Hyperthyroidism during pregnancy

The Pharmacotherapy of Thyroid Storm

A review of thyrotoxic storm is presented. Included are causes, symptomatology, and mortality rates. Special emphasis is placed on the strong correlation between adrenergic blockade and success rates in treating thyrotoxic storm. Pharmacotherapy of the acute storm patient is discussed in detail with respect to agents that (1) decrease production of thyroid hormones; (2) block release of preformed thyroid hormones from the gland; (3) blunt the effects of excess thyroid hormones on the various target organs (e.g., CNS and heart); and (4) serve to decrease the metabolic strain on all organ systems caused by thyrotoxic storm.

Effectiveness of preoperative plasmapheresis in a pregnancy complicated by hyperthyroidism and anti-thyroid drug-associated angioedema

Hyperthyroidism is not a rare entity in pregnancy and 85% of these cases attributed to Graves' disease (GD). There is no therapeutic modality for GD considered as totally safe in pregnancy. Fetal and neonatal risks of maternal hyperthyroid disease are related to the hyperthyroidism itself and/or to the medical treatment of the disease. There are no data supporting an association between congenital anomalies in the fetus and propylthiouracil (PTU). Hepatotoxicity, cytopenias--especially agranulocytosis and quite rarely, angioedema, may be seen as side effects of PTU. In this case report, we examine an instance of Graves' hyperthyroidism diagnosed during pregnancy. In this case, a serious side effect during anti-thyroid drug usage was encountered, eventually resulting in surgery in the second trimester. This intervention was assisted by the use of plasmapheresis to obtain rapid normalization of serum thyroid hormone levels.

Propylthiouracil is teratogenic in murine embryos

Background

Hyperthyroidism during pregnancy is treated with the antithyroid drugs (ATD) propylthiouracil (PTU) and methimazole (MMI). PTU currently is recommended as the drug of choice during early pregnancy. Yet, despite widespread ATD use in pregnancy, formal studies of ATD teratogenic effects have not been performed.

Methods

We examined the teratogenic effects of PTU and MMI during embryogenesis in mice. To span different periods of embryogenesis, dams were treated with compounds or vehicle daily from embryonic day (E) 7.5 to 9.5 or from E3.5 to E7.5. Embryos were examined for gross malformations at E10.5 or E18.5 followed by histological and micro-CT analysis. Influences of PTU on gene expression levels were examined by RNA microarray analysis.

Results

When dams were treated from E7.5 to E9.5 with PTU, neural tube and cardiac abnormalities were observed at E10.5. Cranial neural tube defects were significantly more common among the PTU-exposed embryos than those exposed to MMI or vehicle. Blood in the pericardial sac, which is a feature indicative of abnormal cardiac function and/or abnormal vasculature, was observed more frequently in PTU-treated than MMI-treated or vehicle-treated embryos. Following PTU treatment, a total of 134 differentially expressed genes were identified. Disrupted genetic pathways were those associated with cytoskeleton remodeling and keratin filaments. At E 18.5, no gross malformations were evident in either ATD group, but the number of viable PTU embryos per dam at E18.5 was significantly lower from those at E10.5, indicating loss of malformed embryos. These data show that PTU exposure during embryogenesis is associated with delayed neural tube closure and cardiac abnormalities. In contrast, we did not observe structural or cardiac defects associated with MMI exposure except at the higher dose. We find that PTU exposure during embryogenesis is associated with fetal loss. These observations suggest that PTU has teratogenic potential.

Bismuth iodoform paraffin paste: a review

Introduction:

This article reviews the literature pertaining to bismuth iodoform paraffin paste.

Overview:

Bismuth iodoform paraffin paste is used in most otolaryngology departments on a daily basis. Questions about its properties are common in postgraduate otolaryngology examinations. This article reviews bismuth iodoform paraffin paste's current and historical usage, constituents, properties, side effects, and radiographic properties, and its alternatives in otological and rhinological practice.

Aplasia cutis congenita in surviving co-twin after propylthiouracil exposure in utero

AIM

Aplasia cutis congenita (ACC) has been observed after fetal exposure to the antithyroid drug methimazole (MMI), but not reported after propylthiouracil (PTU), the current antithyroid drug of choice during pregnancy. This occurrence has implications for patient information and causal research.

CASE REPORT

We describe a surviving term co-twin to a mother with hyperthyroidism exposed to PTU from conception to 34 weeks of gestation presenting with ACC at birth.

DISCUSSION

The association between PTU exposure and ACC is clinically relevant and allows speculation on the etiology. A similar mechanism to the classical MMI-induced ACC is postulated, unless a vascular etiology suggested by a vanishing twin or maternal hyperthyroidism itself is causal. Coincidence of PTU exposure and ACC seems unlikely.

CONCLUSION

ACC in a newborn after PTU exposure during pregnancy hitherto observed only after MMI strongly encourages further reports of similar cases that may remain clinically underdiagnosed or unreported. Such confirmation could have significant implications for maternal treatment of hyperthyroidism, common in women of childbearing age.

