Avoidance of routine thyroid testing on pregnant women would have let 80% of cases go undetected

A recent study completed by researchers from Boston University School of Medicine (BUSM) and Boston Medical Center (BMC) demonstrates that BMC conducts a high rate of thyroid function testing in pregnant women. The retrospective study, which is currently published online in the Journal of Clinical Endocrinology & Metabolism, showed that if BMC had not done routine thyroid testing on pregnant women, approximately 80 percent of cases of mild hypothyroidism (a condition whereby the thyroid does not produce enough thyroid hormone) would not have been detected.

It is known that the thyroid hormone is important for child development in the womb. However, while there are observational studies that show that even slight maternal hypothyroidism is associated with adverse obstetric outcomes and lower child IQ, there is currently no interventional study to show whether treatment for mild hypothyroidism will lead to better outcomes. This lack of information has caused controversy about whether universal thyroid stimulating hormone (TSH) screening is necessary in pregnancy.

Done under the direction of Elizabeth Pearce, MD, MSc, an associate professor of medicine at BUSM, and Donny Chang, MD, PhD, an endocrine fellow at BMC, the team looked at the medical charts of 1,000 pregnant women to determine when and if they received a TSH test during their first prenatal care visit at BMC. The women involved in the study, who were between the ages of 18 and 46, went for their first prenatal visit at either BMC's department of Obstetrics & Gynecology or Family Medicine in 2008. The women's age, race, insurance, gestational age, medical history (thyroid or other autoimmune disorders), obstetric history and thyroid function tests were ascertained.

The results of the study showed that BMC had a higher rate of testing than previously published surveys. While BMC did not conduct universal TSH screenings, they did conduct routine tests for women with no risk factors for hypothyroidism - a group who would normally not be tested under some current guidelines.

"Due to the fact that there are conflicting guidelines, we were surprised to find a high rate of testing here at BMC," said Pearce, from the section of Endocrinology, Diabetes & Nutrition at BMC. "Had BMC not conducted routine testing, there is the potential that many women with mild hypothyroidism would not have been identified."