As part of pre-conceptual planning, the battle rages over my thyroid test results. I’ve had antibodies since diabetes diagnosis, with a most recent level of 68. My TSH is typically between 2.2 and 3.0, well in the normal range of 0.4 to 4.5. The fertility specialist wants a TSH around 1.0 and thinks I should be taking Synthroid, in light of the antibodies. My endocrinologist feels that as long as the TSH and antibodies aren’t going up, and I’m not exhibiting any symptoms, it doesn’t need to be treated. Would taking Synthroid decrease antibody levels and how much would dropping the levels to around 1.0 increase the chances of getting pregnant?

There is some published data on anti-thyroid antibodies and pregnancy outcome, but not very much. With respect to infertility, there was a study (Reprod Biol Endocrinol, Nov 2009) that showed that women with antibodies who received Synthroid, aspirin and steroids had more successful IVF results (conception and pregnancy) than those who did not receive such treatment. However, another recent study (Thyroid, Sep 2010) showed that the presence of antithyroid antibodies did not alter the risk of fetal loss but a higher level of TSH was associated with fetal loss. I am not sure how taking Synthroid would lower the antibody level. Typically, a steroid such as prednisone is used to treat high antibody levels. I would defer to the infertility specialist’s opinion to fine tune your condition to optimize the chances of pregnancy.

OWJ
Additional comments from Dr. Jim Lane:
The direction the fertility specialist wants to go is supported by the Endocrine Society practice recommendation. This is available online. There is some evidence that patients with positive antibodies have an increased risk of miscarriage. Therefore, those with positive antibodies and TSH over 2.0 are recommended to take thyroid hormone replacement. It is a fairly straightforward treatment that could be stopped after pregnancy if you did not want to continue. The issue is whether a thyroid at increased risk, as yours is, can continue to support adequate thyroid hormone production during pregnancy, a time when there is increased stress on the thyroid. If there were difficulty making enough thyroid hormone, the exogenous thyroid you make would protect your baby.

JTL