Association Between Hypothyroidism And Preeclampsia

Objective: To investigate the alteration of hypothyroidism in patients with preeclampsia(PE), and explore the relationship with disease severity as well as with maternal-fetal outcomes.Methods: We retrospectively analyzed 499 cases of pregnant women who got obstetric examination and hospital delivery at the Obstetrics Clinic of the Second Hospital of Hebei Medical University in Jan. 2012 to Feb. 2015, in which 349 cases were diagnosed PE, while 150 pregnant women of normal control group were enrolled in match of the age, motherhood similar third trimester at the same time. Exclusion involved the diseases and conditions before pregnancy: hypertension, diabetes, heart disease, liver and kidney dysfunction history; hyperthyroidism, hypothyroidism, subclinical hypothyroidism and polycystic ovary syndrome, pituitary, adrenal and other endocrine diseases; pregnancy history of thyroid surgery; this pregnancy with gestational hypertension, eclampsia, chronic hypertension complicated by PE, chronic hypertension in pregnancy; bigeminal or multifetal pregnancies; elderly primiparas. PE diagnostic criteria were based on Xie Xing, Xun Wenli 8th edition "Obstetrics and Gynecology" naming and classification, and 349 cases of PE were divided into three groups: early-onset severe preeclampsia(SPE) 182 cases, late-onset SPE 106 cases, late-onset mild preeclampsia(MPE) 61 cases. The diagnostic criteria for thyroid function during pregnancy were based on Chinese Medical Association Endocrinology Branch, Chinese Medical Association of Perinatal Medicine Branch edited 2012 version of "pregnancy and postpartum thyroid disease diagnosis and treatment guidelines", and all patients were grouped according to the types of thyroid dysfunction. Blood samples were extracted from 499 cases of pregnant women under fasting conditions, chemiluminescence was used to detect serum thyroid stimulating hormone(TSH),free thyroxine(FT4),three free triiodothyronine(FT3) levels, and immunochemiluminometric assays was used to quantitative detection of thyroid peroxidase antibody(TPOAb) in serum. Statistic analysis was performed for thyroid dysfunction group in early-onset SPE, late-onset SPE, late-onset MPE and control group. As a result, the small sample size of hyperthyroidism(including clinical hyperthyroidism and subclinical hyperthyroidism), low thyroxinemia alone and the positive rate of TPOAb showed no representativeness within overall conditions, so we made hypothyroidism as a representative accounted for the vast majority of thyroid dysfunction patients in early-onset SPE, late-onset SPE, late-onset MPE and control group in the subsequent study. TSH, FT4, FT3, TPOAb, systolic blood pressure, diastolic blood pressure, 24-hour urinary protein quantitation were detected for hypothyroidism group in early-onset SPE, late-onset SPE, late-onset MPE and control group. The investigation was conducted on the relationship among TSH, systolic blood pressure, diastolic blood pressure, 24-hour urinary protein quantitation. The relationship between hypothyroidism and maternal-fetal outcome was explored in early-onset SPE, late-onset SPE, late- onset MPE. SPSS21.0 statistical software was used, ANOVA analysis of variance, rank sum test, Pearson correlation coefficient and chi-square test were in choice, P<0.05 represented statistically significant difference.Results: In terms of thyroid dysfunction types, the rates of hypothyroidism(including clinical hypothyroidism and subclinical hypothyroidism) in early-onset SPE, late-onset SPE, late-onset MPE groups were higher than that of the control group, the difference was statistically significant(P<0.05). In the subsequent study, PE was divided into early-onset SPE group with hypothyroidism(78 cases), late-onset SPE group with hypothyroidism(51 cases), late-onset MPE group with hypothyroidism(19 cases), and control group with hypothyroidism without PE(33cases). The levels of TSH and blood pressure in early-onset SPE hypothyroidism group, late-onset SPE hypothyroidism group were higher than those of hypothyroidism control group without PE, the difference was statistically significant(P<0.05). Meanwhile, the blood pressure in early-onset SPE hypothyroidism group and late-onset SPE hypothyroidism group was higher than that in late-onset MPE hypothyroidism group, the difference was statistically significant(P<0.05). The levels of FT4, FT3 and the negative rates of TPOAb among 4 groups showed no significant differences(P>0.05). 24-hour urinary protein quantitation was compared between the three hypothyroidism PE groups, and the results showed significantly differences(P<0.05). Correlation analysis indicated: the level of TSH in PE positively correlated with 24-hour urinary protein quantitation(r=0.132, P=0.047), also with diastolic blood pressure(r=0.173, P=0.036), not as to systolic blood pressure(r=0.035,P=0.676) or TPOAb(r=0.115,P=0.131). In terms of the maternal outcomes, the incidence rates of premature birth and cesarean in PE hypothyroidism group were higher than those in control hypothyroidism group without PE, the difference was statistically significant(P<0.05), as well as the difference between early-onset SPE and late-onset SPE, however in PE complications, the difference was not statistically significant(P>0.05). In terms of the perinatal outcome of infants, the incidence rates of live births and 1 minute Apgar score 8 to 10 point in early-onset SPE hypothyroidism group were lower than those in control hypothyroidism group without PE, the difference was statistically significant(P<0.05), while birth gestational age and birth weight in early-onset SPE hypothyroidism group and late-onset SPE hypothyroidism group was lower than that in control hypothyroidism group without PE, the difference was statistically significant(P<0.05), and the incidence rates of transfer to the neonatal intensive care unit(NICU) in early-onset SPE hypothyroidism group and late-onset SPE hypothyroidism group was higher than that in control hypothyroidism group without PE. Meanwhile, birth gestational age and birth weight in early-onset SPE hypothyroidism group was lower than that in late-onset PE hypothyroidism groups,the incidence of transfer to the neonatal intensive care unit(NICU) in early-onset SPE hypothyroidism was higher than that in late-onset PE hypothyroidism groups, the difference was statistically significant(P<0.05).Conclusion: The incidence rate of hypothyroidism in preeclampsia was higher than that in normal pregnancy. Hypothyroidism related to the severity of preeclampsia. We should emphasis on thyroid function screening in preeclamptic pregnancies.