Serial in utero ultrasonographic measurements of the fetal thyroid: a new complementary tool in the management of maternal hyperthyroidism in pregnancy

Thyroid autoantibodies

Thyroid-stimulating hormone (TSH) receptor antibody (TSH-R-Ab or TRAb) testing plays a pivotal role in arriving at the aetiological diagnosis in patients with thyrotoxicosis. A positive test establishes the diagnosis of Graves' disease (GD) while a negative result in conjunction with imaging studies supports other possible aetiologies. In patients with GD, TRAb levels at diagnosis and at the time of withdrawal of antithyroid drugs can identify patients who are unlikely to achieve remission and guide clinical management decisions. We provide an algorithm that incorporates TRAb in the decision-making process for the management of thyrotoxicosis. The utility of TRAb in predicting the risk of fetal and neonatal thyroid dysfunction is established and widely accepted in guidelines. TRAb may also help in the diagnosis of Graves' orbitopathy, especially in euthyroid or hypothyroid patients and its role in guiding its management is evolving as a useful adjunct to the clinical parameters used in making therapeutic decisions.Anti-thyroid peroxidase antibodies (TPOAb) and anti-thyroglobulin antibodies (TgAb) indicate thyroid autoimmunity. The most common use of TPOAb is to identify patients at a higher risk of progression to treatment-requiring hypothyroidism. They also aid the diagnosis of immune thyroiditis and Hashimoto's encephalopathy. Thyroglobulin measurement is used to help guide differentiated thyroid cancer treatment. TgAb is used as an accompanying test with thyroglobulin measurement as its presence can interfere with the thyroglobulin assay. A negative TgAb result reduces the likelihood of, but does not exclude, interference with thyroglobulin assay.

Follow-up of infants born to mothers with Graves' disease

INTRODUCTION

The prevalence of neonatal hyperthyroidism (HN) due to maternal Graves Disease (GD) ranges from 0.1 to 2.7%. It may occur in pregnant women with the following: active DG, after treatment with radioactive iodine, anti-thyroid or thyroidectomy or with a previous child with hyperthyroidism. The aim of our observational study was to evaluate the follow-up of infants born to mothers with GD at a Tertiary Hospital prior to the implementation of a follow-up protocol.

METHODS

This was a retrospective observational study using data from the medical records of mothers with a diagnosis of GD and their newborns from January 2013 until May 2018. Newborns were divided into two groups: high and low risk for NH according to maternal TRAb, third trimester treatment and signs of fetal hyperthyroidism.

RESULTS

We identified 31 newborns, 58% female; 87% high risk. In none of the newborns was umbilical cord blood collected. In the high risk group, 22% had thyroid function evaluation at day-1, one patient presented with hyperthyroidism and 82% were asymptomatic. Considering the cases with an insufficient blood sample for analysis, 9 consultations would have been spared. We found a significant delay in obtaining the high-risk group results which would have spared 10 appointments. A positive correlation was found between age at outpatient clinic discharge and the number of appointments and the maternal TRAb titer.

CONCLUSION

The correct surveillance of pregnancy and newborns with identification of those at high risk is essential to avoid unnecessary consultations and blood analyses that increase parental anxiety and hospital costs. Consequently, a multidisciplinary protocol was created to standardize the approach.

Management of Severe Graves' Hyperthyroidism in Pregnancy Following Immune Reconstitution Therapy in Multiple Sclerosis

CONTEXT

Alemtuzumab (ALZ), a CD52 monoclonal antibody, is highly efficacious in multiple sclerosis; however, side effects are common. Autoimmune thyroid disease (Graves' disease and Hashimoto thyroiditis) is a well-known complication of ALZ. Treatment of ALZ-induced Graves' disease can be challenging, and even more difficult during pregnancy.

CASE DESCRIPTION

We present a case of severe ALZ-induced Graves' disease with a rapid increase in thyrotropin receptor antibodies (TRAb 240 IU/L) and thyrotoxicosis in early pregnancy. Treatment with high doses of antithyroid medication was needed. There was high risk of both fetal and neonatal thyrotoxicosis. Serial fetal sonography showed normal development. The newborn baby presented high levels of TRAb (240 IU/L) and developed neonatal thyrotoxicosis on day 8. Adequate monitoring, treatment, and follow-up of the newborn baby ensured normal thyroid function until disappearance of TRAb 6 weeks after birth.

CONCLUSION

Multiple sclerosis patients treated with ALZ may develop severe Graves' disease with an increased risk of both fetal and neonatal thyrotoxicosis. Close follow-up with a multidisciplinary approach is needed to ensure a healthy outcome.

Testing, Monitoring, and Treatment of Thyroid Dysfunction in Pregnancy

Both hyperthyroidism and hypothyroidism can have adverse effects in pregnancy. The most common causes of thyrotoxicosis in pregnancy are gestational transient thyrotoxicosis and Graves' disease. It is important to distinguish between these entities as treatment options differ. Women of reproductive age who are diagnosed with Graves' disease should be counseled regarding the impact of treatment options on a potential pregnancy. Although the absolute risk is small, antithyroid medications can have teratogenic effects. Propylthiouracil appears to have less severe teratogenicity compared to methimazole and is therefore favored during the first trimester if a medication is needed. Women should be advised to delay pregnancy for at least 6 months following radioactive iodine to minimize potential adverse effects from radiation and ensure normal thyroid hormone levels prior to conception. As thyroid hormone is critical for normal fetal development, hypothyroidism is associated with adverse obstetric and child neurodevelopmental outcomes. Women with overt hypothyroidism should be treated with levothyroxine (LT4) to a thyrotropin (thyroid-stimulating hormone; TSH) goal of <2.5 mIU/L. There is mounting evidence for associations of maternal hypothyroxinemia and subclinical hypothyroidism with pregnancy loss, preterm labor, and lower scores on child cognitive assessment. Although there is minimal risk of LT4 treatment to keep TSH within the pregnancy-specific reference range, treatment of mild maternal thyroid hypofunction remains controversial, given the lack of clinical trials showing improved outcomes with LT4 treatment.

