Successful intrauterine therapy for fetal goitrous hypothyroidism during late gestation

Effect of Addition of Thyroxine in the Treatment of Graves' Disease: A Systematic Review

Graves' disease is the most common cause of hyperthyroidism. Antithyroid drugs, radioiodine ablation, and surgery are the main treatments. Research has demonstrated that adding thyroxine to antithyroid therapy can improve the remission rate, and many similar studies have been conducted subsequently. The purpose of this systematic review was to investigate whether adding thyroxine to various treatments for Graves' disease has a clinical benefit in remission/relapse rate, stable thyroid function, occurrence of Graves' ophthalmopathy, etc. A total of 27 studies were included, and the risk of research bias was moderate to high. We discuss the role of thyroxine both in pharmacological and non-pharmacological therapeutic regimens. Overall, the available evidence does not support the indiscriminate addition of thyroxine to various treatments for Graves' disease, especially in combination with oral antithyroid drugs. Further clinical studies are required to explore the indications of thyroxine addition in the treatment of Graves' disease.

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.

Graves' disease complicated by fetal goitrous hypothyroidism treated with intra-amniotic administration of levothyroxine

Fetal goitrous hypothyroidism is a rare entity and is caused mainly by maternal treatment of Graves' disease (GD). We report a case of a 22-year-old woman referred at 12 weeks of gestation due to hyperthyroidism subsequent to recently diagnosed GD. She started treatment with propylthiouracil and, at 21 weeks of gestation, fetal goitre was detected. A cordocentesis confirmed the diagnosis of fetal goitrous hypothyroidism, and intra-amniotic administration of levothyroxine (LT4) was performed and repeated through the pregnancy due to maintenance of fetal goitre. The pregnancy proceeded without further complications and a healthy female infant was born at 37 weeks of gestation, with visible goitre and thyroid function within the normal range at birth. Although there is no consensus on the optimal dose, the number of injections and the interval between them, intra-amniotic LT4 administration is recommended once fetal goitrous hypothyroidism is suspected, in order to prevent long-term complications of fetal hypothyroidism.

Current knowledge about the in utero and peripartum management of fetal goiter associated with maternal Graves' disease

Maternal Graves’ disease is the most common cause of fetal goiter. Fetal goiter can cause complications attributable either to the physical effects of the goiter itself or to thyroid dysfunction, which can be life-threatening and cause neurological impairment. Determining whether a goiter is caused by fetal hyperthyroidism or hypothyroidism is the main clinical problem, and in utero evaluations and management are essential. Ultrasonography combined with color Doppler and magnetic resonance imaging are helpful for the initial diagnosis and monitoring, but these imaging techniques have a limited ability to discriminate between fetal hyperthyroidism and hypothyroidism. To determine the fetal thyroid status, fetal blood sampling using cordocentesis is reliable but hazardous, and the indications must be considered carefully. Amniocentesis is an easier and safer alternative, but the correlations between the amniotic fluid and fetal serum thyroid hormone levels remain unclear. If a fetal goiter is accompanied by hypothyroidism, administering thyroid hormone intra-amniotically may be effective and relatively safe. However, the wide variety of approaches to treatment exemplifies the lack of guidelines, and no systematic studies have been conducted to date. Therefore, intrauterine treatment should be reserved for selected patients at a high risk of complications. Moreover, when intrauterine treatment fails and a fetal goiter can cause airway obstruction, intrapartum management, such as ex utero intrapartum treatment, may be required; however, reports describing the use of this procedure for fetal goiter are limited. This review summarizes the current knowledge about fetal goiter associated with maternal Graves’ disease and evaluates the most significant new findings regarding its in utero and peripartum management.

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.

