The systematic screening and management of hypothyroidism and hyperthyroidism during pregnancy

Altogether, thyroid function abnormalities during pregnancy can affect up to 10% of all women. The high prevalence of both hypo- and hyperthyroidism, the obstetrical repercussions associated with thyroid dysfunction in the mothers, as well as the potential role of maternal thyroid dysfunction as an influence on fetal development constitute solid arguments for a further increase of our knowledge of the pathophysiological processes underlying the alterations of thyroid function related to the pregnant state. In this review, the focus will be on the most clinically relevant aspects associated with hypothyroidism [autoimmune thyroid disorders (AITDs), subfertility, risk of miscarriage, risk of hypothyroidism in women with AITD and treatment of hypothyroid women] and with hyperthyroidism (clinical presentations during pregnancy, Graves' disease and its management, fetal hyperthyroidism in women with antithyroid-stimulating hormone receptor antibodies and gestational transient thyrotoxicosis associated with human chorionic gonadotropin stimulation of the maternal thyroid gland). I also propose a global strategy for the systematic screening of hypo- and hyperthyroidism in the pregnant state.

[Evolution of diagnostic and therapeutic criteria in Graves' disease in Spain. Comparison of the results of 2 surveys in 1987 and 1995]

BACKGROUND

To assess the new diagnostic and therapeutic trends for hyperthyroidism due to Graves' disease in Spain and the differences with respect to a previous study performed in 1987.

METHODS

A questionnaire about a typical clinical case of hyperthyroidism due to Graves' disease and 10 variations to it, in which different diagnostic and therapeutic options are exposed. These questionnaires were mailed to 70 Spanish units of endocrinology during 1995, and 51 participated finally in the study. The results are compared with those obtained in Spain with a similar study in 1987.

RESULTS

Thyrotropin (98%) and free thyroxine (88%) were the most used tests for diagnosis of Graves' disease, with a significant decrease (p < 0.001) in the use of total T4 and total T3 in comparison with the results of the questionnaire performed in 1987. The measurement of antibodies against thyrotropin receptor (TSH-R-Ab) was the most frequently used immune marker for the diagnosis (78%), with significant differences (p < 0.001) with respect to questionnaire in 1987. The use of anti-thyroperoxidase antibodies (anti-TPO-Ab) (36%) in diagnosis of this disease, significantly increased (p < 0.05) with respect to 1987. Antithyroid drugs were the most frequent initial treatment (98%) with significant differences (p < 0.001) in use of radioiodine (24%) as treatment of choice in elderly patients respect to 1987. Surgery was mainly used for large-size goiters (33%) and radioiodine for recurrences after medical (61%) or surgical (80%) treatment. Antithyroid drugs were the most frequent treatment for children and for recurrences during gestation.

CONCLUSIONS

In Spain, the measurements of TSH, FT4 and TSH-R-Ab are the main diagnostic test of hyperthyroidism. Antithyroid drugs are still the treatment of choice in typical case of hyperthyroidism due to Graves' disease, in recurrences during gestation and children. Surgery is only used for large goiters and radioiodine is the treatment of choice in recurrences after medical or surgical treatment.

Thyroid hyperfunction during pregnancy

The present report focuses on the two main causes of hyperthyroidism observed in the pregnant state: Graves' disease (GD) and gestational transient thyrotoxicosis. Together, the prevalence of hyperthyroidism may represent 3% to 4% of all pregnancies, and therefore constitutes an important clinical issue. Concerning GD, the variable presentations of the disease (women under treatment, in remission, or considered cured) and specific alterations occurring in pregnancy are discussed: changes in thyrotropin (TSH) receptor antibody titers, the risk of fetal and neonatal thyrotoxicosis, the outcome of pregnancy in relation to the control of hyperthyroidism, and the treatment of active GD during and after pregnancy with antithyroid drugs. Gestational transient thyrotoxicosis is associated with a direct stimulation of the maternal thyroid gland by human chorionic gonadotropin (hCG), and has been shown to be directly related to both the amplitude and duration of peak hCG values. The syndrome is usually transient, observed at the end of the first trimester, and is frequently associated with emesis. Finally, we propose a global strategy for the systematic screening of hyperthyroidism during pregnancy, based on an algorithm that allows for the diagnosis of both autoimmune and nonautoimmune forms of hyperthyroidism in the pregnant state.

The thyrotrophic role of human chorionic gonadotrophin (hCG) in the early stages of twin (versus single) pregnancies

OBJECTIVE

Human chorionic gonadotrophin (hCG) is known to possess thyroid-stimulating activity. The aim of the present study was to assess the role of hCG in stimulating the maternal thyroid gland in the early stages of normal gestation.

STUDY DESIGN

Thirty euthyroid healthy women were investigated prospectively. In each, conception had been assisted by in vitro fertilization techniques, which allowed for the precise determination of gestational age. Women were subdivided into single (n = 17) and twin (n = 13) pregnancies. Serum intact hCG and its free alpha and beta subunits, TSH and free T4 concentrations were measured at 6, 8, 9, 10, 11, 15, 19, 22 and 32 weeks.

RESULTS

In twin pregnancies compared with single pregnancies, peak hCG concentrations (9-11 weeks) were significantly higher (mean +/- SE 171,000 +/- 12,500 vs 65,500 +/- 7600 U/l; P < 0.001), and also much more prolonged. Human CG concentrations above 75,000 U/l lasted for less than 1 week in single, compared with up to 6 weeks in twin pregnancies. Free beta-hCG subunit concentrations paralleled those of intact hCG in both groups. The ratios of free beta-hCG subunit/total hCG were similar in single and twin pregnancies, and did not vary with gestation time. Concerning thyroid function, twin pregnancy was more frequently associated with a lowering of TSH, which was also more profound than in single pregnancies. Furthermore, while free T4 levels remained normal in single pregnancies, they were transiently supranormal (up to 52 pmol/l) in four twin pregnancies.