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.

Graves hyperthyroidism and pregnancy: a clinical update

OBJECTIVE

To provide a clinical update on Graves' hyperthyroidism and pregnancy with a focus on treatment with antithyroid drugs.

METHODS

We searched the English-language literature for studies published between 1929 and 2009 related to management of hyperthyroidism in pregnancy. In this review, we discuss differential diagnosis of hyperthyroidism, management, importance of early diagnosis, and importance of achieving proper control to avoid maternal and fetal complications.

RESULTS

Diagnosing hyperthyroidism during pregnancy can be challenging because many of the signs and symptoms are similar to normal physiologic changes that occur in pregnancy. Patients with Graves disease require prompt treatment with antithyroid drugs and should undergo frequent monitoring for signs of fetal and maternal hyperthyroidism and hypothyroidism. Rates of maternal and perinatal complications are directly related to control of hyperthyroidism in the mother. Thyroid receptor antibodies should be assessed in all women with hyperthyroidism to help predict and reduce the risk of fetal or neonatal hyperthyroidism or hypothyroidism. The maternal thyroxine level should be kept in the upper third of the reference range or just above normal, using the lowest possible antithyroid drug dosage. Hyperthyroidism may recur in the postpartum period as Graves disease or postpartum thyroiditis; thus, it is prudent to evaluate thyroid function 6 weeks after delivery. Preconception counseling, a multidisciplinary approach to care, and patient education regarding potential maternal and fetal complications that can occur with different types of treatment are important.

CONCLUSION

Preconception counseling and a multifaceted approach to care by the endocrinologist and the obstetric team are imperative for a successful pregnancy in women with Graves hyperthyroidism.

Hyperthyroidism in pregnancy

Graves' disease may complicate the course of pregnancy; pregnancy on the other hand may alter the natural course of the disease. It is imperative for women of childbearing age affected by the disease to be informed about the potential maternal and fetal problems if the condition is not properly managed. Preconception control in women with diabetes has resulted in a dramatic decrease in the number of perinatal complications. The same approach should be encouraged for women with thyroid diseases. Ideally, the women suffering from hyperthyroidism or any other thyroid disease should be metabolically compensated at time of conception-the need for contraception until the disease is controlled should be openly discussed. A multidisciplinary approach by a health care team is of paramount importance during pregnancy, with the involvement of the obstetrician, perinatologist, endocrinologist, neonatologist, pediatrician and anesthesiologist. In many situations the assistance of social workers, nutritionists, and other health care professionals may be needed. The future mother and her family should be aware of the potential complications for both mother and her offspring if proper management guidelines are not carefully followed.

Fetal hydrops, associated with maternal propylthiouracil exposure, reversed by intrauterine therapy

Thyroid hormone is essential for fetal neurological development. Among other etiologies, fetal hypothyroidism may be caused by maternal exposure to antithyroid drugs (ATDs). The most common presentation of fetal hypothyroidism is fetal goiter, which can cause dystocia, in addition to airway obstruction in the neonate. Intra-amniotic treatment with levothyroxine normalizes fetal thyroid status and reduces goiter size. We present a case of fetal hypothyroidism diagnosed in a patient who was treated with propylthiouracil (PTU) for Grave's disease. The fetus had marked hydrops fetalis and a large goiter. In addition, anal stenosis, vesicovaginal fistula, bilateral pyelectasia and polydactyly were diagnosed in the neonate. Intra-amniotic treatment with levothyroxine resulted in a regression of the hydrops and a reduction in the goiter size. A euthyroid, non-edematous, non-goitrous neonate was delivered. At the age of 27 months the child's psychomotor development was normal. The present case indicates that hydrops fetalis may be an unusual manifestation of fetal hypothyroidism, caused by intrauterine exposure to maternal antithyroid drugs (ATDs), and that it may be resolved by treatment with intra-amniotic levothyroxine.

Hyperthyroidism in pregnancy

The prevalence of hyperthyroidism in pregnancy is about 0.2%. The most common cause is Graves' disease. Maternal, fetal, and neonatal morbidity and mortality may be reduced to a minimum with careful attention to the clinical symptoms and interpretation of thyroid tests. Ideally, hyperthyroid women should be rendered euthyroid before considering conception. The incidence of maternal and neonatal morbidity is significantly higher in those patients whose hyperthyroidism is not medically controlled. Even the incidence of thyroid storm is high in women who are under poor medical supervision in the presence of a medical or obstetric complication. Maternal morbidity includes a higher incidence of toxemia, premature delivery, placenta abruptio, congestive heart failure, and thyroid crisis. In some series, anemia and infections were also reported. Neonatal morbidity includes SGA neonates, intrauterine growth retardation, LBW infants, and prematurity. Fetal goiter and transient neonatal hypothyroidism is occasionally reported in infants of mothers who have been overtreated with ATD. Propylthiouracil and MMI are equally effective in controlling the disease. In most patients, symptoms improved and thyroid tests returned to normal in 3-8 weeks after initiation of therapy. Resistance to ATD is extremely rare, most cases are caused by patient poor compliance. Surgery for the treatment of hyperthyroidism is reserved for the unusual patient who is allergic to both ATD; to those who have large goiters; to those who require large doses of ATD; or to those patients who poorly comply. Fetal and neonatal hyperthyroidism can be predicted in the majority of cases by the previous maternal medical and obstetric history and by the proper interpretation of thyroid tests. Finally, hyperthyroidism may recur in the postpartum period.