Follow-up of infants born to mothers with Graves' disease

INTRODUCTION

The prevalence of neonatal hyperthyroidism (HN) due to maternal Graves Disease (GD) ranges from 0.1 to 2.7%. It may occur in pregnant women with the following: active DG, after treatment with radioactive iodine, anti-thyroid or thyroidectomy or with a previous child with hyperthyroidism. The aim of our observational study was to evaluate the follow-up of infants born to mothers with GD at a Tertiary Hospital prior to the implementation of a follow-up protocol.

METHODS

This was a retrospective observational study using data from the medical records of mothers with a diagnosis of GD and their newborns from January 2013 until May 2018. Newborns were divided into two groups: high and low risk for NH according to maternal TRAb, third trimester treatment and signs of fetal hyperthyroidism.

RESULTS

We identified 31 newborns, 58% female; 87% high risk. In none of the newborns was umbilical cord blood collected. In the high risk group, 22% had thyroid function evaluation at day-1, one patient presented with hyperthyroidism and 82% were asymptomatic. Considering the cases with an insufficient blood sample for analysis, 9 consultations would have been spared. We found a significant delay in obtaining the high-risk group results which would have spared 10 appointments. A positive correlation was found between age at outpatient clinic discharge and the number of appointments and the maternal TRAb titer.

CONCLUSION

The correct surveillance of pregnancy and newborns with identification of those at high risk is essential to avoid unnecessary consultations and blood analyses that increase parental anxiety and hospital costs. Consequently, a multidisciplinary protocol was created to standardize the approach.

Thyroid Disease in Pregnancy: ACOG Practice Bulletin, Number 223

Both thyrotoxicosis and hypothyroidism are associated with adverse pregnancy outcomes. There also is concern about the effect of overt maternal thyroid disease on fetal development. In addition, medications that affect the maternal thyroid gland can cross the placenta and affect the fetal thyroid gland. This document reviews the thyroid-related pathophysiologic changes that occur during pregnancy and the effects of overt and subclinical maternal thyroid disease on maternal and fetal outcomes. This Practice Bulletin has been updated with information on the diagnosis and the management of thyroid disease in pregnant women and includes a new clinical algorithm on management of thyroid disease in pregnancy.

Fetal Physiologically Based Pharmacokinetic Models: Systems Information on the Growth and Composition of Fetal Organs

BACKGROUND

The growth of fetal organs is a dynamic process involving considerable changes in the anatomical and physiological parameters that can alter fetal exposure to xenobiotics in utero. Physiologically based pharmacokinetic models can be used to predict the fetal exposure as time-varying parameters can easily be incorporated.

OBJECTIVE

The objective of this study was to collate, analyse and integrate the available time-varying parameters needed for the physiologically based pharmacokinetic modelling of xenobiotic kinetics in a fetal population.

METHODS

We performed a comprehensive literature search on the physiological development of fetal organs. Data were carefully assessed, integrated and a meta-analysis was performed to establish growth trends with fetal age and weight. Algorithms and models were generated to describe the growth of these parameter values as functions of age and/or weight.

RESULTS

Fetal physiologically based pharmacokinetic parameters, including the size of the heart, liver, brain, kidneys, lungs, spleen, muscles, pancreas, skin, bones, adrenal and thyroid glands, thymus, gut and gonads were quantified as a function of fetal age and weight. Variability around the means of these parameters at different fetal ages was also reported. The growth of the investigated parameters was not consistent (with respect to direction and monotonicity).

CONCLUSION

Despite the limitations identified in the availability of some values, the data presented in this article provide a unique resource for age-dependent organ size and composition parameters needed for fetal physiologically based pharmacokinetic modelling. This will facilitate the application of physiologically based pharmacokinetic models during drug development and in the risk assessment of environmental chemicals and following maternally administered drugs or unintended exposure to environmental toxicants in this population.

Ultrasound Measurements of Fetal Thyroid: Reference Ranges from a Cohort of Low-Risk Pregnant Women

Background

Adequate thyroid function is essential for normal growth and development of the fetus. Sonographic recognition of alterations in fetal thyroid dimensions may be the first sign of thyroid dysfunction, permitting early diagnosis and intervention. The main goal of this study was to build curves with reference values for ultrasound measurements of the fetal thyroid from 14 to 40 weeks of gestation.

Methods

This is a prospective longitudinal study of 90 Brazilian pregnant women, complementary to a cohort multicentre study named “WHO multicentre study for the development of growth standards from fetal life to childhood: the fetal component.” Pregnant women without any pre-existing conditions that might affect fetal growth received antenatal care from the first trimester until childbirth, undergoing serial ultrasound evaluations of the fetus, including the thyroid. Longitudinal, anteroposterior, and transverse diameters of both thyroid lobes were measured in the fetus. Fetal thyroid lobe volume was also estimated. By quantile regression analysis, reference curves of measurements were fitted according to the gestational age.

Results

A reference standard of thyroid growth was defined during pregnancy by fitting curves of its measurements. Reference values for the 10^th, 50^th, and 90^th centiles of fetal thyroid measurements (longitudinal, anteroposterior, transverse diameters, and lobe volume) were defined, from 14 to 40 weeks of gestation.