CONCLUSION

In twin pregnancies the placenta produces larger amounts of hCG for a prolonged period of time than in single pregnancies. Both the amplitude and duration of hCG production (i.e. the global exposure of the thyroid gland to hCG) are responsible for increased thyroidal stimulation, leading more frequently to increased free T4 and suppressed TSH levels. The results emphasize the role of hCG in stimulating maternal thyroid function in the first trimester of pregnancy. Even though the production of a variant hCG molecule with potent thyrotrophic activity cannot be excluded, this hypothesis is not required to explain the data. Clinicians should be aware of the frequent occurrence of significant but transient biochemical hyperthyroidism associated with hCG stimulation in the early stages of gestation, particularly in twin pregnancies.

[Thyroid nodule and cancer in pregnant women]

Most thyroid nodules discovered during pregnancy are benign. In this article, we propose a pragmatic attitude for the diagnosis and treatment of such nodules, insisting particularly on the importance of thyroid echography and fine needle aspiration. For women who have successfully been treated for thyroid cancer before pregnancy, we discuss the adaptation of thyroxine substitution when they become pregnant, the obstetrical and fetal risks (spontaneous miscarriage, fetal abnormalities of the thyroid gland and others), and also potential later risks for the child, in relation with previous radioactive iodine administration to the mother. Finally, we evoke more difficult questions, such as the rare instances in which thyroid cancer is discovered during pregnancy, pregnancy occurring during the months immediately following radioiodine treatment, and exceptional cases where therapeutic radioiodine was inadvertently given during pregnancy.

[Thyroid changes in the pregnant woman]

In Belgium the iodine intake is restricted and even marginally insufficient. During pregnancy, the insufficient iodine supply is associated with chronic stimulation of the thyroid gland, leading to the development of gestational goiters and to an increased risk of foetal goitrogenicity. Also, approximately one third of pregnant women exhibit relative hypothyroxinemia. Moreover, women who present chronic autoimmune thyroiditis and in whom thyroid function is normal at the onset of pregnancy carry a significant risk of developing thyroid insufficiency during gestation. In conclusion, healthy pregnant women should be given the benefit of iodine supplementation, both during pregnancy and breastfeeding. This will allow them to maintain a well adapted thyroid function, prevent goitrogenicity, and ensure adequate foetal hormone production. For women with autoimmune thyroiditis, thyroid function should be closely monitored during pregnancy and the slightest indication of thyroid insufficiency should prompt the administration of thyroid hormone substitution.

[Reevaluation of antithyroid drug therapy in Graves disease]

Though antithyroid medical therapy has been used for several decades in the medical treatment of hyperthyroidism, only recently has attention been drawn towards prospective controlled trials concerning the effect in relation to dosage as well as the dosage related to side effects. A review is given in relation to recent investigations on treatment strategies in various parts of the world as well as the most frequently used strategies in Europe. Special attention is given to treatment principles in relation to pregnancy, children and adolescents as well as patients with eye symptoms. Antithyroid drug therapy of hyperthyroidism is a frequent and successful treatment strategy in Europe. Globally, there are still large discrepancies in the treatment strategies, related rather to conventions than to a rational attitude.

A randomized trial for the treatment of mild iodine deficiency during pregnancy: maternal and neonatal effects

One hundred and eighty euthyroid pregnant women were selected at the end of the first trimester of gestation on the basis of biochemical criteria of excessive thyroid stimulation, defined as supranormal serum thyroglobulin (TG > 20 micrograms/L) associated with a low normal free T4 index (< 1.23) and/or an increased T3/T4 ratio (> 25 x 10(-3)). Women were randomized in a double blind protocol into three groups and treated until term with a placebo, 100 micrograms potassium iodide (KI)/day, or 100 micrograms iodide plus 100 micrograms L-T4/day. Parameters of thyroid function, urinary iodine excretion, and thyroid volume were monitored sequentially. Neonatal thyroid parameters, including thyroid volume by echography, were also assessed in the newborns from mothers of the three groups. In women receiving a placebo, the indices of excessive thyroid stimulation worsened as gestation progressed, with low free T4 levels, markedly increased serum TG and T3/T4 ratio. Serum TSH doubled, on the average, and was supranormal in 20% of the cases at term. Urinary iodine excretion levels were low, around 30 micrograms/L at term. The thyroid volume increased, on the average, by 30%, and 16% of the women developed a goiter, confirming the goitrogenic stimulus associated with pregnancy. Moreover, the newborns of these mothers had significantly larger thyroid volumes at birth as well as elevated serum TG levels. In both groups of women receiving an active treatment, the alterations in thyroid function associated with pregnancy were markedly improved. The increase in serum TSH was almost suppressed, serum TG decreased significantly, and changes in thyroid volume were minimized (group receiving KI) or almost suppressed (group receiving KI combined with L-T4). Moreover, in the newborns of the mothers in the two groups receiving an active treatment, serum TG was significantly lower, and thyroid volume at birth was normal. The effects of therapy were clearly more rapid and more marked in the group receiving a combination of T4 and KI than in the women receiving KI alone. The differences could be partly attributed to the slightly higher amount of iodine received by women in the combined treatment. However, the main benefits of the combined treatment were almost certainly attributable to the hormonal effects of the addition of L-T4. Furthermore, the study demonstrated that the administration of T4 did not hamper the beneficial effect of iodine supplementation. In conclusion, the present work emphasizes the potential risk of goitrogenic stimulation in both mother and newborn in the presence of mild iodine deficiency.(ABSTRACT TRUNCATED AT 400 WORDS)

Risk of subclinical hypothyroidism in pregnant women with asymptomatic autoimmune thyroid disorders