Sequential Amniotic Fluid Thyroid Hormone Changes Correlate with Goiter Shrinkage following in utero Thyroxine Therapy

Several isolated reports of fetal goiter treatment have shown limited generalizability of approaches and provide no real guidance for optimal timing, dosages, and treatment strategies. Graves' disease accounts for >60% of these cases. Maternal treatments of hyperthyroidism include antithyroid medications such as methimazole and more commonly propylthiouracil (PTU). Here, our management of a patient with a fetal thyroid goiter from maternal exposure to PTU diagnosed at 23.6 weeks' gestation and the management of other cases allow us propose a general strategy for treatment. Intrauterine therapy with 200 and then 400 μg of levothyroxine (3 weeks apart) showed an 85% reduction in fetal thyroid goiter volume. We collected amniotic fluid samples at the time of treatments and assayed thyroid hormones and associated antibodies which closely reflected the changes in thyroid goiter mass volume. Our observations suggest a weekly or biweekly therapeutic intervention schedule. Utilizing both goiter size as well as a novel approach in using amniotic fluid hormone levels to monitor therapy efficacy might improve the quality of treatments. Only with a standardized approach and collection of amniotic fluid thyroid panels do we have the opportunity to develop the database required to determine the number and timing of treatments needed.

Effects of maternal exposure to thiamazole on behavioral development in infant cynomolgus monkeys

Thiamazole, an anti-hyperthyroidism agent, was administered orally to pregnant cynomolgus monkeys at doses of 2.0 and 3.5 mg/kg per day from GD 120 to GD 150 to investigate effects on behavioral development of their infants. Swelling of the throat region due to enlargement of the thyroid glands was observed at birth in thiamazole-treated infants, and it returned to normal around postnatal day (PND) 30. At necropsy of infants at 12 months of age, thyroidal weight in the thiamazole groups was increased. This finding suggested the likelihood that administration of thiamazole to maternal animals during the late gestational period induced thyroid goiter in fetal/infant monkeys through placental transfer of thiamazole. No clear changes were noted in thyroid histopathology or serum thyroid hormone levels in maternal animals or infants, but goiter formation might have been indicative of exposure to high thyroid stimulating hormone (TSH) and low T3 or T4 in utero from maternal treatment with thiamazole. Age-related changes were observed in the control in behavioral development tests, while infants at 3.5 mg/kg showed no age-related decrease in contact behavior and no increase in exploratory activity on PND 90 or PND 170. In addition, the number of eye contacts between PND 210 and PND 240 was less frequent. This indicated that maternal exposure to thiamazole induced mental retardation-like behaviors in infants. Thiamazole may directly inhibit thyroid hormone synthesis in the fetus by placental transfer. From these results, it was speculated that oral administration of thiamazole to maternal animals during the late gestational period induced retardation of behavioral development in their infants.

Fetal and neonatal goiter in cynomolgus monkeys following administration of the antithyroid drug thiamazole at high doses to dams during pregnancy

To evaluate morphologic alterations in the thyroid gland in the second generation in cynomolgus monkeys, pregnant dams were exposed to high doses of thiamazole. In Experiment A, dams received thiamazole intragastrically via a nasogastric catheter from gestation day (GD) 50 to GD 150 or on the day before delivery. Initially, the dose level was 20 mg/kg/day (10 mg/kg twice daily); however, the dose level was subsequently decreased to 5 mg/kg/day (2.5 mg/kg twice daily), since deteriorated general conditions were observed in two dams. Six out of seven neonates died on the day of birth. The cause of neonatal death was tracheal compression and suffocation from goiter. The transplacental exposure to thiamazole affected the fetal thyroid glands and induced goiter in all neonates. The surviving neonate was necropsied 767 days after discontinuation of thiamazole exposure and showed reversibility of the induced changes. In Experiment B, dams were intragastrically administered thiamazole at 5 mg/kg/day (2.5 mg/kg twice daily) for treatment periods from GDs 51 to 70, 71 to 90, 91 to 110, 111 to 130 and 131 to 150. All fetuses showed enlarged thyroid glands but were viable. Histopathologically, hypertrophy and/or hyperplastic appearance of the follicular epithelium of the thyroid gland was observed at the end of each treatment period. The most active appearance of the follicular epithelium, consisting of crowded pedunculated structure, was demonstrated at end of the treatment period from GD 131 to 150. This is the first report on the morphology of fetal and neonatal goiter in the cynomolgus monkey.

