriages[4] And in 2008, Iranian researchers reported that compared to controls, women with recurrent spontaneous abortions had a significantly higher incidence of both thyroid peroxidase and anti-thyroglobulin antibodies. They concluded, “. . . thyroid autoimmunity was independently associated with a higher risk of recurrent abortion.”[5]

Subclinical hypothyroidism. Dr. Gärtner noted[1] that if a pregnant mother isn’t euthyroid but has subclinical hypothyroidism, this may impair normal development of the fetus. The mother, he wrote, should undergo thyroid hormone therapy even when her TSH is within the upper end of the reference range. And again, for emphasis perhaps, he wrote, “Special care is necessary in women with elevated TPO antibodies, because these [women] more often develop postpartum thyroiditis.”

Conclusion. The research literature contains sufficient evidence that high anti-thyroid antibodies are associated with infertility and troubled pregnancies. Because of this, in my opinion, if you’re a euthyroid woman with high anti-thyroid antibodies, and you’re concerned that these may be associated with your infertility or problematic pregnancies, your concern is warranted.

Let your concern motivate you. If you want to continue working with your current clinician who has been mistaken about the issue, then share the research I’ve cited in this article with him or her. Hopefully he or she will cooperate with you so as to relieve your concerns. If not, however, let your concern motivate you to find another clinician who will cooperate with you. In either case, work with the clinician you choose to relieve any health problems you have related to your autoimmune thyroiditis—and especially, of course, any reproductive problems you have.

References

1. Gärtner, R.: Thyroid disorders during pregnancy. Dtsch. Med. Wochenschr., 134(3):83-86, 2009. (Medizinische Klinik Innenstadt der Universität München. roland.gaertner@med.uni-muenchen.de2.)

2. Revelli, A., Casano, S., Piane, L.D., et al.: A retrospective study on IVF outcome in euthyroid patients with anti-thyroid antibodies: effects of levothyroxine, acetyl-salicylic acid and prednisolone adjuvant treatments. Reprod. Biol. Endocrinol., 7:137, 2009. (Reproductive Medicine and IVF Unit, Department of Obstetrical and Gynecological Sciences, University of Torino, OIRM-S, Anna Hospital, Torino, Italy. fertisave@yahoo.com.)

3. Dendrinos, S., Papasteriades, C., Tarassi, K., et al.: Thyroid autoimmunity in patients with recurrent spontaneous miscarriages. Gynecol. Endocrinol., 14(4):270-274, 2000. (Second Department of Obstetrics and Gynecology, University of Athens, Greece.)

4. Marai, I., Carp, H., Shai, S., et al.: Autoantibody panel screening in recurrent miscarriages. Am. J. Reprod. Immunol., 51(3):235-240, 2004. (Department of Medicine 'B', Center for Autoimmune Diseases, Sackler Faculty of Medicine, Tel-Aviv University, Tel Hashomer, Israel.)

5. Iravani, A.T., Saeedi, M.M., Pakravesh, J., et al.: Thyroid autoimmunity and recurrent spontaneous abortion in Iran: a case-control study. Endocr. Pract., 14(4):458-464, 2008. (School of Medicine, Medical Sciences/University of Tehran, Tehran, Iran. Iravani_amir@yahoo.com.)

6. Bellver, J., Soares, S.R., Alvarez, C., et al.: The role of thrombophilia and thyroid autoimmunity in unexplained infertility, implantation failure and recurrent spontaneous abortion. Hum. Reprod., 23(2):278-284, 2008. (Instituto Valenciano de Infertilidad (IVI), University of Valencia, Plaza de la Policía Local, 3, 46015 Valencia, Spain. jbellver@ivi.es.)

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