Diagnosis and management of Graves' disease in pregnancy

Most of the hyperthyroidism seen in association with pregnancy is Graves' disease. The best treatment is prevention. For most patients there is an opportunity to treat the hyperthyroidism decisively with radioiodine or surgery before the patient becomes pregnant. Pregnancy complicated by hyperthyroidism is often a consequence of the conscious decision to treat hyperthyroidism in women in the childbearing years with antithyroid drugs. Propylthiouracil (PTU) is the preferred treatment for hyperthyroidism in pregnancy, but it does cross the placenta and can induce fetal goiter, with mental and physical retardation. Hence, the lowest possible PTU dose should be used. One should aim for high normal or slightly elevated thyroid function in the mother. Patients should be followed at 3-week intervals if progress is satisfactory, more often otherwise. Thyroid function should be monitored by the free T4 assay. PTU dosage should be reduced progressively in anticipation of the customary steady amelioration in the hyperthyroidism that occurs in later stages of pregnancy. Since pregnant hyperthyroid patients are sometimes irresponsible and continue PTU without supervision, PTU prescriptions should be limited to the amount required for the time until the next scheduled visit. For about one third of patients, PTU can be discontinued in the second half of the pregnancy. After the pregnancy is terminated, persistent or recurrent hyperthyroidism should be treated definitively to prevent another episode of pregnancy complicated by hyperthyroidism.

On the possible effects of homeostatic shifts in human embryonic development

Possible etiological factors of congenital malformations as well as of human trisomies are considered in the framework of the repressor hypothesis. In this approach gene expression is envisaged from the point of view of the functional variations of the total activation energy for normal gene expression in homeostatic equilibrium. We restrict our attention to variations of the total activation energy under the effect of temperature gradients. We discuss the evidence that hyperthermia may be an etiological factor for trisomies in humans.

Graves' disease during pregnancy

Presented are two case studies which investigate the adverse effects of Graves' disease in pregnant women. Particular attention has been paid to the therapeutic regimen and its implications for the maternal, fetal and neonatal well-being. The first case study illustrates that Graves' disease complicating pregnancy can be treated by bed rest and careful observation of mother and fetus. The first pregnancy of our second case study confirms these results. Her second pregnancy, in which the symptoms of Graves' disease were far more severe, illustrates that it is possible to treat fetal hyperthyroidism by treating the pregnant mother with antithyroid drugs. If great care is taken to avoid overtreatment of the fetus, the treatment with antithyroid drugs is superior to surgical treatment, since surgery completely neglects the problem of fetal hyperthyroidism.

Hyperthyroidism complicating pregnancy: results of treatment by antithyroid drugs in 77 pregnancies

Seventy-seven pregnancies (79 infants) complicated by hyperthyroidism were seen at three Dublin Maternity Hospitals during a 25 year period. Hyperthyroidism was diagnosed following conception in 14 pregnancies. Treatment was with carbimazole alone in 73 pregnancies, in a usual dose of 5 to 10 mg daily. The total fetal loss was 15.2 per cent with a perinatal loss of 5.1 per cent. The perinatal loss in patients treated with carbimazole alone was 4.1 per cent (excluding one death due to congenital malformation). Four infants (5.1 per cent) had goitre and 57 (85.1 per cent) of the surviving infants were above the 25th centile for gestational age. Spontaneous premature labour occurred in 7 pregnancies (9.1 per cent). There was a relative excess of infants with a birth weight less than the 25th centile, of neonatal goitre and premature labour after pregnancy in which treatment was started following conception. Hyperthyroidism complicating pregnancy can be treated effectively with antithyroid drugs given alone and in the minimal effective dose.

Fetal hypothyroidism complicating medical treatment of thyrotoxicosis in pregnancy

Two women with thyrotoxicosis were treated with antithyroid drugs during pregnancy. One women had inadvertently received a therapeutic dose of radioiodine at 21 weeks gestation and the other suffered from severe thyrotoxicosis with a serum LATS level of 1850%. In both patients, the serum triiodothyronine was maintained above 500 ng/dl by the concurrent oral administration of this hormone. Despite this precaution, cord serum thyrotrophin levels were markedly elevated and both infants showed clinical signs of hypothyroidism at birth. This experience indicates that triiodothyronine does not prevent fetal hypothyroidism when given to the mother in pharmacological amounts.