Conclusion

We provided a reference curve of optimal thyroid development in a low-risk population that can be used as a standard of comparison to diagnose deviations from the norm. In addition, we demonstrated an alternative and simplified method for early recognition of thyroid morphological alterations by an individualized technique to evaluate the thyroid lobes.

Hyperthyroidism and Pregnancy

Clinical hyperthyroidism affects 0.1% to 0.4% of pregnancies. Gestational thyrotoxicosis is due to homology of the structure of TSH and HCG, which weakly stimulates the TSH receptor. Graves' disease (GD) most commonly causes clinically significant hyperthyroidism. Given concerns for teratogenicity from antithyroid drugs, these may be discontinued in low-risk GD patients. High-risk patients are treated with propylthiouracil in the first trimester then may transition to methimazole. Surgery is reserved for special circumstances; radioactive iodine is contraindicated. In late pregnancy, GD may remit; postpartum relapse is common. Measurement of serum thyrotropin receptor antibodies identifies pregnancies at-risk for fetal and neonatal hyperthyroidism.

Ultrasound Measurements of Thyroid Gland Volume at 36 Weeks' Corrected Gestational Age in Extremely Preterm Infants Born before 28 Weeks' Gestation

BACKGROUND

Thyroid ultrasound is a non-invasive imaging tool and provides good evaluation of thyroid anatomy, location, vascularisation, and echogenicity. The aim of this study was to assess thyroid function and thyroid volume in extremely preterm infants born before 28 weeks' gestation evaluated at 36 weeks' corrected gestational age (CGA) compared to term infants' normative data in the literature.

DESIGN

In this largest prospective UK study of extremely premature infants born at less than 28 weeks' gestation, thyroid volume measurement was assessed at 36 weeks' CGA. Fifty-five extremely preterm infants (28 males) who were born before 28 weeks' gestation were recruited to the study. All infants had ultrasound assessment of the thyroid gland at 36 weeks' CGA. We also prospectively measured thyroid stimulating hormone (TSH) and free thyroxine (FT4) in all infants at the time of recruitment (within 5 days of birth), at days 14, 21, and 28, and at 36 weeks' CGA.

RESULTS

The mean thyroid volume was measured at 0.57 mL (SD ±0.18). There was no association between mean thyroid volume and thyroid function (TSH or FT4). No associations were found between mean thyroid volume and gestation or birth weight in these infants.

CONCLUSIONS

Our findings provide a reference range with a mean thyroid volume of 0.57 mL (SD ±0.18) in this extremely preterm age group if less than 28 weeks' gestation. Thyroid volume at birth can vary from country to country due to variations in iodine intake as well as gestational age.

Comparative analysis of thyroid function parameters in pregnant women

The aim of the present study was to investigate the serum levels of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) during pregnancy and comparative analysis of serum markers levels in non-pregnant women and pregnant women. Pregnant women were divided into four groups according to their gestational age: 8-14, 15-20, 21-36 and ≥37 weeks. Non-pregnant women were divided into three groups according to their age: 20-40, 41-55 and 56-85 years, and women of reproductive age (20-40 years) as control, which match their age and body mass index with pregnant women. The levels of serum markers were measured by magnetic microparticle chemiluminescence immunoassay and compared among different gestational weeks or with the control. In pregnant women, from 8-14 to ≥37 weeks, FT3 and FT4 levels declined, and significant differences were identified between each group, except for FT4 at 21-36 weeks, when compared with ≥37 weeks. While TSH was increased and significant differences were identified between each group. Compared with the control group, the concentrations of FT3, FT4 and TSH were lower in pregnant women for all weeks except for TSH in ≥37 weeks. Reference intervals of FT3, FT4 and TSH in pregnant women are much lower than that of the control women. Pregnant women are likely to have lower thyroid hormone levels throughout pregnancy. The current reference intervals of thyroid hormones were not feasible for pregnant women and pregnancy-specific reference intervals should be established according to a local Chinese pregnant women database.

Fetal goitrous hypothyroidism treated by intra-amniotic levothyroxine administration: case report and review of the literature

BACKGROUND

Fetal goitrous hypothyroidism is mainly caused by maternal treatment of Graves' disease. Fetal goiter sometimes compresses the trachea and esophagus and may cause polyhydramnios, preterm labor, complications of labor and delivery, and neonatal respiratory disorder.

CASE PRESENTATION

We report a case of fetal goitrous hypothyroidism in which the mother had Graves' disease, which was treated with propylthiouracil. Intra-amniotic levothyroxine (L-T4) administration was performed, and the fetal goiter decreased in size. A female infant was delivered without goiter and complications. Thyroid function was within the normal range.

CONCLUSIONS

Previous reports on fetal goitrous hypothyroidism that was treated with intra-amniotic L-T4 showed that patients who had intra-amniotic L-T4 administration were likely to have a good outcome compared with patients who did not have L-T4. Thyroid function of the mother and fetus should be carefully monitored and treated appropriately.

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

BACKGROUND

Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2011, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid disease in women during pregnancy, preconception, and the postpartum period.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. The guideline task force had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy, and directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid disease in pregnant and postpartum women. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with these disorders.

Follow-up of newborns of mothers with Graves' disease

BACKGROUND

Overt neonatal Graves' disease is rare, but may be severe, even life threatening, with deleterious effects on neural development. The main objective of this study was to describe the course of thyrotropin (TSH) and free thyroxin (fT4) levels, as well as postnatal weight gain in relation to fT4 levels, in neonates born to women with Graves' disease without overt neonatal thyrotoxicosis. Such information is important to deduce the optimal schedule for evaluation.

