Thyroid Status In Pregnancy Research Articles

Thyroid status in pregnancy: Comparison of thyroid function abnormalities in women with and without a history of miscarriage or stillbirth.

To evaluate thyroid function tests (TFTs) during pregnancy in women with previous history of miscarriage or stillbirth. A cross-sectional study was carried out at the department of Obstetrics & Gynaecology and Endocrinology, Lady Reading Hospital, Peshawar from February 2021 to March 2022. All multigravida women attending the antenatal clinics were included using consecutive sampling. These women were placed into two groups, Group-A comprised of women with no prior history of miscarriages or stillbirths, and those with a history of foetal death during previous pregnancies were assigned Group-B. Free T4, thyroid stimulating hormone (TSH) and anti-thyroid peroxidase (TPO) antibodies were measured and the former two were used to label patients with thyroid dysfunction. A total of 139 multigravida women were included in the study. About 43% of the women had a history of miscarriages or stillbirths. Thyroid dysfunction was observed overall in 36.69 % women, of whom 25.18% had sub-clinical hypothyroidism, 6.47% had hypothyroidism and 5.04 % were sub-clinical hyperthyroid. Women in Group-B had more thyroid functions abnormalities compared to Group-A (p<0.05). Moreover, there was significant difference in median TSH and freeT4 between the groups (p<0.001). Overall, thyroid dysfunction was found in 66.67% of patients who had a history of foetal death. In pregnant women with a history of miscarriage or abortion, thyroid functions abnormalities are common therefore routine thyroid testing is advised in pregnant women to prevent adverse perinatal outcomes.

Preconception Management of Hyperthyroidism and Thyroid Status in Subsequent Pregnancy: A Population-Based Cohort Study.

Optimal thyroid status in pregnancy is essential in reducing the risk of adverse outcomes. The management of hyperthyroidism in women of reproductive age poses unique challenges and it is unclear how preconception treatment strategies impact on thyroid status in subsequent pregnancy. We aimed to determine trends in the management of hyperthyroidism before and during pregnancy and to assess the impact of different preconception treatment strategies on maternal thyroid status. We utilized the Clinical Practice Research Datalink database to evaluate all females aged 15-45 years with a clinical diagnosis of hyperthyroidism and a subsequent pregnancy (January 2000 to December 2017). We compared thyroid status in pregnancy according to preconception treatment, namely, (1) antithyroid drugs up to or beyond pregnancy onset, (2) definitive treatment with thyroidectomy or radioiodine before pregnancy, and (3) no treatment at pregnancy onset. Our study cohort comprised 4712 pregnancies. Thyrotropin (TSH) was measured in only 53.1% of pregnancies, of which 28.1% showed suboptimal thyroid status (TSH >4.0 mU/L or TSH <0.1 mU/L plus FT4 >reference range). Pregnancies with prior definitive treatment were more likely to have suboptimal thyroid status compared with pregnancies starting during antithyroid drug treatment (odds ratio 4.72, 95% CI 3.50-6.36). A steady decline in the use of definitive treatment before pregnancy was observed from 2000 to 2017. One-third (32.6%) of first trimester carbimazole-exposed pregnancies were switched to propylthiouracil while 6.0% of propylthiouracil-exposed pregnancies switched to carbimazole. The management of women with hyperthyroidism who become pregnant is suboptimal, particularly in those with preconception definitive treatment, and needs urgent improvement. Better thyroid monitoring and prenatal counseling are needed to optimize thyroid status, reduce teratogenic drug exposure, and ultimately reduce the risk of adverse pregnancy outcomes.

