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Endocrine Care: Bijay Vaidya, Sony Anthony, Mary Bilous, Beverley Shields, John Drury, Stewart Hutchison, and Rudy Bilous Detection of Thyroid Dysfunction in Early Pregnancy: Universal Screening or Targeted High-Risk Case Finding? J Clin Endocrinol Metab 2007; 92: 203-207 [Abstract] [Full text] [PDF]

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Is Universal Screening for detection of thyroid dysfunction in Early Pregnancy justified ?

Ling Choo Lim, Su Chi LIM, Kian Peng GOH, Vivien CC LIM, Rajmohan LEKSHMINARAYANAN, Tavintharan SUBRAMANIAM, Chee Fang SUM   (13 March 2007)

Is Universal Screening for detection of thyroid dysfunction in Early Pregnancy justified ? 13 March 2007
Ling Choo Lim, Physician Alexandra Hospital, Singapore, Su Chi LIM, Kian Peng GOH, Vivien CC LIM, Rajmohan LEKSHMINARAYANAN, Tavintharan SUBRAMANIAM, Chee Fang SUM Send letter to journal: Re: Is Universal Screening for detection of thyroid dysfunction in Early Pregnancy justified ? Ling_Choo_Lim{at}alexhosp.com.sg Ling Choo Lim, et al.	We read with interest the report by Vaidya et al. (1). The authors’ effort in conducting such an extensive survey of thyroid status among 1560 pregnant subjects is highly commendable. Based on their findings, the authors and the accompanying editorial (2) questioned the recent consensus guidelines from an expert panel sponsored by the American Thyroid Association, the American Association of Clinical Endocrinologists, and The Endocrine Society. This consensus guideline did not advocate universal screening of thyroid function during pregnancy, but recommended aggressive case finding in high-risk pregnant women (3). We suggest that the data of this report, when interpreted from a public health perspective, strengthens the position of the consensus guidelines. Vaidya et al. reported that there was a substantial increased risk of finding a raised TSH with the presence of personal history of thyroid disease or other autoimmune disorders, thyroperoxidase antibodies, and family history of thyroid disorders. This observation is not surprising and supports the consensus guidelines’ position in recommending these factors as highly valuable for risk stratification (4). The key issue here is to evaluate the operating characteristics of this selective high-risk case finding approach (as opposed to universal screening) in detecting thyroid dysfunction, especially increased TSH. To do so, one must estimate the sensitivity, specificity, positive and negative predictive values (PPV & NPV, respectively) of the “test” i.e., in this case, the consensus guidelines recommended risk stratification approach. This can be performed by reorganizing the data available from table 2 of their report.     Raised TSH Low/Normal TSH Total High risk group 28 385 413 Low Risk group 12 1135 1147 Total 40 1520 1560 High risk individuals are those with personal history of thyroid or non-thyroidal autoimmune disorders or family history of thyroid disorders. The calculated sensitivity (28/40) of finding a case (i.e., all women with overt or subclinical hypothyroidism) based on high risk definition is 70%. This concurs with the authors’ conclusion that targeted high risk testing would only detect 70% of cases. The specificity (1135/1520) and PPV (28/413) are 73% and 68% respectively. However more importantly, the NPV is 1135/1147, i.e., 99%. In other words, a pregnant woman who does not have the “high risk” profile, there is only a 1% probability of finding an abnormal elevated TSH. Consequently, universal screening of all women,, include those at low risk according to the consensus guidelines, may not be fully justifiable. Once again, we wish also to applaud the efforts of the authors for what is probably one of the most extensively collected maternity databases of thyroid status. References 1. Vaidya B, Anthony S, Bilous M, Shields B, Drury J, Hutchison S, Bilous R. 2007. Detection of Thyroid Dysfunction in Early Pregnancy: Universal Screening or Targeted High-Risk Case Finding? J Clin Endo Metab 92:203-207 2. Brent GA. 2007. Diagnosing Thyroid Dysfunction in Pregnant Women: Is Case Finding Enough? J Clin Endo Metab 92:39-41 3. Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH, Franklyn JA, Hershman JM, Burman KD, Denke MA, Gorman C, Cooper RS, Weissman NJ. 2004. Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. JAMA 291:228-238 4. Gharib H, Cobin RH, Dickey RA. 1999. Subclinical Hypothyroidism during pregnancy:Position Statement from the American Association of Clinical Endocrinologists. Endocr Pract. 5:367-368