METHODS

We conducted a retrospective chart review of neonates born to mothers with Graves' disease between January 2007 and December 2012. The records were reviewed for sex, gestational age, birth weight, maternal treatment during pregnancy, and maternal thyroid stimulating immunoglobulin (TSI) level. For each visit in the clinic, the data included growth parameters, presence of symptoms suspected for hyperthyroidism, blood test results (levels of TSH, fT4, and TSI), and treatment.

RESULTS

Ninety-six neonates were included in the study (49 males), with a total of 320 measurements of thyroid function tests (TSH and fT4). Four neonates (4%) had overt neonatal Graves' disease; one of them along with nine others were born preterm. In 77 (92.9%) of the remaining 83 neonates (the subclinical group), fT4 levels were above the 95th percentile on day 5. All had normal fT4 on day 15. A negative association was found between fT4 and weight gain during the first two weeks.

CONCLUSIONS

In this cohort, most neonates born to mothers with Graves' disease had a subclinical course with abnormal fT4 levels that peaked at day 5. After day 14, all measurements of fT4 returned to the normal range, although measurements of TSH remained suppressed for up to three months. Elevated fT4 was associated with poor weight gain.

Management of hyperthyroidism during pregnancy in Asia

Maternal hyperthyroidism in pregnancy is associated with adverse impacts on both mother and fetus. Recently, the American Thyroid Association and the Endocrine Society have published guidelines for the management of thyroid diseases in pregnancy. We aimed to disclose the impact of these guidelines in current practices of Asian members of the Asia-Oceania Thyroid Association (AOTA) regarding the management of hyperthyroidism in pregnancy. Completed questionnaire survey, based on clinical case scenarios, was collected from 321 Asian physician members of AOTA from 21 Asian countries in 2013. For a woman with Graves' disease planning pregnancy, 92% of clinicians favored antithyroid treatment, 52% with propylthiouracil (PTU) while 40% preferred methimazole (MMI). For a pregnant woman with newly diagnosed overt hyperthyroidism, nearly all responders initiated PTU treatment. To monitor dosage of antithyroid drugs, approximately 73% of responders used TSH and free T4 (FT4) levels without free T3 (FT3) (53%) or with FT3 (20%). Majority of responders targeted achieving low serum TSH with FT4 (or total T4) in the upper end of the normal range. For management of gestational thyrotoxicosis, 40% chose to follow up and 52% treated patients with PTU. Although timing of TSH receptor antibodies measurement in pregnant hyperthyroid patients was variable, 53% of responders would check it at least once during pregnancy. Nearly 80% of responders do not treat subclinical hyperthyroidism in pregnancy. Therefore, despite wide variations in the management of hyperthyroidism during pregnancy in Asia, majority of Asian physicians practice within the recommendations of major professional societies.

Fetal and neonatal thyrotoxicosis

Fetal thyrotoxicosis is a rare disease occurring in 1 out of 70 pregnancies with Grave's disease or in 1 out of 4000-50,000 deliveries. The mortality is 12-20%, usually from heart failure, but other complications are tracheal compression, infections and thrombocytopenia. It results from transfer of thyroid stimulating immunoglobulins from mother to fetus through the placenta. This transplacental transfer begins around 20(th) week of pregnancy and reaches its maximum by 30(th) week. These autoantibodies bind to the fetal thyroid stimulating hormone (TSH) receptors and increase the secretion of the thyroid hormones. The mother has an active autoimmune thyroid disease or has been treated for it in the past. She may be absolutely euthyroid due to past treatment by drugs, surgery or radioiodine ablation, but still have active TSH receptor stimulating autoantibodies, which can cause fetal thyrotoxicosis. The other features of this disease are fetal tachycardia, fetal goiter and history of spontaneous abortions and findings of goiter, ascites, craniosyntosis, fetal growth retardation, maceration and hydrops at fetal autopsy. If untreated, this disease can result in intrauterine death. The treatment for this disease consists of giving carbimazole to the mother, which is transferred through the placenta to the fetus. The dose of carbimazole is titrated with the fetal heart rate. If the mother becomes hypothyroid due to carbimazole, thyroxine is added taking advantage of the fact that very little of thyroxine is transferred across the placenta. Neonatal thyrotoxicosis patients are very sick and require emergency treatment. The goal of the treatment is to normalize thyroid functions as quickly as possible, to avoid iatrogenic hypothyroidism while providing management and supportive therapy for the infant's specific signs and symptoms.

Size and location of thyroid gland in the fetal period

PURPOSE

The present study's purpose was to examine the size and location of the thyroid gland using anatomic dissection methods on fetal cadavers.

METHODS

This study was performed on 200 spontaneously aborted human fetuses (100 males and 100 females) aged between 9 and 40 weeks of gestation. Fetuses without any external and internal pathology or anomaly were included in this study. Fetuses were divided into four groups based on gestational ages as follows: first group 9-12 weeks (first trimester), second group 13-25 weeks (second trimester), third group 26-37 weeks (third trimester) and fourth group 38-40 weeks (full term). The fetuses were also grouped into monthly cohorts as follows: 9-12 weeks, 3rd month; 13-16 weeks, 4th month; 17-20 weeks, 5th month; 21-24 weeks, 6th month; 25-28 weeks, 7th month; 29-32 weeks, 8th month; 33-36 weeks, 9th month; and 37-40 weeks, 10th month. The anterior necks of fetuses were dissected and the thyroid glands exposed. Vertebral and laryngeal levels and the dimensions (width, length, thickness and weight) of the fetal thyroid glands were determined by anatomical dissection methods. The dimensions and ratios of the fetal thyroid gland (weight/fetal body weight) were evaluated.

