Doctors update guidelines for detecting, treating hypothyroidism during pregnancy

08/01/2011
In response to findings suggesting a more acute risk of pregnancy complications caused hypothyroidism, a team of researchers associated with the American Thyroid Association (ATA) recently released a list of updated guidelines for the detection and treatment of the thyroid disease in expectant mothers.

The report appeared in the journal Thyroid. It emphasized that the condition can cause a number of serious complications during or after pregnancy, for mother and child alike.

Researchers from the U.S., Argentina, Iran and Italy noted that these can include low birth weight, premature birth or miscarriage, as well as delayed fetal cognitive development and high gestational blood pressure. They added that even sub-clinical hypothyroidism entails a risk of any of these side effects, though the data on this is somewhat scarce.



Approximately 5 percent of Americans suffer from hypothyroidism, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The organization notes that women are much more likely than men to develop the condition, adding that pregnancy puts particular strain on the thyroid gland.



Alex Stagnaro-Green, a member of the ATA panel and lead author of the new guidelines, agreed. He stated that even women with no history of thyroid problems should be aware of the risk of prenatal hypothyroidism, as should their doctors.

"In essence, pregnancy is a stress test for the thyroid, resulting in hypothyroidism in women with limited thyroidal reserve or iodine deficiency," Stagnaro-Green wrote.

The study estimated that the thyroid gland expands by 10 percent in pregnant women with healthy iodine levels, and between 20 and 40 percent among those who have a deficiency of the element.

Furthermore, during pregnancy, the gland requires approximately 50 percent more iodine per day, the group said.

Given that even women with otherwise healthy thyroid function may develop hypothyroidism during gestation, many of the panel's new recommendations focused on increased vigilance, especially among doctors whose patients are either euthyroid or who have a sub-clinical form of the condition.

For example, the team suggested that women be given regular thyroid peroxidase (TPO) antibody tests during pregnancy, since around 20 percent of those with healthy thyroid function during the first trimester nevertheless have TPO antibodies in their blood.

The presence of these compounds carries a risk of hypothyroidism in the second and third trimesters, the ATA panel said. The Mayo Clinic states that having TPO antibodies in one's blood points to the potential for an autoimmune disorder, like Hashimoto's or Graves' diseases.

Researchers added that if a woman is found to be TPO antibody-positive, she should be given oral levothyroxine, a synthetic thyroid hormone.

The panel's full list of recommendations runs to 30 pages. Gregory Brent, president of the ATA, noted the importance of the authors' diverse specializations.

"This broad representation of providers that care for pregnant women will significantly increase the impact of these guidelines and translation of findings from the most recent research to clinical practice," he concluded.