Prenatal pharmacotherapy for fetal anomalies: a 2011 update

Fetal therapy can be defined as any prenatal treatment administered to the mother with the primary indication to improve perinatal or long-term outcomes for the fetus or newborn. This review provides an update of the pharmacological therapies that are solely directed at the fetus with anomalies and outlines a future transcriptomic approach. Fetal anomalies targeted with prenatal pharmacotherapy are a heterogeneous group of structural, endocrine, and metabolic conditions, including congenital cystic adenomatoid malformation (CCAM), congenital adrenal hyperplasia, congenital heart block, fetal tachyarrhythmias, inborn errors of metabolism, fetal thyroid disorders, and polyhydramnios. To date, the majority of pharmacotherapies for fetal anomalies have been evaluated only in retrospective, uncontrolled studies. The way forward will be with an evidence-based approach to prenatal pharmacological interventions.

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.

Intrauterine diagnosis and management of fetal goiter: a case report

Fetal goiter can be the result of maternal hyperthyroidism treated with antithyroid drugs. Polyhydramnios may be the presenting symptom and can be diagnosed prenatally by sonography. We report a case of fetal goiter diagnosed at 30 weeks of gestation and fetal hypothyroidism confirmed by cordocentesis. Intra-amniotic levothyroxine was administered. Onset of preterm labor could not be prevented. The risks and benefits of intrauterine treatment of fetal goitrous hypothyroidism are discussed.

Experience with intraamniotic thyroxine treatment in nonimmune fetal goitrous hypothyroidism in 12 cases

CONTEXT

Nonimmune fetal goitrous hypothyroidism is a rare condition that can induce obstetrical and/or neonatal complications and neurodevelopmental impairments such as those still seen in some patients with congenital hypothyroidism. Prenatal treatment to prevent these adverse outcomes is appealing, but experience is limited and the risk to benefit ratio controversial.

OBJECTIVE

The objective of the study was to evaluate the feasibility, safety, and effectiveness of intrauterine l-thyroxine treatment in a large cohort with nonimmune fetal goitrous hypothyroidism.

DESIGN

This was a retrospective study of 12 prenatally treated fetuses diagnosed between 1991 and 2005 in France.

METHODS

During pregnancy, goiter size and thyroid hormone levels were compared before and after prenatal treatment. At birth, clinical, laboratory, and ultrasound data were evaluated.

RESULTS

Prenatal treatment varied widely in terms of l-thyroxine dosage (200-800 microg/injection), number of injections (one to six), and frequency (every 1-4 wk). No adverse events were recorded. During pregnancy, thyroid size decreased in eight of nine cases and amniotic-fluid TSH levels decreased in the six investigated cases, returning to normal in four. However, at birth, all babies had hypothyroidism, indicating that intraamniotic TSH levels did not reliably reflect fetal thyroid function.

CONCLUSION

Our data confirm the feasibility and safety of intraamniotic l-thyroxine treatment for nonimmune fetal goitrous hypothyroidism. Although goiter size reduction is usually obtained, thyroid hormone status remains deficient at birth. Amniocentesis seems inadequate for monitoring fetal thyroid function. Further studies are needed to determine the optimal management of this disorder.

Treating fetal thyroid and adrenal disorders through the mother

Advances in imaging techniques and in molecular diagnosis have enabled the identification in the fetus of disorders of thyroid and adrenal function that can potentially be treated in utero through the mother. In women with Graves disease, the rare instances of autoimmune fetal hyperthyroidism can generally be treated in a noninvasive way by optimizing treatment of the mother. For fetal hypothyroidism with goiter leading to hydramnios, repeated intra-amniotic injections of thyroxine have been reported to decrease the size of the fetal thyroid, but experience is limited and the risk of premature labor is raised. In women who have previously borne a child with severe congenital adrenal hyperplasia, attempts to prevent virilization of the external genitalia of further affected female fetuses involves treatment with high doses of dexamethasone from week 7 of gestation to term, which includes the crucial period of organogenesis. Only one of every eight fetuses treated will, however, benefit from this therapy, meaning that seven are unnecessarily exposed to this potentially harmful agent. In this article, we review the rationale and evidence for efficacy of these approaches, and discuss their potential adverse effects as well as the ethical problems that they raise.