RESULTS

The mean values and standard deviations of all parameters by gestational weeks, months, and trimesters were calculated. It was found that all parameters increased with gestational age. No significant differences were observed between genders in all parameters (P > 0.05). There were no significant differences between the right and the left sides for parameters of the thyroid glands. The levels of the superior poles of the thyroid lobes were located at the cervical (C) C1-C3 vertebral bodies. The levels of the inferior poles of the thyroid lobes were located at C4-C5 vertebral bodies. The levels of the superior poles of thyroid lobes were located between the upper ½ and lower ½ of the thyroid cartilage or cricoid cartilage. The levels of the inferior poles of the thyroid lobes were located between the second and sixth tracheal rings. The distance between the superior poles of the thyroid gland and the hyoid bone increased throughout the fetal period. The dimensions of fetal thyroid glands increased with gestational age. The ratio between thyroid gland weights and fetal body weights was unchanged during the fetal period.

CONCLUSIONS

We believe that the results obtained from this study will be useful in monitoring thyroid glands in the intrauterine period as well as recognizing early diagnosis and treatment of thyroid anomalies. It will also contribute to future studies in obstetrics, perinatology, and fetopathology.

Antithyroid drug-induced fetal goitrous hypothyroidism

Maternal overtreatment with antithyroid drugs can induce fetal goitrous hypothyroidism. This condition can have a critical effect on pregnancy outcome, as well as on fetal growth and neurological development. The purpose of this Review is to clarify if and how fetal goitrous hypothyroidism can be prevented, and how to react when prevention has failed. Understanding the importance of pregnancy-related changes in maternal thyroid status when treating a pregnant woman is crucial to preventing fetal goitrous hypothyroidism. Maternal levels of free T(4) are the most consistent indication of maternal and fetal thyroid status. In patients with fetal goitrous hypothyroidism, intra-amniotic levothyroxine injections improve fetal outcome. The best way to avoid maternal overtreatment with antithyroid drugs is to monitor closely the maternal thyroid status, especially estimates of free T(4) levels.

Graves' disease in two pregnancies complicated by fetal goitrous hypothyroidism: successful in utero treatment with levothyroxine

BACKGROUND

Treatment of Graves' disease during pregnancy with antithyroid drugs (ATDs) poses a risk of inducing hypothyroidism and, thus, development of a goiter to the fetus.

PATIENT FINDINGS

We report two patients referred to our department after discovery of a fetal goiter by ultrasound examination in the second trimester of pregnancy. The women receiving 400 mg/day propylthiouracil and 10 mg/day thiamizole, respectively, had thyrotropin and total thyroxine values within the normal reference range but a lowered free thyroxine level. Fetal blood sampling by cordocentesis revealed severe fetal hypothyroidism as the cause of goiter development. Reduction of maternal ATD dose and injection of levothyroxine intra-amniotically quickly reduced the goiter size, and both babies were born euthyroid and without goiters.

SUMMARY

Two pregnant women with Graves' disease were overtreated with ATDs inducing iatrogenic goiter in the fetuses. Successful treatment with intra-amniotic levothyroxine injections rendered the babies euthyroid and nongoitrous at birth.

CONCLUSIONS

Correct interpretation of thyroid function tests during pregnancy in general--and during ATD therapy of Graves' disease in particular--is difficult. Awareness of pregnancy-related changes in maternal thyroid status, and a close teamwork among endocrinologists, obstetricians, and experts in fetal medicine, is pivotal in ensuring normal growth and development of the unborn child of these patients.

Use of 3-dimensional sonography for prenatal evaluation and follow-up of fetal goitrous hypothyroidism

OBJECTIVE

Fetal goitrous hypothyroidism is a rare and potentially lethal condition. Consequently, its early diagnosis and treatment improve prognosis. Thyroid hormone measurement in either fetal serum or amniotic fluid implies important risks. Here we present a fetal goiter and the follow-up procedure, both done by the traditional method and by using 3-dimensional power Doppler (3DPD) imaging and virtual organ computer-aided analysis (VOCAL).

METHODS

A single well-documented case of fetal goiter was followed weekly from 22 weeks until delivery. Amniocentesis for thyrotropin (TSH) and free thyroxine (T(4)) measurement as well as levothyroxine injections were performed at every control. In addition to amniocentesis, every control involved a sonographic evaluation, which included standard measurements of the gland and the capture of volume image sets in gray scale and 3DPD. Volume calculation of the gland was done using VOCAL software. Vascularization of the gland was evaluated by the vascularization index (VI) included in the software.

RESULTS

With treatment, TSH levels decreased progressively until normalization. Free T(4) levels increased toward the end of gestation. Sonographic measurements of the gland volume to estimated fetal weight ratio decreased across treatment as levels of TSH did. The VI clearly depicted the vascular regression of the goiter, decreasing throughout treatment in a consistent way until 24 hours before delivery.

CONCLUSIONS

Gray scale and 3DPD evaluations of the thyroid gland have been validated under similar circumstances and might be reliable complements to the invasive methods used in the management of this fetal condition.

Pregnancy outcome, thyroid dysfunction and fetal goitre after in utero exposure to propylthiouracil: a controlled cohort study

AIMS

Propylthiouracil (PTU) is presently considered to be the treatment of choice for hyperthyroidism in pregnancy. It is known to cross the human placenta, and therefore may affect the fetus. The major aims of this study were to evaluate the rate of major anomalies and to report the rate of fetal goitre, accompanied by hypothyroidism, in fetuses/ newborns of mothers after in utero exposure to PTU.

