The Discussion On Relationship Between Hypothyroidism And Hypertensive Disorders Complicating Pregnancy

Objective: Thyroid disorders are common endocrine disease,especially in reproductive women. The hypothalamus-pituitary-thyroid axis system during pregnancy is in a special status of stress and the thyroid hormones the pregnant produce is not only for the the production and metabolism of themselves but also for the growth of the fetus.So it is different from the characteristics of non-pregnancy. It is noticed that maternal thyroid dysfunction during pregnancy can lead to both obstetrical complications and adverse perinatal outcomes such as miscarrage, stillbirth, placental abruption,hypertensive disorders complicating pregnancy, cardiac dysfunction, intrauterine growth restriction, fetal distress and so on. Thyroid diseases during pregnancy are more common in to see in clinic, including pregnant women with hypothyroidism and hyperthyroidism, and clinical obstetric complications and adverse perinatal outcome is not uncommon. Therefore more attentions should be paid to changes in thyroid function during pregnancy and its effect on pregnancy.However, most of the thyroid diseases during pregnancy may be not obvious or have no specific clinical symptoms, the diagnosis relies mainly on laboratory tests, the most important of which is an indication of thyroid stimulating hormone (TSH) concentrations. Due to the special physiological changes during pregnancy, such as the emergence of the human chorionic gonadotropin (HCG) which has a same subunit with TSH and may play a similiar activity of TSH, at the same time it is under the negative feedback inhibition hypothalamus-pituitary axis, so that the serum TSH concentrations during pregnancy declined compared with the non-pregnant. There is no clear and unified thyroid hormones normal reference range during pregnancy in the world. Some people report that the TSH level declines during pregnancy, and suggest reducing the upper limit of TSH during pregnancy to enable the timely detection of patients with hypothyroidism during pregnancy to reduce the incidence of adverse events.It is now well known that the thyroid hormones may be able to dilate the peripheral vascular which significantly reduce vascular resistance, enhance myocardial contractive force, increase the heart rate to increase cardiac output. When hypothyroidism happens,things are totally different.That is the increased vascular resistance.Some research prompted hypothyroidism during women is an independent risk factor for hypertension diseases. And lower plasma protein concentration can lead to the reduction of plasma osmotic pressure,resulting in the edema of the tissues, which can affect the microcirculation.Thereby women with thyroid dysfunction during pregnancy may cause the hypertensive disease by affecting the concentration of the plasma protein.So hypothyroidism may be a risk factor of the hypertensive disorders during pregnancy. We do the research by the retrospective analysis of thyroid hormone levels and plasma protein concentration, obstetric complications and adverse perinatal outcomes, such as comparison, to study the thyroid pregnancy dysfunction on adverse effects of pregnancy between the pregnant women with abnormal and normal thyroid function group to explore the relationship among the thyroid dysfunction, plasma protein concentration and the hypertensive disorders .Methods: Retrospective analysis of hospital admission over the past two years of abnormal thyroid function of 27 cases of pregnant women as patients, with an average age (26.85±7.01) years of age; the same period of hospitalization in pregnant women with normal thyroid function in 19 cases as a control group, the average age (28.26±6.50) years old. Two groups have been excluded from chronic liver, kidney and heart disease. According to the diagnostic criteria of thyroid disease developed by The American Endocrine Society in 2000 ,the patients will be divided into cases of hypothyroidism (hypothyroidism) group and hyperthyroidism (hyperthyroidism) Group. We Compared the thyroid-associated hormone levels , plasma protein concentration, obstetric complications (such as hypertensive disorders complicating pregnancy, placental abruption, fetal distress, intrauterine growth restriction, etc.) and the perinatal outcome (pregnant weeks, birth weight, Apgar score, etc.) in the respective cases and controls and different sub-TSH (to 10, 5.6, 2.5 mU/L for the community), the obstetric complications and adverse pregnancy outcome incidence.Results: The hypothyroidism group TSH, FT3, FT4, ALB, TP were significantly lower than the control group, with statistically significant differences (p<0.05); the termination of gestation, birth weight were lower than the control group, (p <0.05); the complications and adverse perinatal outcome was significantly higher than that, (p<0.01), which contained hypertensive disorders in 8 cases, the occurrence rate 80 percent, significantly higher than the control group,(p<0.01).The Hyperthyroidism group TSH and FT3, FT4 levels were significantly lower than the control group (respectively p<0.05, p<0.01); the ALB, TP level was slightly lower than the control group, but there was no significant difference (p>0.05). This group had slightly less birth weight, termination of gestational age and higher perinatal mortality than the control group, but there is no statistical significance (p>0.05); The incidence of obstetric complications 58.8%, compared with the control group (p<0.05),in which hypertensive disorders complicating pregnancy 4 cases, with the incidence rate 23.53%, higher than the control, but the difference was not statistically significant (p>0.05).In different sub-TSH groups, the adverse pregnancy outcomes and complication rate of sTSH>10mU/L group is far higher than this sub-control group, which was a significant difference (p<0.01); but no statistical significance (p>0.05) to be compared with the other two groups.TSH5.6-10mU/L group, adverse pregnancy outcomes and higher complication rate were significant different (p<0.05), compared with the sub-control; So was the TSH2.5-5.6mU/L group, but only the incidence of complications was statistically significant (p<0.05).Conclusion: The terminal gestational age and birth weight are the important parameters for perinatal prognosis.We found both Hypothyroidism and hyperthyroidism are the risk factors of pregnancy, resulting in adverse events such as pregnancy adverse perinatal outcome and the incidence of obstetric complications increased; if we still use the TSH reference range of the non-pregnancy as a judge to determine whether thyroid function is normal,we may misdiagnose some patients with abnormal thyroid function,which thus increases the risk of adverse pregnant consequences. Prompted the establishment of pregnancy-specific levels of thyroid hormone-related normal range is essential.So it is necessary for us to establish a pregnancy-specific normal reference range of thyroid hormones ; The pregant women with thyroid hypofunction had decreased plasma protein concentration, the significantly increased occurrence of hypertension, which suggest that abnormal thyroid function during pregnancy may be proner to suffering from the hypertensive disorders.