Attitudes of ATA Survey Respondents Toward Screening and Treatment of Hypothyroidism in Pregnancy

Dear Editor:

Whether to screen for thyroid disease in pregnancy is controversial. There is a lack of consensus regarding the merits, or lack thereof, of treating subclinical hypothyroidism or hypothyroxinemia during pregnancy. The 2012 Endocrine Society Guidelines were unable to reach consensus regarding universal screening versus targeted screening based on risk factors (1). The 2011 American Thyroid Association (ATA) guidelines did not recommend universal screening (2). The American Congress of Obstetricians and Gynecologists (ACOG) has stated “there is insufficient data to warrant routine screening of asymptomatic pregnant women for hypothyroidism” (3). The European Thyroid Association notes that there are no well-controlled studies to justify universal screening, but that many authors recommend universal screening “given a targeted approach will miss a large percentage of subclinical hypothyroidism” (4).

We distributed an anonymous multiple-choice survey at the 2012 ATA Annual Meeting (see Supplementary Appendix; Supplementary Data are available online at www.liebertpub.com/thy). Respondents were asked whether to test for thyroid dysfunction or treat hypothyroidism/hypothyroxinemia given different clinical scenarios. Responses were compared across provider demographics using analysis of variance. There were 561 practicing endocrinologists at the meeting. We included 140 responses (24%) from practicing endocrinologists in the analysis. Eleven responses from nonclinicians were discarded. Forty percent of respondents saw 1–10 pregnant women annually, 34% saw 11–40, and 16% saw more than 40. Most respondents (57%) practiced in academic settings. Seventy-five percent had read the 2011 ATA thyroid in pregnancy guidelines, and 68% had read the 2012 Endocrine Society guidelines (published shortly before the meeting). Seventy-four percent advocated for and 18% against universal thyrotropin (TSH) screening in pregnancy; 8% were unsure. Forty percent of the respondents had been in practice for more than 20 years, and they were more likely to screen than those currently in training. Other provider demographics did not predict responses.

Despite the lack of concordance in the guidelines, it is interesting that the majority of respondents favored universal screening. Twenty-five percent of respondents favored treatment of isolated maternal hypothyroxinemia even though the ATA guidelines do not recommend this (2). Interestingly, having read the ATA guidelines did not influence recommendations for or against treating a TSH of >3.5 μIU/mL in a thyroid peroxidase (TPO) antibody negative woman at eight weeks gestation. However, respondents who read the Endocrine Society guidelines were more likely to treat with levothyroxine. In all respondents, thresholds for treatment of mild maternal hypothyroidism were variable. Forty-six percent of respondents would treat TPO antibody negative women with a TSH of 3.5 μIU/mL, while 98% would treat TPO antibody negative women with a TSH of 8.0 μIU/mL. There was no correlation between provider demographics and most survey responses. A summary of the responses is provided in Supplementary Table S1.

In 2009, a survey by Haymart was distributed to more than 500 ACOG members to assess practice patterns. The 11.5% of respondents who had read the 2007 Endocrine Society guidelines were more likely to perform pre-pregnancy screening for thyroid disease risk factors, while 36% of all respondents routinely screened all pregnant patients (5). Similarly, in 2012, Vaidya et al. surveyed members of the European Thyroid Association and noted that 42% of 190 respondents advocated for universal testing, 43% recommended targeted screening of high-risk groups, and 17% did not screen (6). Compared to these previous surveys, a higher proportion of the ATA respondents favored universal screening.

Limitations of our study include the relatively small number of participants. Survey results are reflective of endocrinologists who responded but may not be representative of the wider ATA membership. Although guidelines exist to aid clinicians in their decision making, our survey demonstrates there is a wide variation in practice patterns among thyroidologists with regards to screening for and treatment of low maternal thyroid function during pregnancy. This reflects the conflicting recommendations in existing guidelines. Although there are many observational studies demonstrating adverse effects of mild thyroid maternal hypofunction on obstetric and fetal outcomes, interventional studies demonstrating a treatment benefit are lacking. Additional well-designed prospective studies are required to determine the role and best methods for universal screening versus high-risk case finding. Until more definitive data are available, physicians need to construct individualized plans with their patients when considering screening.