Thyroid Function of Infants Breastfed by Mothers with Graves Disease Treated with Inorganic Iodine: A Study of 100 Cases

Context

We previously reported that inorganic iodine therapy in lactating women with Graves disease (GD) did not affect the thyroid function in 25 of 26 infants despite their exposure to excess iodine via breast milk.

Objective

To further assess thyroid function in infants nursed by mothers with GD treated with inorganic iodine.

Design

Case series

Setting

Tajiri Thyroid Clinic, Japan

Participants

One hundred infants of lactating mothers with GD treated with potassium iodide (KI) for thyrotoxicosis

Main Outcome Measures

Infant blood thyrotropin (TSH) and free thyroxine (FT4) levels were measured by the filter paper method. Subclinical hypothyroidism was defined as TSH ≥10 μIU/mL and ≥5 μIU/mL in infants aged <6 and ≥6 months, respectively.

Results

Overall, 210 blood samples were obtained from 100 infants. The median infant age was 5 (range, 0-23) months; median maternal KI dose, 50 (4-100) mg/day; median blood TSH level, 2.7 (0.1-12.3) μIU/mL; and median blood FT4 level, 1.04 (0.58-1.94) ng/dL. Blood TSH level was normal in 88/100 infants. Twelve infants had subclinical hypothyroidism; among them, blood TSH levels normalized after maternal KI withdrawal or stopping breastfeeding in 3 infants. In 7 infants, blood TSH levels normalized during KI administration without stopping breastfeeding. Two infants could not be followed up.

Conclusion

In Japan, inorganic iodine therapy for lactating women with GD did not affect thyroid function in most of the infants. Approximately 10% of infants had mild subclinical hypothyroidism, but blood TSH level normalized during continued or after discontinuing iodine exposure in all followed up infants.

Effects of Inorganic Iodine Therapy Administered to Lactating Mothers With Graves Disease on Infant Thyroid Function

Context:

The effects of maternal inorganic iodine therapy on infant thyroid function are not well known.

Objective:

This study investigated the effects on infant thyroid function of maternal inorganic iodine therapy when administered to lactating mothers with Graves disease.

Design and Setting:

This study was a prospective case series performed at the Tajiri Thyroid Clinic, Kumamoto, Japan.

Participants:

Subjects were 26 infants of lactating mothers with Graves disease treated with potassium iodide (KI) for postpartum thyrotoxicosis.

Main Outcome Measures:

Infant blood levels of thyroid-stimulating hormone (TSH) and free thyroxine were measured using the dried filter-paper method. Iodine concentrations in breast milk and infant urine were measured on the same day. Subclinical hypothyroidism was defined as a blood TSH level of ≥10 or ≥5 μIU/mL in <6-month-old and 6- to 12-month-old infants, respectively.

Results:

The median age of the infants was 3 months (range, 0 to 10 months). The median KI dose was 50 mg/d (range, 10 to 100 mg/d). High median iodine concentrations were detected in breast milk (15,050 μg/L; range, 831 to 72,000 μg/L) and infant urine (15,650 μg/L; range, 157 to 250,000 μg/L). Twenty-five of 26 infants had normal thyroid function. Although one infant had subclinical hypothyroidism (blood TSH, 12.3 μIU/mL), the TSH level normalized to 2.3 μIU/mL at 2 months after KI discontinuation.

Conclusion:

In Japan, where iodine intake is sufficient, administration of inorganic iodine to lactating mothers with Graves disease did not affect thyroid function in most infants despite high levels of exposure to iodine via breast milk.