A prospective study was undertaken in 87 healthy pregnant women with thyroid antibodies and normal thyroid function at initial presentation [asymptomatic autoimmune thyroid disorders (AITD)]. The aims of the study were to assess whether women with AITD constitute a group at risk of developing subclinical hypothyroidism during pregnancy, and whether a mild thyroid function impairment may be associated with obstetrical repercussions. The women investigated were selected among a cohort of 1660 consecutive pregnancies on the basis of 1) no previous history of thyroid disease, 2) euthyroidism at initial presentation, and 3) positive thyroglobulin antibodies and/or thyroid peroxidase antibodies (TPO-Ab). Women with AITD had a basal TSH value significantly higher, albeit still normal, in the first trimester (1.6 vs. 0.9 mU/L; P < 0.001) than that in women with healthy pregnancies used as controls. Despite a 60% average reduction in TPO-Ab titers during gestation, serum TSH remained higher in women with AITD than in controls throughout gestation: at delivery, 40% of the cases had serum TSH levels above 3 mU/L, and 16% had serum TSH levels above 4 mU/L. A TRH test carried out in the days after parturition showed an exaggerated response in 50% of the cases. Furthermore, free T4 concentrations were in the range of hypothyroid values in 42% of the women. Obstetrical repercussions were observed, namely increased rates of spontaneous miscarriage and premature deliveries. In conclusion, women with asymptomatic AITD who are euthyroid in early pregnancy carry a significant risk of developing hypothyroidism progressively during gestation, despite a marked reduction in antibody titers. Hypothyroidism results from the reduced ability of the gland to adjust to the changes in thyroidal economy associated with pregnancy. At the individual level, progression to subclinical hypothyroidism was broadly predictable on the basis of serum TSH levels and TPO-Ab titers in the first trimester. Hence, these parameters provide useful markers to identify women who carry a higher risk, allowing for a close monitoring of thyroid function during pregnancy and the administration of L-T4 in specific cases. Taken together with the known incidences of postpartum thyroiditis and hypothyroidism in women with AITD, the present observations in our opinion justify systematic screening of thyroid autoimmunity during pregnancy.

Total amounts of circulating human chorionic gonadotrophin alpha and beta subunits can be assessed throughout human pregnancy using immunoradiometric assays calibrated with the unaltered and thermally dissociated heterodimer

The aim of the present study was to determine the variations in the balance between total (free plus combined) circulating alpha and beta subunits of human chorionic gonadotrophin (hCG) throughout human pregnancy. The equivalence between the International Units (IU) of hCG (IRP 75/537) and those assigned to the alpha (IRP 75/569) and beta (IRP 75/551) free subunits was experimentally determined by using intact and thermally dissociated hCG. Heat exposure (2 min at 100 degrees C) of hCG preparations resulted in a complete dissociation of hCG into free, soluble and intact alpha and beta subunits. The hCG and alpha and beta subunit contents of unaltered and heated hCG preparations were assessed by specific immunoradiometric assays. The amount of immunoreactive subunits dissociated by heat from hCG could then be evaluated on a molar basis. Circulating hCG and its free alpha and beta subunits were immunoassayed in 836 blood samples collected from healthy pregnant women at different gestational ages. After conversion of hCG and its subunits into a common IU system, the gestational profiles of the total amounts (free plus combined) of alpha- and beta hCG subunits increased together and peaked at 9-10 weeks of gestation. Thereafter, total alpha and beta subunits decreased and subsequently remained stable until term. The decline in total alpha hCG subunit was less marked than that of total beta hCG subunit. The alpha- to beta hCG ratio was equimolar until 10 weeks of gestation when it increased almost fourfold until term (P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Serum levels of intact human chorionic gonadotropin (HCG) and its free alpha and beta subunits, in relation to maternal thyroid stimulation during normal pregnancy

The main objective of the present study was to present additional evidence of the potentially important thyrotropic role of hCG to regulate the maternal thyroid gland during normal pregnancy. Sequential determinations (first and last trimesters) of intact hCG, free alpha and beta-hCG subunits concentrations (using monoclonal IRMAs), and assessment of parameters of thyroid function and thyroid volume were carried out in 62 pregnant women who exhibited during the first trimester of gestation low TSH levels (< or = 0.20 mU/L), and compared to 276 pregnant women with normal TSH levels. The prevalence of having low serum TSH represented 18% of all pregnancies, with almost one half of cases who transiently had undetectable TSH levels. Lowering of TSH was associated with high hCG levels, and occurred primarily during the first trimester. About 10% of women with low TSH presented transient gestational thyrotoxicosis, frequently associated with vomiting. In comparison to control subjects, women with a suppressed serum TSH had significantly and markedly higher intact hCG and free beta-hCG subunit concentrations. The results suggest that TSH reduction may result from a relative oversecretion of both intact hCG and free beta-hCG subunits, compatible with three hypotheses: a) transient overexpression of the beta-hCG gene, leading to enhanced production of hCG heterodimer; b) increased glycosylation of circulating hCG, with in turn a prolonged half life; c) larger syncytiotrophoblast mass with increased hCG production.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of eye muscle antibody measurements to monitor response to plasmapheresis in patients with thyroid-associated ophthalmopathy

We have measured eye muscle antibodies, in immunoblotting, in the serum from five patients with severe ophthalmopathy associated with Graves' hyperthyroidism who underwent plasmapheresis, correlating their levels with clinical features of the eye disorder and response to treatment. Blood taken before each plasma exchange was tested in SDS-polyacrylamide gel electrophoresis and Western blotting for antibodies reactive with pig eye muscle membrane (PEMM) antigens and in a 51Cr release assay for antibodies which are cytotoxic to human eye muscle cells in antibody-dependent cell-mediated cytotoxicity (ADCC). Antibodies reactive with a 64 kDa PEMM antigen were detected in three patients who had eye disease of less than six months duration, but not in the two with more chronic disease. Antibodies against a 95 kDa PEMM antigen were detected in one patient in whom anti-64 kDa antibodies were also demonstrated. All five patients showed significant improvement in their eye disease following plasmapheresis exchange and titres of the anti-64 kDa protein antibody decreased in the three patients with detectable levels before treatment. TSH receptor stimulating antibodies were detected in all five patients before treatment, falling during plasmapheresis in four and becoming undetectable in three by the end of treatment. There was no close correlation between levels of TSH receptor antibodies and titres of anti-64 kDa protein antibodies although both tended to fall during and following plasmapheresis. ADCC tests were negative in all five patients before plasmapheresis but, surprisingly, transiently positive in three following treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithyroid antibodies underlying thyroid abnormalities and miscarriage or pregnancy induced hypertension

OBJECTIVE

To assess whether asymptomatic abnormalities, including thyroid auto-antibodies, were associated with an abnormal miscarriage rate or a poor obstetric outcome.