CHANGES IN THE PHYSIOLOGY OF THE THYROID GLAND IN PREGNANCY AND THE NEED FOR TRIMESTER-SPECIFIC REFERENCE VALUES IN THYROID STATUS: A REVIEW

Pregnancy is a unique state of the female organism in which occur physiological changes that arenecessary to maintain the pregnancy. To be able to respond to the increased metabolic needs of pregnancy and tomaintain an adequate level of thyroid hormones in the blood, the thyroid gland responds with changes in its functionand anatomy as well. Changes in thyroid function are mainly associated with increased levels of thyroxine-bindingglobulins in the blood. Their level increases as a result of estrogen stimulation in pregnancy and they are synthesizedin the liver. Changes in the physiology of the thyroid gland during pregnancy also occur as a result of stimulation ofthe TSH receptors of the gland by the human chorionic gonadotropin hormone (hCG) which is secreted by theplacental trophoblast.Due to the difference in the physiology of the thyroid gland in and outside of pregnancy, a special interpretation ofthe results of functional thyroid tests is required. Changes in hormone values are transitory, especially expressed inthe first trimester of pregnancy. A healthy pregnant patient without thyroid pathology or disease compensates forthose changes and a sufficient amount of thyroid hormones is produced. The presence of thyroid hormones in anoptimal concentration in the blood maintains a successful pregnancy and secures normal neurological developmentof the fetus. Diseases of the thyroid gland lead to a decrease its compensatory ability during pregnancy and thecontributes to the inability to respond to the increased metabolic needs that follow.The motive for this paper are the pregnant patients with undiagnosed or unrecognized thyroid gland diseases beforepregnancy, where we encounter conditions when the thyroid gland cannot respond to the physiological changes thatoccur. One of the negative outcomes of this condition can be spontaneous pregnancy loss in the first trimester.Therefore, a special interpretation of the thyroid status in pregnancy is needed and the introduction of constantreference values that will apply only to pregnancy.World recommendations designate reference values for TSH and thyroid hormones respectively for each trimester ofpregnancy, the so-called trimester-specific reference values. In case of absence of trimester-specific referencevalues, there are recommendations regarding the special interpretation of thyroid function tests and reference values;as well as recommendations for using adjusted values according to demographic characteristics that will apply to alltrimesters. This review of literature recommendations would help in the management of patients in order to achievean optimal serum level of thyroid-stimulating hormone and achieve a successful pregnancy, thus imposing the needto introduce recommendations in our laboratories for thyroid analysis values specific to pregnancy, which will differfrom those for the non-pregnant population

Hyperthyroidism during pregnancy--the role of measuring maternal TSH receptor antibodies and foetal ultrasound monitoring.

To evaluate the usefulness of measuring maternal anti-TSH receptor antibodies (TRAbs) and foetal ultrasound (US) monitoring in cases of current or past maternal hyperthyroidism. 77 pregnant women suffering from hyperthyroidism or with a history of Graves' hyperthyroidism were observed prospectively. Maternal serum TSH, fT4, fT3, TRAbs, and foetal US were performed at baseline and repeated every 2-4 weeks when needed. Neonatal thyroid status was assessed based on serum TSH, fT4 and fT3 obtained in the first days of life. 35 women were diagnosed with gestational hyperthyroidism and 42 with Graves' disease; among them 26 had current and 16 past hyperthyroidism. Foetal and neonatal thyroid dysfunction occurred only in cases of maternal Graves' disease: nine (21%) and three (7%), respectively. Active maternal Graves' hyperthyroidism and TRAbs elevated at least five times above the upper normal limit predisposed to foetal hyperthyroidism. Maternal anti-thyroid drug therapy (ATD) and low TRAbs and fT4 were the risk factors of foetal hypothyroidism. Abnormal foetal thyroid sonogram was the only sign of foetal thyroid dysfunction. Four patients (9.5%) had high TRAbs in the 3rd trimester (10.8-29.9 IU/mL), but neither foetal nor neonatal thyroid dysfunctions were noted. In the cases of maternal Graves' disease, foetal thyroid dysfunction occurs more often than commonly assumed. Foetal thyroid US is a valuable tool in early diagnosis and monitoring of the foetal thyroid status in pregnancy complicated by maternal Graves' disease. The evaluation of biological activity of maternal TRAbs may be helpful in prenatal diagnosis in some cases.

