Thyroid Function During Pregnancy and The Postpartum Period: Iodine Metabolism and Disease States

Maternal factors in the origin of infantile hypertrophic pyloric stenosis: A population-based case-control study

In most patients affected by isolated infantile hypertrophic pyloric stenosis (IHPS) the etiology is largely unknown. Thus, the aim of this study was to estimate possible maternal risk factors in the origin of IHPS. The study samples included 241 cases with IHPS, 357 matched controls and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Exposures that had been medically recorded in prenatal maternity logbooks during the critical period of IHPS were evaluated separately. The findings of this case-control study suggested that--beyond the well-known robust male excess (85.5%)--maternal hyperthyroidism (OR with 95% CI: 4.17, 1.53-11.38) and oral nalidixic acid treatment (OR with 95% CI: 6.53, 3.03-14.06) associated with a higher risk for IHPS in their children. In conclusion, our findings suggest that cases with IHPS had mothers with a higher proportion of hyperthyroidism and nalidixic acid treatment during pregnancy.

Maternal hyperthyroidism increases the susceptibility of rat adult offspring to cardiovascular disorders

Suboptimal intrauterine conditions as changed hormone levels during critical periods of the development are considered an insult and implicate in physiological adaptations which may result in pathological outcomes in later life. This study evaluated the effect of maternal hyperthyroidism (hyper) on cardiac function in adult offspring and the possible involvement of cardiac Renin-Angiotensin System (RAS) in this process. Wistar dams received orally thyroxin (12 mg/L) from gestational day 9 (GD9) until GD18. Adult offspring at postnatal day 90 (PND90) from hyper dams presented increased SBP evaluated by plethysmography and worse recovery after ischemia-reperfusion (I/R), as evidenced by decreased LVDP, +dP/dT and -dP/dT at 25 min of reperfusion and by increased infarct size. Increased cardiac Angiotensin I/II levels and AT1R in hyper offspring were verified. Herein, we provide evidences that maternal hyperthyroidism leads to altered expression of RAS components in adult offspring, which may be correlated with worse recovery of the cardiac performance after ischemic insults and hypertension.

TSH receptor antibodies have predictive value for breast cancer - retrospective analysis

Background

Associations between breast cancer and thyroid disorders are reported in numerous studies. Relationships between thyroperoxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and breast cancer have been previously demonstrated. However, no analysis has been performed concerning an association between thyrotropin (TSH) receptor antibodies (TSHRAb) and breast cancer. The aim of the study was to evaluate the prevalence of breast cancer or benign breast tumors in patients with Graves’ disease and to analyze a possible relationship between Graves’ disease and these two groups of breast diseases with emphasis to epidemiology and laboratory findings.

Patients and methods

Clinical and laboratory details of 2003 women hospitalized for endocrine disorders were retrospectively analyzed, using an unpaired Student’s t-test, logistic regression analysis, χ² test of independence or the two-sided ratio comparison test.

Results

The coexistence of Graves’ disease and breast cancer was statistically significant. We observed TSHRAb and TgAb more frequently in patients with breast cancer. We found that TSHRAb is the only variable possessing predictive value for breast cancer.

Conclusions

The strong relationship between Graves’ disease and breast cancer is proposed. We suggest that TSHRAb could be described as a positive determinant of breast cancer. The present data call attention to the usefulness of screening for breast cancer in long-term follow-up of patients with autoimmune thyroid disorders, especially of those with Graves’ disease. Similarly, screening for autoimmune thyroid disorders should be performed in patients with nodular breast disease. Additionally, the article draws ideas for further research in order to develop targeted treatment for more successful outcome in patients with breast cancer.

Possible association between hyperthyroidism in pregnant women and obstructive congenital abnormalities of urinary tract in their offspring--a population-based case-control study

OBJECTIVE

The teratogenic potential of some antithyroid drugs is known, but the aim of the study was to estimate the risk of congenital abnormalities (CAs) in the offspring of pregnant women with hyperthyroidism with or without antithyroid drug treatment.

METHOD

Comparison of the occurrence of medically recorded hyperthyroidism who had malformed fetuses/newborns (cases) and who delivered healthy babies (controls) in the population-based Hungarian Case-Control Surveillance System of CAs, 1980-1996. Of 22,843 cases with congenital abnormalities, 71 (0.31%) while of 38,151 controls, 116 (0.30%) had mothers with hyperthyroidism. The rate of hyperthyroidism in the mothers of cases with different CAs and in the mothers of matched controls was compared.

RESULTS

Preeclampsia-eclampsia occurred more frequently in pregnant women with hyperthyroidism without antithyroid treatment. The analysis of specific groups of CAs showed an association between hyperthyroidism in pregnant women and obstructive defects of urinary tract in their children.

