Rates of thyroid testing high in pregnant women

Chang DL. J Clin Endocrinol Metab. 2011;doi:10.1210/jc.2011-0360.

Results of a recent retrospective study revealed that health care professionals at Boston Medical Center conduct a high rate of thyroid function tests in pregnant women.

If the routine thyroid testing was not conducted in pregnant women there, about 80% of cases of mild hypothyroidism may have been missed, researchers found.

Guidelines from various medical associations differ as to whether thyroid testing during pregnancy is appropriate, according to the article published in the Journal of Clinical Endocrinology & Metabolism. For example, some guidelines support screening only high-risk women, whereas others recommend case-finding or routine testing before becoming pregnant.

To determine rates of thyroid screening and thyroid dysfunction, Elizabeth N. Pearce, MD, associate professor of medicine at Boston University School of Medicine, and colleagues retrospectively examined 1,000 pregnant women aged 18 to 46 years. All were seen in the family medicine or obstetrics and gynecology clinics at the institution.

Elizabeth N. Pearce, MD

Nine hundred eighty-three women met inclusion criteria (median maternal age, 28 years; median gestational age, 9.4 weeks). At 84% and 86%, respectively, rates of thyroid screening were similar between the 918 women seen in obstetrics and gynecology clinics and the 65 women seen in family medicine clinics. Of 39 women with a previous history of thyroid disease, 19 took thyroid medications; four had type 1 diabetes; and nine had other autoimmune disorders.

The researchers found 832 patients who had serum thyroid-stimulating hormone taken at a median gestational age of 9.7 weeks; 65.5% had their TSH obtained during the first trimester, 22.1% during the second trimester and 12.4% during the third trimester. According to trimester-specific reference ranges, 56 women had elevated TSH. Of these women, nine had a previous history of thyroid disease, two had type 1 diabetes and one had dyschromia. Only these women would have qualified for thyroid testing according to Endocrine Society guidelines for case-finding, leading to a possible missed diagnosis among 80.4% of women with elevated TSH, the researchers said.

“Due to the fact that there are conflicting guidelines, we were surprised to find a high rate of testing here at Boston Medical Center,” Pearce said in a press release. “Had Boston Medical Center not conducted routine testing, there is the potential that many women with mild hypothyroidism would not have been identified.”

Disclosure: The researchers report no relevant financial disclosures.

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