Detection of thyroid dysfunction in early pregnancy: Universal screening or targeted high-risk case finding?
BACKGROUND
Maternal subclinical hypothyroidism during pregnancy is associated with various adverse outcomes. Recent consensus guidelines do not advocate universal thyroid function screening during pregnancy but recommend testing high-risk pregnant women with a personal history of thyroid or other autoimmune disorders or with a family history of thyroid disorders.


OBJECTIVE
The objective of the study was to assess efficacy of the targeted high-risk case-finding approach in identifying women with thyroid dysfunction during early pregnancy.


METHODS
This was a single-center cohort study. PATIENTS/OUTCOME MEASURES: We prospectively analyzed TSH, free T4 and free T3 in 1560 consecutive pregnant women during their first antenatal visit (median gestation 9 wk). We tested thyroperoxidase antibodies in 1327 (85%). We classified 413 women (26.5%), who had a personal history of thyroid or other autoimmune disorders or a family history of thyroid disorders, as a high-risk group. We examined whether testing only such a high-risk group would pick up most pregnant women with thyroid dysfunction.


RESULTS
Forty women (2.6%) had raised TSH (>4.2 mIU/liter). The prevalence of raised TSH was higher in the high-risk group [6.8 vs. 1% in the low-risk group, relative risk (RR) 6.5, 95% confidence interval (CI) 3.3-12.6, P < 0.0001]. Presence of personal history of thyroid disease (RR 12.2, 95% CI 6.8-22, P < 0.0001) or other autoimmune disorders (RR 4.8, 95% CI 1.3-18.2, P = 0.016), thyroperoxidase antibodies (RR 8.4, 95% CI 4.6-15.3, P < 0.0001), and family history of thyroid disorders (RR 3.4, 95% CI 1.8-6.2, P < 0.0001) increased the risk of raised TSH. However, 12 of 40 women with raised TSH (30%) were in the low-risk group.


CONCLUSIONS
Targeted thyroid function testing of only the high-risk group would miss about one third of pregnant women with overt/subclinical hypothyroidism.
Vaidya
Bijay
B
Department of Endocrinology, Royal Devon, Exeter Hospital, Exeter EX2 5DW, United Kingdom. bijay.vaidya@pms.ac.uk
Anthony
Sony
S
Bilous
Mary
M
Shields
Beverley
B
Drury
John
J
Hutchison
Stewart
S
Bilous
Rudy
R
D000328:Adult; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011261:Pregnancy Trimester, First; D012016:Reference Values; D012306:Risk; D013959:Thyroid Diseases / Q000175:diagnosis*; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use
D013972:Thyrotropin; D013974:Thyroxine