CONCLUSIONS

The lack of appropriate treatment of pregnant women affected with hyperthyroidism seems to be the major problem, because it would be necessary to prevent the hyperthyroidism related risks of pregnancy complications and CAs which exceed the risk of antithyroid medication in these pregnant women.

[Thyroid and pregnancy]

Pregnancy is associated with an increased requirement of hormone secretion by the thyroid, within the first weeks after conception. To this greater demand to occurs, pregnancy induces a series of physiological changes that affect thyroid function and, consequently, the tests of glandular function. For normal pregnant women living in areas with a sufficient supply of iodine, this challenge regarding the adjustment of thyroid hormone releases to this new state of equilibrium and its maintenance until the end of pregnancy it meets no difficulties. However, among women with impaired thyroid function due to some thyroid disease or among women residing in areas with an insufficient iodine supply, this does not occur. The management of thyroid dysfunction during gestation requires special considerations, since both hypothyroidism and hyperthyroidism can lead to maternal and fetal complications. In addition, thyroid nodules are detected at reasonable frequency among pregnant women, a fact that requires a differential diagnosis between benign and malignant growths during the pregnancy itself.

Thyroid medications during pregnancy

Euthyroid women experience dramatic changes in their thyroid physiology in order to accommodate the presence of placental and fetal tissues. These adaptations to the pregnant state make it crucial to develop reliable trimester-specific intervals for thyroid parameters. Use of non-pregnant reference intervals could lead to erroneous assessment of thyroid status in this rapidly changing hormonal environment. Only with a full appreciation of physiologic changes in thyroid parameters during a euthyroid pregnancy, can thyroid dysfunction be appropriately diagnosed and managed. Iodine sufficiency during pregnancy can be achieved with supplementation using a multivitamin. Both hypothyroidism and hyperthyroidism should be diagnosed using the appropriate reference intervals for pregnancy. Hypothyroid women are best treated with a specific brand of levothyroxine. Hypothyroidism should ideally be treated prior to conception. If newly recognized during pregnancy, it should be fully treated as early as possible. Frequent monitoring of thyroid status is essential as many women demonstrate an increased requirement for thyroid hormone during the first trimester. Although mild hyperthyroidism may be well tolerated during pregnancy, overt hyperthyroidism requires treatment. Thionamides are the mainstay of therapy. Following their initiation, close monitoring is required to avoid maternal and fetal hypothyroidism. There are occasional circumstances when other medical therapy or surgical therapy may be employed for hyperthyroidism. Thyroidectomy is generally safe in the second trimester in an appropriately prepared woman. There is limited data about the role and safety of oral contrast agents, iodine, amiodarone, and perchlorate. Radioiodine therapy is contradicted during pregnancy.

Thyroid disease and other endocrine disorders in pregnancy

Endocrine disorders, in particular, thyroid disorders, are common in pregnancy. The endocrine adaptation to pregnancy, need for adequate iodine supplementation, and thyroxine replacement are presented. In addition, autoimmune diseases of the thyroid and pituitary that may occur subsequent to the immune changes of pregnancy and the postpartum period are discussed. A brief account of the presentation of other endocrine disorders (ie, pituitary,parathyroid, calcium, adrenal and gonadal disorders) also is given, along with their evaluation and management.

Déficit de yodo y función tiroidea en una población de mujeres embarazadas sanas

BACKGROUND AND OBJECTIVE

Studies from Spain suggest that the intake of iodine in pregnant women is below nutritional requirements. This study was designed to determine iodine intake and its relation with thyroid volume during pregnancy in women from southeast Spain.

PATIENTS AND METHOD

A total of 520 healthy pregnant women were studied during the full three trimesters of their pregnancy. A control group was composed of 373 non-pregnant women. The following variables were measured: TSH, FT3, FT4, thyroglobulin, antiperoxidase antibodies, urinary iodine levels, and thyroid volume.

RESULTS

Median urinary iodine levels were below 100 g/l in the controls and the pregnant women during their first trimester. These levels rose progressively and significantly over the second and third trimesters. Thyroid volume increased during the second and third trimesters compared with the first. TSH levels were lower during the first trimester compared to controls, and increased significantly during the third trimester. FT4 levels fell significantly during the third trimester. There was a significant negative correlation between TSH levels and thyroid volume (r = 0.22; p = 0.005).

CONCLUSIONS

Iodine intake in pregnant women in Malaga is low. The results suggest a deficit in thyroid function secondary to iodine deficiency, which is worsened as pregnancy advances. The data support the convenience of systematic administration of an iodine supplement in healthy pregnant women.