One-step or two-step screening for thyroid diseases during early pregnancy: which is better?

Abstract

Objective To investigate the appropriate screening method for thyroid diseases during early pregnancy. Methods We collected information of 4 044 pregnant women who attended to the Department of Obstetrics and Gynecology of Peking University First Hospital from September 1, 2013 to September 30, 2014 for antenatal care and underwent one step screening for thyroid diseases in first trimester, which meant blood test for thyroid stimulating hormone(TSH), free thyroxine(FT4) and thyroid peroxidase antibody(TPOAb) at the same time. Simulation analysis was performed on these 4 044 women with two-step screening (TSH first and then FT4 and TPOAb if TSH was abnormal). The incidence, missed diagnosis rate, costs of screening, and outcomes of the missed diagnosed cases of women with thyroid diseases were compared between one-step and two-step screening based on the cutoff value determined by American Thyroid Association (ATA) or our hospital (0.23-4.08 mU/L). The positivel rate of TPOAb was compared among the three groups classified according to TSH value (≥0.1-<2.5 mU/L, ≥2.5-<4.08 mU/L and ≥4.08 mU/L). T-test, Chi-square test or Fisher's exact test were applied for statistical analysis. Results When the cutoff value of TSH was set at ≥0.1- 0.05), including fetal distress, gestational diabetes mellitus, preterm birth, fetal growth restriction, oligohydroamnios, polyhydroanmios, fetal death, gestational hypertension with pre-eclampsia, placental abruptio and neonatal asphyxia were reported although no standard treatment had been provided, no matter ATA recommendation or unique reference in our hospital was adopted. Conclusions We recommend the two-step method for thyroid function screening during early pregnancy. For the purpose of cost-saving, reduction of missed diagnosis rate and avoidance of overtreatment, the management protocol should be individualized for those women with TSH value between 2.5 mU/L and the normal reference value of our hospital during pregnancy. Key words: Pregnancy complications; Thyroid diseases; Physician's practice patterns; Pregnancy trimester, first