METHODS

Prospective observational controlled cohort study of PTU-exposed pregnancies of women counselled by the Israeli Teratology Information Service between the years 1994 and 2004 compared with women exposed to nonteratogens.

RESULTS

We followed up 115 PTU-exposed pregnancies and 1141 controls. The rate of major anomalies was comparable between the groups [PTU 1/80 (1.3%), control 34/1066 (3.2%), P= 0.507]. Hypothyroidism was found in 9.5% of fetuses/neonates (56.8% of whom with goitre). Hyperthyroidism, possibly resulting from maternal disease, was found in 10.3%. Goitres prenatally diagnosed by ultrasound were successfully treated in utero by maternal dose adjustment. In most cases neonatal thyroid functions normalized during the first month of life without any treatment. Median neonatal birth weight was lower [PTU 3145 g (2655-3537) vs. control 3300 g (2968-3600), P= 0.018].

CONCLUSIONS

PTU does not seem to be a major human teratogen. However, it could cause fetal/neonatal hypothyroidism with or without goitre. Fetal thyroid size monitoring and neonatal thyroid function tests are important for appropriate prevention and treatment.

Fetal heart rate tracing patterns associated with congenital hypothyroidism

OBJECTIVE

This study was undertaken to determine fetal heart rate (FHR) tracing patterns associated with congenital hypothyroidism.

STUDY DESIGN

FHR patterns of 59 women whose babies were diagnosed with congenital hypothyroidism were retrospectively compared with tracings of 78 of their siblings. Tracings were interpreted during the first stage of labor. Multivariable analysis was used to control for confounders.

RESULTS

Neonates with congenital hypothyroidism had significantly higher rates of reduced variability in FHR tracing patterns as compared with those without congenital hypothyroidism (49.2% vs 3.8%; odds ratio, 24.1; 95% confidence interval, 6.8-85.3; P < .001). No significant differences were noted between the groups regarding decelerations or baseline abnormalities. The significant association between congenital hypothyroidism and reduced variability persisted after controlling for confounders such as treatment with pethidine, MgSO4, and gestational age (odds ratio, 14.1; 95% confidence interval, 1.1-190.7; P = .046).

CONCLUSION

Congenital hypothyroidism is significantly and independently associated with reduced variability in FHR tracing patterns.

Thyroid disorders of neonates born to mothers with Graves' disease

Maternal hyperthyroidism implies the risk of thyroid abnormalities in the newborn. We describe retrospectively the clinical presentation, treatment and follow up of 28 children born of hyperthyroid mothers. Patients were subdivided as follows: Group A (neonatal hyperthyroidism) (n=9): born from eight hyperthyroid mothers and one thyroidectomized mother. Children born from untreated mothers consulted between 1 and 7 days of life, while those born from treated mothers consulted between 8 and 17 days. Eight needed treatment. All remitted completely. Group B (primary hypothyroidism) (n=14): born from treated mothers, detected by neonatal screening. Eleven had transient hypothyroidism and three needed treatment. Group C (hypothalamic-pituitary hypothyroidism) (n=5): born from uncontrolled hyperthyroid mothers and found during follow up (age 9-28 days). The infants were treated with thyroid hormone, and recovered before 8 months of life. Every child born from a mother with autoimmune thyroid disease needs paediatric endocrinological assessment for detection of possible thyroid disorders.

Use of ultrasound to distinguish between fetal hyperthyroidism and hypothyroidism on discovery of a goiter

OBJECTIVES

To determine whether sonography can be used to distinguish hyperthyroidism from hypothyroidism in pregnancies with fetal goiter.

METHODS

This was a retrospective study of 39 cases of fetal goiter. The majority of the mothers had Graves' disease. Fetuses were scanned for the existence of a hypertrophic thyroid gland (goiter) beginning at 22 gestational weeks. Once a goiter was diagnosed, different echographic features were analyzed and the effect of chosen treatment on fetal thyroid development was monitored.

RESULTS

On color Doppler, 68.8% of hypothyroid goiters had a peripheral vascular pattern vs. 20% in cases of fetal hyperthyroidism (P = 0.0574). No hypothyroid goiter presented central vascularization whereas half the hyperthyroid goiters did (P = 0.0013). Fetal tachycardia was a good indicator of hyperthyroidism (57.1% v.s 6.3%; P = 0.0055). Delayed bone maturation was seen in hypothyroid goiters (46.9% vs. 0%; P = 0.0307), while advanced bone maturity was specific to hyperthyroid goiters (85.7% vs. 0%; P < 0.0001). Lastly, an increase in fetal movement was observed in cases of fetal hypothyroidism (43.8% vs. 0%; P = 0.0364).

CONCLUSION

Based on the color Doppler pattern of goiter, fetal heart rate, bone maturation and fetal mobility, we established an ultrasound score to predict fetal thyroid function in cases of fetal goiter.

Management of Graves' hyperthyroidism in pregnancy: focus on both maternal and foetal thyroid function, and caution against surgical thyroidectomy in pregnancy

Graves' disease is a common autoimmune disorder in women in fertile ages. The hyperthyroidism is caused by generation of TSH-receptor activating antibodies. In pregnancy both the antibodies and the antithyroid medication given to the mother pass the placenta and affect the foetal thyroid gland. Thyroid function should be controlled not only in the mother with Graves' hyperthyroidism but also in her foetus.The review includes two cases illustrating some of the problems in managing Graves' disease in pregnancy. Major threats to optimal foetal thyroid function are inadequate or over aggressive antithyroid drug therapy of the mother. It should be taken into account that antithyroid drugs tend to block the foetal thyroid function more effectively than the maternal thyroid function, and that levothyroxin (L-T(4)) given to the mother will have only a limited effect in the foetus. Surgical thyroidectomy of patients with Graves' hyperthyroidism does not lead to immediate remission of the autoimmune abnormality, and the combination thyroidectomy+withdrawal of antithyroid medication+L-T(4) replacement of the mother involves a high risk of foetal hyperthyroidism. Conclusion Antithyroid drug therapy of pregnant women with Graves' hyperthyroidism should be balanced to control both maternal and foetal thyroid function. Surgical thyroidectomy of a pregnant woman with active disease may lead to isolated foetal hyperthyroidism.