Prevalance and fetomaternal outcome of thyroid disorder in pregnanacy

Background: Thyroid diseases are the commonest endocrine disorders affecting women of reproductive age group and hence constitute the commonest endocrine disorder in pregnancy also. It has long been recognized that maternal thyroid hormone excess or deficiency can influence the outcome for mother and fetus at all stages of pregnancy as well as interfere with ovulation and fertility. Thyroid dysfunction is often overlooked in pregnant women because of the nonspecific symptoms and the hyper metabolic state of pregnancy. Hence thyroid function test becomes essential to know the thyroid status in pregnancy and also to detect the subclinical disease. Aims & Objective: To establish the prevalence and effect of thyroid disorder on pregnancy outcome. Materials and Methods: The study is an observational study carried on 100 women coming for antenatal check-up in Private hospital, Ahmedabad from January 2011 to January 2012. All women who were included in this study were followed from 11-14 weeks of pregnancy up to delivery. Results: It was observed that the maximum numbers of patients were in 21– 25 years (52%) age group. Euthyroid (87%), hyperthyroid (1%), subclinical hyperthyroid (2%), hypothyroid (2%), and subclinical hypothyroid (8%) cases were detected. Neonatal jaundice developed in all Hyperthyroid patient, 50% (1/2) of patients with Subclinical hyperthyroidism, 50% (1/2) of patients with Hypothyroidism, 75% (6/8) of patients with Subclinical Hypothyroidism and 48.27% (42/87) of patients with Euthyroid. Conclusion: Gestational age specific reference intervals are of utmost importance by which clinicians can reliably evaluate thyroid function and monitor thyroxine replacement therapy in pregnant women. TPOAb (Thyroid peroxidase Antibody) positive patients are associated with an increased risk of abortion and these infants are more often born preterm. TSH is the hallmark in detection of hypothyroid as well hyperthyroid so TSH should be included in the list of routine investigations done in all antenatal women in first trimester. If TSH values are abnormal then FT3, FT4 and TPOAb need to be checked.

Management of hypothyroidism in pregnancy

Examine recent studies on the assessment of thyroid status in pregnancy, approach to thyroid testing, the spectrum of hypothyroidism in pregnancy, and strategies for thyroid replacement in women with known hypothyroidism. Trimester-specific references range for thyroid-stimulating hormone (TSH) and free thyroxine in pregnancy must take into account iodine and thyroid autoantibody status, race, BMI, as well as other factors. Thyroid testing of only those pregnant women at increased risk for thyroid disease, case finding, will miss 30-80% of women with thyroid disease. Subclinical hypothyroidism is associated with an increasing number of adverse effects including infertility, miscarriage, preterm delivery, and breech presentation at birth. Many pregnant women with known hypothyroidism have an out-of-range TSH at the time of confirmed pregnancy. A variety of strategies are effective at keeping serum TSH normal during pregnancy including preconception increase in thyroxine, increase in thyroxine dose at the time pregnancy is confirmed, or making adjustments based on serum TSH monitoring. Evaluation of thyroid status in pregnancy requires an understanding of pregnancy-associated changes in thyroid function tests and how they vary by trimester. The spectrum of hypothyroidism in pregnancy includes isolated thyroid peroxidase antibody positivity, isolated hypothyroxinemia, subclinical and overt hypothyroidism. These patterns, in some situations, may be related to iodine status, selenium status, or underlying thyroid disease. There are a variety of approaches to management of thyroxine replacement in known hypothyroid women at the time of pregnancy that are all effective at maintaining a normal range during pregnancy.

Thyroidology and public health: The challenges ahead

Thyroidology and public health: The challenges ahead

Pharmacokinetics and Pharmacotherapy of Thionamides in Pregnancy

Hyperthyroidism occurs in approximately 1 in every 1000 to 2000 pregnancies. Although the signs and symptoms of the disease are similar in the pregnant and nonpregnant patient, the complications of hyperthyroidism can have even more profound consequences for the mother and fetus during gestation. These include maternal heart failure, preeclampsia, miscarriage, and preterm labor; as well as fetal loss and low birth weight. Furthermore, thyroid function and laboratory testing for hyperthyroidism are altered in pregnancy. The gestational increase in thyroid size, increased thyroid-binding globulin levels, increased serum total T4 and total T3 levels, and decreased thyroid stimulating hormone levels often confuses the evaluation of the thyroid status in pregnancy. Worldwide, the thionamides-propylthiouracil, methimazole, and carbimazole-have been used in pregnancy for the treatment of hyperthyroidism. However, propylthiouracil has been the drug of choice in the United States because it is believed to have less potential to induce fetal/neonatal hypothyrodism, to cross the placenta and into breast milk to a lesser degree, and to be less teratogenic than methimazole or carbimazole. None of the above have been substantiated in more recent studies. The pharmacokinetics of the thionamides in the pregnant and nonpregnant states, as well as the pharmacotherapeutic recommendation for hyperthyroidism will be reviewed.