DESIGN

Prospective study of thyroid auto-antibodies and thyroid function in an unselected obstetric population.

SETTING

Saint-Pierrie Hospital, Brussels, Belgium.

SUBJECTS

Seven hundred and thirty consecutive pregnant women attending the antenatal clinic.

MAIN OUTCOME MEASURES

Miscarriage and pregnancy induced hypertension.

RESULTS

Elevated antithyroperoxidase (TPO-Ab) and antithyroglobulin (TG-Ab) antibody titres are associated with an increased miscarriage rate. Also, asymptomatic thyroid abnormalities, mainly abnormal echo-structure but not antithyroid antibodies, are associated with pregnancy induced hypertension.

CONCLUSION

The presence of thyroid auto-antibodies during pregnancy constitutes a marker of increased risk of miscarriage and poor obstetric prognosis.

Maternal thyroid function in pregnancy

In healthy pregnant women, the regulation of thyroid function depends upon several factors. Three factors act independently to increase thyroid hormone requirements: 1) the marked increase in the binding capacity of serum due to high TBG levels; 2) the direct stimulation of the thyroid by human chorionic gonadotropin, acting as a thyrotropic hormone; and 3) the increase in placental deiodinating activity, which may contribute to modify thyroid hormone metabolism. These stimulatory events result in a physiological adaptation of the maternal thyroid gland to pregnancy, as long as the availability of iodine for the thyroidal "machinery" remains sufficient. Our studies were performed in an area where the iodine intake is precisely at the lower limit of the needs for healthy non pregnant adult subjects (less than 100 micrograms/day). In these conditions, decreased iodine availability during gestation leads to relative iodine deficiency and hence, pregnancy constitutes a "challenge" for the thyroid gland. It was shown that excessive thyroidal stimulation occurred in as much as one third of pregnancies in Brussels, accompanied by relative hypothyroxinemia, marked elevation in serum TG levels and goitrogenesis. About 10% of women had developed a goiter at parturition, which was only partially reversible during the postpartum period. A randomized prospective trial was then undertaken in euthyroid pregnant women who were below 16 weeks of gestation at initial presentation and who fulfilled biochemical criteria of excessive thyroidal stimulation (high molar T3/T4 ratio, low normal free T4 index, elevated serum TG). Thyroid function and volume were monitored sequentially during gestation.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid function parameters and TSH-receptor antibodies in healthy subjects and Graves' disease patients: a sequential study before, during and after pregnancy

The changes in thyroid function and in TSH receptor antibody titers were analyzed in a prospective sequential study before, during and after pregnancy in a group of 15 healthy women and 45 patients with Graves' disease. Twenty-five patients with Graves' disease were untreated before pregnancy (Group A) and twenty treated with carbimazole throughout pregnancy (Group B). In healthy pregnant women serum FT4 levels were slightly but significantly elevated early in pregnancy (p < 0.05) and lower during the third trimester (p < 0.01), compared to pregestational values (although within the reference range of nonpregnant subjects). During postpartum, serum FT4 reverted to values similar to those found before pregnancy. Serum TSH levels showed a slight increment during gestation with a significant decrease (p < 0.01) in the early postpartum period. There was a significant increase in serum thyroglobulin (Tg) during the first trimester (p < 0.01); Tg levels remaining markedly elevated throughout gestation. After delivery, Tg progressively decreased, but were still above normal, six months later in 27% of subjects. TSH-receptor antibody titers were normal but tended to decrease during late gestation; a significant rebound was observed in late postpartum, even though most individual values remained in the normal range. When we compared "active" and "remission" Graves' disease patients, the concentration of FT4 was significantly higher in group B ("active") than in group A ("remission" (p < 0.01) during early gestation. Serum Tg was also significantly higher in Group B than in Group A before pregnancy (p < 0.01), and during late gestation and postpartum (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Reassessment of antithyroid drug therapy of Graves' disease

Antithyroid drugs have mainly been used to obtain euthyroidism in patients with chronic hyperthyroidism, whatever the cause, and for long-term medical treatment of hyperthyroidism due to Graves' disease. Endocrinologists are faced with the problem of potential side effects and a high relapse rate (30-50%) after an apparently successful treatment. Despite the use of antithyroid drugs for more than four decades, controlled prospective studies have only recently been carried out, comparing high- versus low-dose antithyroid drug treatment of Graves' disease. The present review focuses on differences in treatment regimens in various areas of the world, efficiency, side effects, and the possibility of predicting relapse at the end of antithyroid drug treatment. Several surveys have recently been taken concerning treatment strategy in various parts of the world. Despite the obvious limitations of surveys carried out by a questionnaire, these studies represent the first important efforts to analyze and compare medical strategies for the management of Graves' disease in Europe, the USA, and Japan, between 1986 and 1992. There were clear indications that American thyroidologists appear to be giving up on antithyroid drug therapy more readily and opting instead for generalized ablative treatment with radioactive iodine. In Europe, on the contrary, radioiodine remains largely limited to specific conditions, and antithyroid drugs still remain the major first-line therapy for Graves' disease. In the future, immunomodulation--either alone or in combination with antithyroid drugs--might improve the medical treatment of Graves' disease. Despite the well-known limitations of antithyroid drugs, their use is simple, safe, and advantageous; European endocrinologists thus challenge the American tendency to ablate almost all patients with radioiodine.

