Thyroid Screening in Early Pregnancy: Pros and Cons.

Peter N Taylor,Thinzar Min,Stamatios Zouras,Kalyani Nagarahaj,John H Lazarus,Onyebuchi Okosieme

doi:10.3389/fendo.2018.00626

Abstract

Universal thyroid screening in pregnancy is a key debate in thyroidology and obstetrics. It is well-established that thyroid hormones are essential for maintaining pregnancy and optimal fetal development. Thyroid dysfunction is common in women of child-bearing age and also results in substantial adverse obstetric and child neurodevelopmental outcomes. Furthermore, thyroid dysfunction is readily diagnosed with reliable blood tests and easily corrected with inexpensive and available treatments. Screening only high-risk patients appears to miss the majority of cases and economic models show that compared to high-risk screening, universal screening is cost effective even if only overt hypothyroidism was assumed to have adverse obstetric effects. As a result, several countries now implement universal screening. Opponents of universal thyroid screening argue that asymptomatic borderline thyroid abnormalities such as subclinical hypothyroidism and isolated hypothyroxinemia form the bulk of cases of thyroid dysfunction seen in pregnancy and that there is a lack of high quality evidence to support their screening and correction. This review critically appraises the literature, examines the pros and cons of universal thyroid screening using criteria laid down by Wilson and Jungner. It also highlights the growing evidence for universal thyroid screening and indicates the key challenges and practicalities of implementation.

Highlights

Thyroid hormones are essential for maintaining pregnancy and optimal fetal development [1, 2]
Subclinical hypothyroidism occurs in 2–3% of pregnancies [1, 16] and the prevalence of isolated hypothyroxinemia, defined as a normal TSH with FT4 below the 2.5 percentiles occurs in around 2% of pregnancies [19]
We have examined the pros and cons of universal thyroid screening in early pregnancy using the template set by Wilson and Jungner

Summary

INTRODUCTION

Thyroid hormones are essential for maintaining pregnancy and optimal fetal development [1, 2]. We appraise the potential benefits and drawbacks of universal thyroid screening in early pregnancy using the Wilson and Jungner criteria [17] (Box 1) It is well-established that overt thyroid dysfunction is an important health condition in pregnancy. Women with thyroid dysfunction suffer an increased risk of adverse pregnancy outcomes an association which is well-established for overt thyroid dysfunction but is seen with subclinical hypothyroidism [26]. In a prospective controlled trial, systematic screening and correction of gestational subclinical hypothyroidism significantly reduced adverse pregnancy events in the sub-group of women classified as low risk for thyroid disease [29]. Levothyroxine is the accepted treatment for overt hypothyroidism its benefits in gestational subclinical thyroid dysfunction remains uncertain. The overall costs of establishing a universal screening programme will need to be carefully considered and will need to incorporate the costs of personnel training, public education, establishment of healthcare infrastructure, and the burden of over-diagnosis and over-treatment

DISCUSSION

Findings

Continuing Process

CONCLUSION