Frequency of subclinical hypothyroidism (SH) and autoimmune thyroiditis (AT) in pregnancy
Hernando Vargas Uricoechea
Background: The frequency of SH and AT in pregnancy is of the 3%, and diagnosis is determinant because of the high risk of complications (postpartum hemorrhage, abruptio placentae, gestational hypertension in the mother and disordered brain development and/or intrauterine growth retardation in the fetus).
Objective: Determine the frequency of SH and AT in 300 pregnant women.
Materials and methodology: About 300 pregnant women were screened. In accordance to gestation time the criterions of exclusion enclosed antecedents of replacement with thyroxine or previous thyroid disease. Blood samples were drawn for TSH, FT4, FT3 and TPO antibodies.
Results: From the 300 women, 120 (40%) were in first trimester; 88 (29.3%) were in second trimester and 92 (30.7%) were in third trimester. Prevalence of SH was found in 25 women (83%) of which 10 were diagnosed in the first trimester, 8 in the second trimester and 7 in the third trimester. All of the patients presented high levels of TSH with normal FT4 and FT3. The TPO antibodies were positive in 8 of the 10 women in the first trimester; 7 of the 8 in the second trimester and in 5 of the 7 in the third trimester. There was no difference in the TSH, FT4, FT3 and TPO antibody levels along of the studied trimesters (P=0.21).
Conclusion: (1) The prevalence of SH and AT can be higher than normally described, in our series it was of the 8.3%.
(2) The high prevalence of SH and AT in different populations can cause high frequency of maternal and fetal complications.