Maternal and neonatal thyroid function at birth in an area of marginally low iodine intake

Thyroid function was evaluated in cord serum of healthy full-term newborns and compared to that of mothers immediately after parturition. The study was carried out in an area without overt iodine deficiency, but with a marginal iodine supply (less than 100 micrograms/day in 80% of women). The aim of the study was to delineate the interrelationships between the thyroid statuses of mother and child at birth. Maternal thyroid function was characterized at delivery by relative hypothyroxinemia; increased T3/T4 ratios, indicating preferential T3 secretion; slightly increased TSH levels within the normal range in 97% of women; increased serum thyroglobulin (TG) values, which were above normal in 60% of women; and also goiter formation in almost 10% of women. The findings indicated glandular stimulation and confirmed our earlier reports that pregnancy constitutes a stress for the maternal thyroid economy, enhanced by the limited availability of iodine in the diet. By contrast, newborns showed a strikingly distinct pattern: there was no relative hypothyroxinemia and free T4 levels were significantly higher than in the respective mothers (19.4 vs. 14.7 pmol/L; P less than 0.001). In spite of these differences, however, mean neonatal TSH and TG levels were significantly higher than maternal values, respectively 6.0 vs. 1.9 mU/L for TSH (P less than 0.001) and 70 vs. 40 micrograms/L for TG (P less than 0.001). Furthermore, neonatal TG and TSH levels increased in parallel and were highly correlated with maternal data, suggesting a regulatory link between both thyroid economies. The results suggested that the common regulatory link is the limited availability of the iodine supply. In conclusion, the present study demonstrates that even in conditions with a marginally low iodine intake, pregnancy constitutes a stimulus for both the maternal and newborn thyroids. Changes in both groups are associated and the abnormalities in TSH and TG are amplified in the newborns. The TSH and TG alterations at birth in full-term healthy newborns, associated with similar alterations in maternal thyroid function, provide evidence for a common stimulatory factor, relative iodine deficiency. The data emphasize the hypersensitivity of neonatal thyroid function to marginal iodine deficiency and point to the need to increase the iodine supply in groups at risk, such as women during pregnancy, and also newborns in the perinatal period.

The management of hyperthyroidism due to Graves' disease in the former USSR in 1991: results of a survey

A survey of the current management of Graves' disease was performed in the USSR among members of All Union Endocrine Society. The questionnaire was based on the format used previously for a survey of members of European Thyroid Association. The aim of a similar survey in the USSR was to obtain a comprehensive pattern of management of Graves' disease in Soviet endocrinology clinics and to compare medical attitudes in the former USSR to those in other European countries. One hundred and twenty questionnaires were mailed with 55 returned (46%). The responses originated from 33 cities, representing major endocrinology centers of the former Soviet Republics. Initial diagnosis was conducted both in hospitals (55%) and ambulatory care settings (45%). Thyroid scintigraphy was requested by 42.3% of the respondents; a majority of them (90%) used 131I. Thyroid ultrasonography was performed in more than 50% of cases. Measurements of cholesterol, total T4 and T3 were the most frequent laboratory tests requested to confirm the diagnosis. For the treatment with ATD, methimazole was the exclusive choice (PTU is not currently in use in the USSR). Beta-blocking agents were prescribed by a majority of respondents. For the long term treatment, a combination procedure of MMI and thyroid hormones was clearly preferred by almost 3/4 of the respondents. A fixed period of treatment was preferred by 62% of the respondents, with a duration of therapy of 18-24 months. Surgery for treatment of the index patient was chosen by only 6%, and radioiodine by 3%. The number of responses was too limited to attempt any characterization of the two latter modalities.

Partial reversibility during late postpartum of thyroid abnormalities associated with pregnancy

The aim of the present work was to assess during late postpartum the reversibility of thyroidal alterations associated with pregnancy. Thyroid function was reinvestigated 6 months after delivery in 100 randomly selected healthy women and thyroid volume was reevaluated 12 months after delivery in 10 other selected women. The subjects had previously been carefully followed during gestation as they were included in a prospective cohort investigation of the regulation of the thyroid during pregnancy, in an area with a limited dietary iodine intake (less than 100 micrograms/day in 85% of the women). Six months after delivery, an overall normalization of thyroid function was observed. However, an increase in the T3/T4 ratio, which was present in half the cases at delivery, was still evident 6 months postpartum, suggesting the persistence of relative iodine deficiency, probably prolonged in some women through breast-feeding. Furthermore, serum thyroglobulin levels, which were increased in half the women at delivery, remained abnormally high in 40% of them 6 months later. Twelve months after delivery thyroid volume, which had increased in average by 54% during pregnancy, had not reverted to the values found during early gestation. Moreover a goiter was still evident in 2/4 cases in whom it had developed during pregnancy. In conclusion, the present study indicates that pregnancy may constitute a prolonged stimulus for the thyroid and shows for the first time that the alterations associated with gestation are not limited to the period of pregnancy, being only partially reversible during late postpartum. In conditions with a limited iodine intake, pregnancy constitutes a risk for the maternal thyroid: goitrogenesis does occur and may be maintained after delivery. The glandular stress of pregnancy may therefore provide a clue to understanding the high prevalence of thyroid disorders in women. The present study provides additional arguments to suggest that iodine supply be increased during pregnancy but also after parturition, in particular in breast-feeding mothers.