Successful intrauterine therapy for fetal goitrous hypothyroidism during late gestation

We experienced a case of fetal goitrous hypothyroidism in an infant delivered by a 33-year-old woman receiving 300 mg/day of propylthiouracil (PTU) for hyperthyroidism due to Graves' disease. A large fetal goiter (maximum diameter, 60 mm) was detected by magnetic resonance imaging (MRI) at 36 weeks of gestation. Initial fetal blood sampling revealed hypothyroidism with a serum thyroid-stimulating hormone (TSH) of 99 microIU/mL, free triiodothyronine (T(3)) of 1.97 pg/mL, and free thyroxine (T(4)) of 0.29 ng/dL. Consequently, a diagnosis of fetal goitrous hypothyroidism due to transplacental passage of maternal PTU was made. To reduce the risk of perinatal complications, 300 microg of levothyroxine sodium (L-T(4)) was administered into the maternal amniotic fluid twice between 37 and 38 weeks of gestation. Subsequent fetal MRI showed that the size of goiter had decreased. At 38 weeks and 5 days of gestation, a 3042-g male infant was born by cesarean section. There were no severe complications at delivery, although mild tachypnea was observed and the infant's thyroid gland was slightly enlarged. He was treated with L-T(4) for two weeks. At present, his growth and neurological development are normal. This case indicates that intrauterine therapy by the intraamniotic administration of L-T(4) can be effective in treating fetal goitrous hypothyroidism even during late gestation.

Therapy Insight: management of Graves' disease during pregnancy

The diagnosis of Graves' disease in pregnancy can be complex because of normal gravid physiologic changes in thyroid hormone metabolism. Mothers with active Graves' disease should be treated with antithyroid drugs, which impact both maternal and fetal thyroid function. Optimally, the lowest possible dose should be used to maintain maternal free thyroxine levels at or just above the upper limit of the normal nonpregnant reference range. Fetal thyroid function depends on the balance between the transplacental passage of thyroid-stimulating maternal antibodies and thyroid-inhibiting antithyroid drugs. Elevated levels of serum maternal anti-TSH-receptor antibodies early in the third trimester are a risk factor for fetal hyperthyroidism and should prompt evaluation of the fetal thyroid by ultrasound, even in women with previously ablated Graves' disease. Maternal antithyroid medication can be modulated to treat fetal hyperthyroidism. Serum TSH and either total or free thyroxine levels should be measured in fetal cord blood at delivery in women with active Graves' disease, and those with a history of (131)I-mediated thyroid ablation or thyroidectomy who have anti-TSH-receptor antibodies. Neonatal thyrotoxicosis can occur in the first few days of life after clearance of maternal antithyroid drug, and can last for several months, until maternal antibodies are also cleared.

Thyroid disease in pregnancy

Thyroid testing during pregnancy should be performed on symptomatic women or those with a personal history of thyroid disease. Overt hypothyroidism complicates up to 3 of 1,000 pregnancies and is characterized by nonspecific signs or symptoms that are easily confused with complaints common to pregnancy itself. Physiologic changes in serum thyroid-stimulating hormone (TSH) and free thyroxine (T(4)) related to pregnancy also confound the diagnosis of hypothyroidism during pregnancy. If the TSH is abnormal, then evaluation of free T(4) is recommended. The diagnosis of overt hypothyroidism is established by an elevated TSH and a low free T(4). The goal of treatment with levothyroxine is to return TSH to the normal range. Overt hyperthyroidism complicates approximately 2 of 1,000 pregnancies. Clinical features of hyperthyroidism can also be confused with those typical of pregnancy. Clinical hyperthyroidism is confirmed by a low TSH and elevation in free T(4) concentration. The goal of treatment with thioamide drugs is to maintain free T(4) in the upper normal range using the lowest possible dosage. Postpartum thyroiditis requiring thyroxine replacement has been reported in 2% to 5% of women. Most women will return to the euthyroid state within 12 months.

Goitrous congenital hypothyroidism in a twin pregnancy causing respiratory obstruction at birth: implications for management

We report a twin pregnancy complicated by fetal goitrous hypothyroidism secondary to dyshormonogenesis caused by thyroglobulin deficiency. Antenatal treatment with intra-amniotic thyroxine was considered but not performed, given the late gestational age at diagnosis and the multiple nature of the pregnancy. Both twins developed airway obstruction at delivery, requiring intubation and ventilation. We review the literature and describe the practical issues relating to the antenatal assessment and perinatal management of fetal goitre.

Comparison of ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs

OBJECTIVE

To determine ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs and evaluate the relationships of thyroid gland size and volume with body weight and body surface area (BSA).

ANIMALS

72 dogs of small (6 Toy and 6 Miniature Poodles), medium (12 Beagles), and large breeds (12 Akitas and 36 Golden Retrievers).

PROCEDURE

Each dog's thyroid gland was examined ultrasonographically with a 10- to 5-MHz multifrequency linear-array transducer. Size, shape, echogenicity, and homogeneity of thyroid lobes were evaluated on longitudinal and transverse images. Thyroid lobe volume was estimated by use of the equation for an ellipsoid (pi/6 [length x height x width]).