Maternal thyroid function: interpretation of thyroid function tests in pregnancy.

Thyroid status is frequently assessed during pregnancy, both to evaluate suspected thyroid abnormalities, and to monitor the status, of pre-existing thyroid disease. However, the production, circulation, and disposal of thyroid hormone are all altered in pregnancy. Interpretation of thyroid function studies in the pregnant patient must be performed based on an understanding of the normal physiologic changes at each stage of pregnancy. Examples of pregnancy-associated changes include, estrogen-stimulated increase in serum thyroxine binding globulin, chorionic gonadotropin stimulated T4 and T3 production from the thyroid gland, and accelerated degradation of thyroid hormone by the placenta. The serum-TSH alone is usually not adequate to assess thyroid status in pregnancy, and the various conditions that can effect this measurement are described. The pattern of thyroid studies in pregnancy is important in diagnosing thyroid disease, and it may indicate physiologic adaptations to optimize maternal thyroid status for fetal development.

Effect of maternal thyroid autoantibodies and post-partum thyroiditis on the fetus and neonate

Thirty-five pregnant women with thyroid antibodies were followed during pregnancy and 12 month post partum. Twenty antibody-negative women served as controls and none of these developed postpartum thyroiditis in contrast to 12 of 35 antibody-positive women. Umbilical cord blood was collected at birth for measurements of thyroid antibodies, and blood samples for measurements of thyroid hormones were obtained at 5 and 30 days of age in the infants together with a clinical examination. There were no differences between the infants of antibody-positive and -negative mothers or the infants of those who developed postpartum thyroiditis with regard to gestational age at birth, birth weight, birth length or Apgar score, and no difference in thyroid function of the mothers and infants. However, serum TSH level was significantly higher in mothers who subsequently developed postpartum thyroiditis. Furthermore, a significantly lower growth during the first 30 days of life was observed in their infants. Our observations suggest a relationship between the maternal thyroid status in pregnancy and early growth in infancy.

Free thyroid hormone index, thyroid hormone/thyroxin-binding globulin ratio, triiodothyronine uptake, and thyroxin-binding globulin compared for diagnostic value regarding thyroid function.

The thyroid hormone/thyroxin-binding globulin (TBG) ratio and the free thyroid hormone index (FTI) were compared in 372 subjects classified according to age, sex, and biochemical and clinical findings. Age-related variations in thyroid function tests were investigated, as was the relationship between triiodothyronine uptake and TBG. Men, but not women, showed significant age-dependent changes in concentrations of thyroid hormones. FTI was as good as the thyroid hormone/TBG ratio in hyperthyroidism and was a better index of thyroid status in pregnancy, TBG deficiency, and hypothyroidism. In addition, the triiodothyronine uptake correlated extremely well with TBG (r = -0.95, p less than 0.001) and was very efficient in detecting decreased and significantly increased concentrations of TBG. I conclude that FTI is a better discriminator of functional status of the thyroid over a wider range of TBG values than is the thyroid hormone/TBG ratio. Further, the triiodothyronine uptake test produced diagnostic information equivalent to that of TBG estimation and thus should not be replaced in routine use.

THYROID STATUS IN PREGNANCY AND IN WOMEN TAKING ORAL CONTRACEPTIVES

PROTEIN-BOUND iodine and the uptake of 131I-triiodothyronine by resin have been measured in a group of pregnant women, in women taking 'Ovulen' and in a control group of healthy volunteers. From these data a free-thyroxine factor, which is proportional to the concentration of free thyroxine in the serum, has been calculated. Values for the free-thyroxine factor in pregnancy and in women taking ovulen were within the range for euthyroid individuals. These results suggest that thyroid status is normal in women taking œstrogen/ progestogen compounds. The free-thyroxine factor may be used to assess thyroid status in pregnancy and in women taking oral contraceptives.