Goiter and pregnancy: a new insight into an old problem

Evidence is presented that pregnancy constitutes a goitrogenic stimulus, particularly in conditions with a restricted or even a marginally low iodine intake. In a series of studies carried out in a large cohort of pregnancies in the Brussels area, the authors show that an increase in thyroid volume is observed in a majority of pregnant women, leading to goiter formation at delivery in 9% of the cases. Furthermore, increments in thyroid volume were correlated with biochemical evidences of functional stimulation of the thyroid, such as an elevation in serum TG levels, preferential T3 secretion, and slight increases in basal TSH at delivery. Hence, the association of biochemical features of thyroidal stimulation with volumetric changes in the gland strongly suggests that pregnancy truly induces goitrogenesis rather than vascular swelling ("intumescence") alone, at least in conditions with a low iodine intake. Finally, preliminary data from this laboratory, as well as recently published data from other investigators, suggest that goiter formation during pregnancy can easily be prevented by increasing the iodine supply during pregnancy.

Pregnancy in patients with mild thyroid abnormalities: maternal and neonatal repercussions

A prospective study was undertaken during pregnancy in 120 euthyroid women presenting with mild thyroid abnormalities (TA): 11 with a past history of thyroid disorder, 44 with goiter, 20 with nodules, and 45 with thyroid autoantibodies. The aims of the study were to assess whether the pattern of thyroid alterations during gestation was different in women with TA compared to that in healthy control pregnant subjects and to evaluate possible obstetrical and neonatal repercussions. The overall prevalence of underlying subtle thyroid abnormalities in the cohort was 17%, probably as the result of the environmental moderately low iodine intake. Despite the intrinsic heterogeneity of the four groups of women with TA, the adaptation of the thyroid to the stress of pregnancy was different from that of the control subjects. Noteworthy were 1) the marked elevation of serum thyroglobulin in women with past history of thyroid disorder, goiter and thyroid nodules; 2) the increase in goiter size in a third of the goitrous women, associated with biochemical evidence of functional stimulation of the gland; 3) the indirect evidence of partial thyroidal autonomy in goitrous patients; and 4) the increase in the number and size of thyroid nodules during gestation. Taken together, the data indicated that pregnancy was associated with a greater thyroidal risk in patients with TA compared to healthy subjects. In relation to thyroid autoimmunity, most patients remained euthyroid during gestation, but in a few cases, TSH was elevated at delivery, suggesting diminished thyroidal reserve. Also, 40% of newborns from mothers with thyroid autoimmunity had elevated thyroid peroxidase antibody titers at birth, and there was a highly significant correlation between maternal and neonatal thyroid peroxidase antibody titers. Finally, thyroid autoimmunity was clearly associated with an increased risk of spontaneous abortion (13.3 vs. 3.3%; P less than 0.001). Thyroid function in newborns from mothers with TA was normal and not different from that in controls; similarly, obstetrical features were similar in patients with TA and control subjects. In conclusion, pregnancy is associated with a greater thyroidal risk in women with TA, thereby emphasizing a potential link between pregnancy and thyroid disorders. It is recommended that patients with known, even subtle, thyroid abnormalities be closely monitored during pregnancy, in particular those with a goiter, nodules, or thyroid autoimmunity, especially in areas with a moderately low iodine intake, where the prevalence of mild thyroid disturbances is high.

Differences and similarities in the treatment of diffuse goiter in Europe and the United States

In two separate studies, members of the American Thyroid Association (ATA), and the European Thyroid Association (ETA) were surveyed by questionnaire on their management of Graves' disease. The aim was to determine how expert clinical thyroidologists employ three different therapies which are available for this disorder. Herein we summarize, compare and contrast similarities and differences in the results of these surveys. For the index patient, radioiodine (RAI) was the therapy of choice for 69% of ATA respondents but only 22% of ETA respondents. In contrast, only 30.5% of ATA respondents chose antithyroid drugs as first line therapy compared to 77% of ETA respondents. There was consensus on the relative lack of a role for thyroidectomy. The implications of these differing approaches to the treatment of hyperthyroidism due to Graves' disease are discussed.

Differences and similarities in the diagnosis and treatment of Graves' disease in Europe, Japan, and the United States

In three separate studies, members of the American Thyroid Association (ATA), the European Thyroid Association (ETA), and the Japan Thyroid Association (JTA) were surveyed by questionnaire on their management of Graves' disease. The aim was to determine how expert clinical thyroidologists employ diagnostic procedures and the three different therapies that are available for this disorder. In this report, we identify, summarize, compare, and contrast similarities and differences in the results of these surveys in these three different regions of the world. In general, ATA members used fewer diagnostic tests than did their European or Japanese colleagues. For the index patient, radioiodine was the therapy of choice for 69% of ATA respondents but only 22% and 11% of ETA and JTA respondents, respectively. In contrast, only 30.5% of ATA respondents chose antithyroid drugs as first-line therapy compared to 77% of ETA and 88% of JTA respondents. There was consensus on the relative lack of a role for thyroidectomy except for narrow indications. The implications of these differing approaches for the diagnosis and treatment of hyperthyroidism due to Graves' disease are discussed.

Regulation of maternal thyroid during pregnancy

A prospective study was undertaken in 606 healthy women during pregnancy to evaluate the changes occurring in maternal thyroid economy as a result of 1) the increased thyroid hormone-binding capacity of serum, 2) the effects of increased levels of hCG on TSH and on the thyroid, and 3) a marginally low iodine intake in the population (50-75 micrograms/day). Four main features were observed. First, thyroidal activity adjusted to the marked increase in serum T4-binding globulin: pregnancy was accompanied by an overall reduction in the T4/T4-binding globulin ratio, with lower free T4 and T3 levels, although in most cases free hormone levels remained within the normal range. The adjustment of thyroidal output of T4 and T3 did not occur similarly in all subjects. In approximately one third of the women, there was relative hypothyroxinemia, higher T3/T4 ratios (presumably indicating preferential T3 secretion), and higher, although normal, serum TSH concentrations. Second, high hCG levels were associated with thyroid stimulation, both functionally (lower serum TSH) and anatomically (increased thyroid size). The data are consistent with a TSH-like effect of hCG on the thyroid. Hence, regulation of the maternal thyroid is complex, resulting from both elevated hCG (mainly in the first half of gestation) and increasing TSH (mainly in the second half of gestation). Third, a significant increase in serum thyroglobulin levels was observed throughout gestation, especially during the last trimester. Fourth, increased thyroid volume was common, and goiter formation not uncommon (goiter was found in 9% of women at delivery). In conclusion, the alterations in maternal thyroid function during gestation are intricate and far from fully understood. In areas of marginally low iodine intake, gestation is associated in a significant number of women with relative hypothyroxinemia, increased thyroglobulin, and enlarged thyroid.

