SUN-431 Case Finding Versus Routine Screening of Thyroid Dysfunction in Pregnancy

Abstract

Background: Thyroid dysfunction in pregnancy is associated several adverse outcomes. This has triggered a debate about whether universal screening should be implemented. Despite recommendations against universal screening, the clinical practice of many caregivers may differ. We aimed to assess the sensitivity of using targeted high-risk case finding for diagnosing thyroid dysfunction in pregnancy compared to routine screening in pregnant Saudi women, and to evaluate if gestational diabetes (GDM) specifically affected the risk. Methods: A cross-sectional study in two hospitals under the Ministry of National Guards Health affairs of Saudi Arabia; King Abdulaziz Hospital, Al-Ahsa, and Imam Abdulrahman bin Faisal Hospital, Dammam. Pregnant ladies attending the Family medicine, Obstetrics and Gynecology, and Endocrinology clinics in both hospitals were assessed by the caring physician based on a check list for risk stratification for thyroid dysfunction as per the 2012 Endocrine society clinical practice guidelines for management of thyroid dysfunction in pregnancy. Presence of one risk factor defined high risk. All patients had a routine serum TSH measured as universal screening is commonly practiced in both institutions, the physician doing the risk stratification was not aware of the TSH result. Sensitivity and specificity for the case finding approach was calculated using and abnormal TSH value as the gold standard for presence of thyroid dysfunction. The institutions lab reference TSH 0.35 – 4.94 mIU/L was used as cutoff. Results: 1571 pregnant women were included in the study; mean age 29.3± 6.2 years, 396 (23.5%) were primigravida. The mean TSH value was 1.898 ± 1.459 mlU/L. 1178 (75%) pregnant women had an indication for screening based on presence of at least one risk factor, of which 95 (8.1%) tested abnormal for TSH. 393 women had no risk factors, of which 379 (96.4%) had normal TSH, (Chi square 9.3, p-value 0.002). [Sensitivity 87.2%, (95%CI 79.4% – 92.8%), Specificity 25.9%, (95%CI 23.7% – 28.3%)]. Total abnormal TSH values was 109 (6.9%), 43 were abnormal high (i.e. hypothyroid); of which 40 screened positive by case finding approach [Sensitivity 93.02%, (95%CI 80.9% – 98.5%), Specificity 25.52%, (95%CI 23.4% – 27.8%)]. Moreover, 178 (11.3%) women screened positive for GDM at some stage in pregnancy out of which only 5 (2.8%) had an abnormal TSH value, while of the 1393 pregnant women who screened negative for GDM 1289 (92.5%) had a normal TSH value, (Chi square 5.3, p-value 0.02). [Sensitivity 4.6%, (95%CI 1.5% – 10.4%), Specificity 88.2%, (95%CI 86.4% – 89.8%)]. Conclusion: Targeted high-risk case finding predicts thyroid dysfunction in pregnant Saudi women with high sensitivity supporting its utility in screening our pregnant population. Gestational diabetes is highly prevalent in Saudi women, but does not increase risk of thyroid dysfunction in pregnancy.