Reproductive-Age Women May Benefit From TPO Screening
Yael Waknine
June 18, 2004 — Pregnant women may benefit from prenatal screening for anti-thyroperoxidase (TPO) antibodies associated with thyroid stimulating hormone (TSH) elevation and hypothyroidism, according to a study presented at the 86th annual meeting of The Endocrine Society in New Orleans, Louisiana.
Study results showed that mild TSH elevation has a prevalence of 3.1% in women of reproductive age and affects an estimated 40,000 pregnant and 1,600,000 nonpregnant women in the U.S.
“Prior work has demonstrated that [children of] women who unwittingly had abnormal thyroid [levels] during the time of pregnancy have had adverse neuropsychological developments,” lead author Ruth Belin, MD, from the Division of Endocrinology at John Hopkins University School of Medicine in Baltimore, Maryland, told Medscape. “Depending on the degree of thyroid abnormality, neuropsychologic impairment could involve a very subtle decrease in IQ scores.... Some studies have also looked at visual changes and memory changes in children who are hypothyroid or who have been exposed to hypothyroidism.”
According to Dr. Belin, prior studies have evaluated the prevalence of thyroid abnormalities in women during the first trimester of pregnancy. “We felt that it was important to also screen women who could potentially become pregnant, because by the time they get to their obstetrician for screening they may be six to eight weeks into the time of their pregnancy,” Dr. Belin said. “If there are abnormalities, we want to know beforehand.”
To evaluate the magnitude of thyroid dysfunction in women of reproductive age, investigators used TSH test data of 5,616 women aged 17 to 45 years from the Third National Health and Nutrition Examination Survey (NHANES III). Results showed that 1.3% of pregnant women (95% confidence interval [CI], 0% - 2.2%) and 3.1% of all women (95% CI, 2.3% - 3.9%) who could potentially become pregnant had TSH elevations higher than 4.5 mU/L.
The presence of TPO antibodies was strongly associated with TSH elevation in both pregnant (odds ratio [OR], 100; 95% CI, 5 - 3000) and nonpregnant women (OR, 20; 95% CI, 10 - 40).
“The study actually showed that an antibody test might be useful to identify women that are particularly at risk — women with positive antibodies were even more likely to have thyroid/TSH abnormalities,” Dr. Belin noted, adding that antibody test results are more definitive than those for TSH testing in diagnosing hypothyroidism. “Theoretically, TPO antibody testing could be a first approach to screening,” she concluded.
This research was funded by the Flight Attendant Medical Research Institute and by the National Institute of Diabetes and Digestive and Kidney Diseases.
ENDO 2004: Abstract P2-473. Presented June 17, 2004.
Reviewed by Gary D. Vogin, MD
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Article: Reproductive-Age Women May Benefit From TPO Screening 