Current trends in the management of Graves' disease

Members of the American Thyroid Association were invited to participate in a survey of the management of Graves' disease. One primary case and several variations were provided, which differed in respect to age, sex, goiter size, severity, etc. The questionnaire was based on the format used in a similar survey of members of the European Thyroid Association. The aim of the survey was to determine 1) how expert thyroidologist employ diagnostic procedures for this disorder, and 2) the choice of therapy of the three treatment options and its manner of implementation. Questionnaires were sent only to clinically active members. The overall response rate was 62%. Data analysis was possible on 52% of members surveyed and was performed using SPSS and a specific Fortran program. In the laboratory evaluation of the primary case a radioiodine uptake, scan, serum total T4, and basal TSH were requested by 92%, 47%, 83%, and 66%, respectively, with 84% of respondents using an ultrasensitive TSH assay. For management of the primary case, radioiodine treatment was the first choice of 69% of the respondents. Antithyroid drugs were used briefly (3-7 days) before 131I by 28%, whereas 41% said they would employ thioureas after 131I. Of those using 131I, 66% tailored the dose to achieve euthyroidism as the goal of therapy, while 34% aimed for hypothyroidism requiring T4 replacement. Only 30% of respondents chose thioureas as a first line of treatment (72% propylthiouracil; 28% tapazole). The duration of drug therapy was a predetermined fixed interval for 80% of the respondents, with 90% treating for 1-2 yr. Other specific trends in diagnostic approach and therapeutic preferences were identified for the eight variations on the primary case problem.

Radioiodine therapy in voluminous multinodular non-toxic goitre

Large doses of radioiodine were administered since 1969 to 15 euthyroid patients with compressive voluminous goitres. A decrease in goitre size was observed in all patients (between 15 and 63%, average 39%). Maximal effect on goitre size was attained rapidly, partially already after less than one year and was almost maximal after 24 to 30 months. No significant local adverse reactions were observed; no patient required steroid administration. Hypothyroidism followed radioiodine administration in 30% of the patients after 2 years; after 8 years, all those who had survived were hypothyroid, requiring substitution therapy. In all patients there was a marked improvement in compression symptoms. The use of radioactive iodine therapy constitutes an alternative to surgery in selected patients with large compressive goitres in whom surgery is contraindicated because of age or other medical conditions.

The management of differentiated thyroid cancer in Europe in 1988. Results of an international survey

In order to know how thyroid nodules and differentiated thyroid cancers are investigated and treated in 1988, an international inquiry was performed by mean of a questionnaire based on a well-defined case report of a 35-year-old female with a solitary small thyroid nodule. Clinicians were asked to indicate their diagnostic and therapeutic approaches to the reported case and to some variations. Analysis of the 157 responses from thyroid experts showed that three in vitro tests (sensitive-TSH, free T4 and total T4) and three in vivo tests (99mTc or radioiodide scintiscan, fine needle aspiration and ultrasonography) were performed most frequently. In the case of a solid and cold nodule and in the absence of fine needle aspiration results, 19% of respondents advocated suppressive therapy and 81% surgery. In the same clinical case, but whom fine needle aspiration had been performed and cytology was benign, surgery was advocated by 24%, suppressive therapy by 48% and a regular follow-up without treatment by 28% of respondents. When surgery was performed and the diagnosis was a differentiated thyroid cancer, (near) total thyroidectomy was more frequently chosen than partial thyroidectomy in both papillary (60 and 40%, respectively, of respondents) and follicular (74 and 26%, respectively, of respondents) cancers; 80% of clinicians did not change their surgical technique in relation to histological type of the tumour. Total thyroidectomy was more often recommended in most of the clinical or anatomical variations compared with the basic case report. Pre- or postoperative hormonal therapy was initiated with L-T4 and TSH suppression was controlled by sensitive-TSH and thyroglobulin determinations. After total thyroidectomy, 131I was used with similar modalities for papillary and follicular cancers to ablate a thyroid remnant.

Abnormalities of esophageal transit in patients with sporadic nontoxic goitre

Esophageal transit (E.T.) was investigated in 122 consecutive euthyroid patients with scintigraphically proven goitre, and compared to 26 control subjects. E.T. was quantified using the 81mKr transit time, a highly sensitive technique capable of detecting even minor E.T. disorders. Abnormal E.T. was observed in 39% of goitrous patients, while it was normal in all controls. Occurrence of delayed E.T. was not correlated with either goitre firmness, the presence of symptoms of neck discomfort, difficulties in swallowing, or nodularity. E.T. delay was more frequent and more severe with larger goitres. In addition, E.T. delay was significantly correlated with asymmetry and "low lying" goitres. In summary, the present studies are the first demonstration of frequent E.T. anomalies in goitrous patients. The data suggest that E.T. impairment could be mediated by two mechanisms: a direct compression effect in patients with large, asymmetrical, partially retrosternal goitres; and an indirect functional esophageal anomaly in patients with small goitres.

Cold thyroid nodules in childhood: is surgery always necessary?