RESULTS

Thyroid lobes appeared fusiform or elliptical on longitudinal images and triangular or round to oval on transverse images. In most dogs, thyroid lobes were hyperechoic or isoechoic, compared with surrounding musculature, and had a homogeneous echogenic pattern. Mean length, width, height, and volume of thyroid lobes were significantly greater in Akitas and Golden Retrievers, compared with findings in Beagles or Poodles; mean length, width, and height were significantly greater in Beagles, compared with findings in Poodles. Total thyroid gland volume correlated with body weight (r = 0.73) and BSA (r = 0.74).

CONCLUSIONS AND CLINICAL RELEVANCE

Among the dog breeds examined ultrasonographically, thyroid lobe size and volume were more variable than shape, echogenicity, and homogeneity. The correlation of thyroid gland volume with BSA suggests that size of the dog, rather than breed, should be considered when assessing thyroid glands ultrasonographically.

[Correct procedure in the presence of a fetal goiter associated with hypothyroidism. Observations from three cases]

Fetal goiter is a rare occurrence of which neonatal consequences are not always predictable. Concerning three cases of goiters associated with hypothyroidism discovered in utero, the authors describe the way to take care of in this bad codified situation. They insist upon the major role of ultrasound for goiter diagnosis and its impacts and for control of treatment efficiency. They also discuss intra amniotic L-Thyroxine injection and insist upon the necessity to obtain quick and definite thyroid evaluation after birth before decision to abstain from neonatal therapy.

Thyroid disorders in pregnancy

PURPOSE OF REVIEW

There is now increasing understanding of the association between not only overt, but also subclinical, thyroid disorders and dysfunction with adverse reproductive outcome. In particular, hypothyroidism and thyroid autoimmunity disorders have been shown to have both short- and long-term consequences on mother and child. An updated review is merited to revise many of the traditional views on thyroid disorders in pregnancy.

RECENT FINDINGS

Thyroid disorders constitute the commonest group of pre-gestational endocrine disorders found in pregnant women. In mothers taking antithyroid medications, breastfeeding is considered safe. The relatively high prevalence of hypothyroidism, especially subclinical hypothyroidism, the significance of screening and treatment, and the roles of iodine insufficiency and thyroid antibodies on the outcome of pregnancy and long-term neurological development of the offspring have been documented. In hypothyroid women, the dose of thyroxine replacement often needs to be adjusted from as early as the first trimester to maintain an adequate circulating thyroxine concentration.

SUMMARY

Apart from overt hyperthyroidism and hypothyroidism diagnosed before and during pregnancy, biochemical abnormalities or evidence of thyroid autoimmunity in clinically euthyroid women can affect both obstetric outcome and long-term neurological development of the offspring. Screening for thyroid function and autoimmunity, and timely and appropriate treatment, will improve pregnancy outcome. The thyroid function of infants born to mothers with thyroid disorders should also be assessed as serial monitoring and treatment may be necessary.

Management of Graves' disease during pregnancy: the key role of fetal thyroid gland monitoring

BACKGROUND

Fetuses from mothers with Graves' disease may experience hypothyroidism or hyperthyroidism due to transplacental transfer of antithyroid drugs (ATD) or anti-TSH receptor antibodies, respectively. Little is known about the fetal consequences. Early diagnosis is essential to successful management. We investigated a new approach to the fetal diagnosis of thyroid dysfunction and validated the usefulness of fetal thyroid ultrasonograms.

METHODS

Seventy-two mothers with past or present Graves' disease and their fetuses were monitored monthly from 22 wk gestation. Fetal thyroid size and Doppler signals, and fetal bone maturation were determined on ultrasonograms, and thyroid function was evaluated at birth. Thyroid function and ATD dosage were monitored in the mothers.

RESULTS

The 31 fetuses whose mothers were anti-TSH receptor antibody negative and took no ATDs during late pregnancy had normal test results. Of the 41 other fetuses, 30 had normal test results at 32 wk, 29 were euthyroid at birth, and one had moderate hypothyroidism on cord blood tests. In the remaining 11 fetuses, goiter was visualized by ultrasonography at 32 wk, and fetal thyroid dysfunction was diagnosed and treated; there was one death, in a late referral, and 10 good outcomes with normal or slightly altered thyroid function at birth. The sensitivity and specificity of fetal thyroid ultrasound at 32 wk for the diagnosis of clinically relevant fetal thyroid dysfunction were 92 and 100%, respectively.

CONCLUSION

In pregnant women with past or current Graves' disease, ultrasonography of the fetal thyroid gland by an experienced ultrasonographer is an excellent diagnostic tool. This tool in conjunction with close teamwork among internists, endocrinologists, obstetricians, echographists, and pediatricians can ensure normal fetal thyroid function.

Obstetric complications due to autoantibodies

Autoimmune diseases are most common and most active in young women; it is therefore not uncommon for obstetricians and physicians to encounter pregnant women with these conditions, and knowledge of the potential maternal, foetal and neonatal complications is essential for good clinical management. The most common maternal autoimmune endocrine conditions in pregnancy are insulin-dependent diabetes mellitus and thyroid disease. Other relatively common non-endocrine autoimmune conditions include systemic lupus erythematosus and anti-phospholipid syndrome. Much rarer autoimmune conditions include autoimmune thrombocytopenia, rheumatoid arthritis, myasthenia gravis and Addison's disease. In this chapter, we discuss autoimmune endocrine conditions and briefly mention some non-endocrine conditions of particular importance.