In children who present with a cold thyroid nodule the current recommendation is that surgery immediately be performed in view of the high probability of thyroid cancer. Because the incidence of thyroid cancer in children may be decreasing and because extensive experience has been gained in adults with thyroid echography and fine-needle aspiration cytology, we evaluated three consecutive children with cold thyroid nodules by means of these non-surgical techniques. The diagnoses were: thyroid cancer in one patient, thyroid abscess in one and haemorrhagic cyst of the thyroid in one. In the latter two patients, fine-needle aspiration was both diagnostic and therapeutic. We conclude that thyroid echography and fine-needle aspiration of thyroid nodules deserve more extensive evaluation in the paediatric age group.

Plasma exchange therapy for severe Graves' ophthalmopathy

The authors report on the treatment of 11 Graves' disease patients with severe ophthalmopathy by the use of intensive plasma exchange followed by immunosuppression. Results were evaluated by comparing the ophthalmopathy index and the orbital CT scan performed before and after plasmapheresis. Favorable results were obtained in 91% of the patients. The best positive effects of plasmapheresis were observed for soft tissue involvement, proptosis, tonometry, and visual acuity. Furthermore, a significant reduction in the size and density of enlarged extraocular muscles was also found. Six months after withdrawal of immunosuppression, 4 patients presented a moderate recurrence of ophthalmopathy and were treated successfully by a second course of plasmapheresis, followed by short immunosuppression. In conclusion, the use of intensive plasma exchange associated with immunosuppression is an effective approach to the treatment of severe Graves' ophthalmopathy. It yields rapid and dramatic improvements that are maintained in most patients after withdrawal of immunosuppression. Recurrences are still responsive to the beneficial effects of this combined treatment.

In vitro effects of thyroid hormones on red blood cell Ca++-dependent ATPase activity

Thyroid hormones (TH) have been shown to exert a direct stimulatory effect on the Ca++-dependent ATPase from human and other mammalian erythrocytes. In this in vitro system, T4 has been shown to be more effective than T3. In the present study, TH effects on Ca++-dependent ATPase were investigated, using rabbit and human erythrocyte membranes, after preincubation with 10(-10) M T4, in the presence or in the absence of exogenous calmodulin (CaM) (5.10(-12) M to 5.10(-9) M). Ca++-dependent ATPase activity was measured as inorganic phosphate (Pi) release from 1 mM ATP. The results showed that basal Ca++-dependent ATPase activity in rabbits was moderately increased by T4 (1.44 +/- 0.05 vs 1.32 +/- 0.04 mumol Pi/mg protein/90 min, mean +/- SE; p less than 0.05). The time course of Pi release did not show any stimulatory effect of T4 during the first hour of incubation. The effect of T4 became apparent, however, 1 h after the addition of ATP (delta T4: 15%). With human membranes, T4 induced a relative stimulation of the Ca++-dependent ATPase of 8-10% (p less than 0.05) in experimental conditions where the enzyme was not maximally stimulated by CaM (delta CaM over basal activity: 5-40%). In conditions of high CaM stimulation (delta CaM: 50-320%), T4 had no effect. These results confirm that Ca++-dependent ATPase activity is increased by T4. The effect of T4 is small, and appears as a late event during incubation with ATP. Stimulation by T4 is expressed in states of low enzyme activation by CaM.(ABSTRACT TRUNCATED AT 250 WORDS)

Beneficial effects of intensive plasma exchange followed by immunosuppressive therapy in severe Graves' ophthalmopathy

Nine patients with severe Graves' ophthalmopathy were treated by intensive plasma exchange, followed by immunosuppression. Severity of ocular involvement and response to therapy were evaluated clinically by numerical scoring (ophthalmopathy index). Serum thyroid stimulating immunoglobulins (TSI) and urinary excretion of glycosaminoglycans (GAG) were measured immediately before and immediately after plasmapheresis. Plasma exchange was rapidly accompanied by marked clinical improvement in 8/9 patients. The most marked effects were on soft tissue involvement, proptosis, intraocular pressure, and visual acuity. The ophthalmopathy index decreased from 9.7 +/- 4.1 to 5.7 +/- 2.2 (P less than 0.001) after plasmapheresis. Serum TSI levels were initially elevated in 6 patients and remained positive in 3 patients after treatment. Urinary GAG excretion was initially 2- to 12-fold normal levels and was decreased by 60%. After plasmapheresis, patients received immunosuppressive drugs for 3-6 months. The follow-up period, after withdrawal of drugs, ranged from 5 to 38 months with a median of 17 months. The ocular condition remained stable in 6 patients. Three patients had a relapse 1 year after plasmapheresis: they were treated a second time by plasma exchange with subsequent improvement. In conclusion, intensive plasma exchange provided prompt and effective improvement in patients with severe progressive Graves' ophthalmopathy. This therapeutic procedure, followed by immunosuppression, gave long lasting results. Relapses were responsive to plasmapheresis therapy. The data suggest that plasma exchange may represent the best primary treatment for severe progressive Graves' ophthalmopathy.

Absence of circulating desialylated thyroxine-binding globulin in patients with hepatobiliary disease

Thyroxine-binding globulin (TBG) is the major thyroid hormone carrier protein. The molecule contains approximately 10 sialic acid residues which play a key role in the peripheral metabolism of TBG. Since the serum of patients with liver disease often contains large amounts of several desialylated glycoproteins, the aim of the present studies was to characterize circulating TBG and to examine the possible presence of desialylated TBG (dTBG) in 24 patients with a variety of hepatobiliary diseases and selected on the basis of elevated serum levels of desialylated glycoproteins. Using 4 immunochemical techniques applied for the measurement of TBG, for the detection of dTBG and for the characterization of TBG microheterogeneity, the results indicated: a) a wide scatter of serum TBG levels between 4 and 23 mg/l; b) the absence of detectable amounts of dTBG in any of the sera tested; and c) a close similarity between the microheterogeneity of TBG in patients with liver disease with that of control sera or of purified TBG. In conclusion, in patients with acute and chronic liver disease, TBG, although quantitatively modified, remains qualitatively unaltered, suggesting that diseased liver produces fully sialylated TBG and that its catabolism is not impaired.