Antenatal management of recurrent fetal goitrous hyperthyroidism associated with fetal cardiac failure in a pregnant woman with persistent high levels of thyroid-stimulating hormone receptor antibody after ablative therapy

High titer of maternal thyroid-stimulating hormone receptor antibody (TRAb) in patients with Graves' disease could cause fetal hyperthyroidism during pregnancy. Clinical features of fetal hyperthyroidism include tachycardia, goiter, growth restriction, advanced bone maturation, cardiomegaly, and fetal death. The recognition and treatment of fetal hyperthyroidism are believed to be important to optimize growth and intellectual development in affected fetuses. We herein report a case of fetal treatment in two successive siblings showing in utero hyperthyroid status in a woman with a history of ablative treatment for Graves' disease. The fetuses were considered in hyperthyroid status based on high levels of maternal TRAb, a goiter, and persistent tachycardia. In particular, cardiac failure was observed in the second fetus. With intrauterine treatment using potassium iodine and propylthiouracil, fetal cardiac function improved. A high level of TRAb was detected in the both neonates. To the best of our knowledge, this is the first report on the changes of fetal cardiac function in response to fetal treatment in two siblings showing in utero hyperthyroid status. This case report illustrates the impact of prenatal medication via the maternal circulation for fetal hyperthyroidism and cardiac failure.

[Management of Graves' disease and hypothyroidism in pregnancy]

In the treatment of pregnant patients with Graves' disease, propylthiouracil is preferred over methimazole in early pregnancy because of a possible teratogenicity of methimazole. Methimazole is preferable to propylthiouracil in other time of pregnancy on the basis of severe liver dysfunction occasionally caused by propylthiouracil. Fetal hypothyroidism can be avoided when maternal free T4 levels are maintained at or above the upper normal limit for non-pregnant subjects. However, maternal free T4 should be kept normal for pregnant reference range when pregnancy complications develop. Fetal hypothyroidism in this setting will not affect the infant's development as long as mothers are euthyroid and the infants recover from hypothyroid state within a short time after birth. In hypothyroid women, 1-T4 dose often needs to be increased in pregnancy. Maternal T4 deficiency in early pregnancy has been suggested to affect normal brain development in the offspring. However, it has recently been shown in iodine rich area that no adverse effect on neuropsychological development was seen irrespective of the severity of maternal T4 deficiency. Insufficient iodine intake in the mother can cause low T4 in pregnancy and also inadequate production of T4 in breast-fed infants when sufficient T4 is essential for normal brain development.

Neurodevelopment in children born to hypothyroid mothers restored to normal thyroxine (T₄) concentration by late pregnancy in Japan: no apparent influence of maternal T₄ deficiency

CONTEXT

The importance of maternal T₄ for brain development prior to the onset of fetal thyroid function has been suggested in basic studies, and a correlation between mild maternal T₄ deficiency in early gestation and disturbance of neurodevelopment in progenies has been shown in large case-control studies. These findings suggest that maternal T₄ deficiency in early pregnancy potentially affects neurointellectual development. On the other hand, no apparent adverse effect in children born to mothers with overt hypothyroidism in Japan has been reported where maternal T₄ had been restored to normal by late pregnancy.

OBJECTIVE

We report five cases in Japan showing no apparent effect of maternal T₄ deficiency on neurodevelopment in progenies where low T₄ levels had been corrected by late pregnancy.

METHODS

Five women with overt hypothyroidism detected at 6-16 wk gestation initiated T₄ treatment. Four women restored euthyroidism by the 20th week. One remained in a subclinical hypothyroid state. Developmental scores of their children were evaluated between 25 months and 11 yr of age by either the Tsumori-Inage Infant's Developmental Test or the Wechsler Intelligence Scale for Children-Third Edition and compared to those of corresponding siblings with no exposure to maternal hypothyroidism.

RESULTS

The development scores of all the children turned out to be either normal or advanced.

CONCLUSIONS

In iodine-sufficient areas, maternal T₄ deficiency in early pregnancy does not necessarily affect neurodevelopment. Therefore, other potential factors altering neurodevelopment, such as iodine deficiency, must be investigated.

Persistent high TRAb values during pregnancy predict increased risk of neonatal hyperthyroidism following radioiodine therapy for refractory hyperthyroidism

Serum levels of TSH receptor antibody (TRAb) often increase after radioiodine treatment for Graves' disease, and high-serum levels of maternal TRAb in late pregnancy indicate a risk of neonatal hyperthyroidism. The aim of this retrospective study is to investigate the characteristics of Graves' women who had a history of radioiodine treatment for intractable Graves' disease, and whose neonates suffered from hyperthyroidism. The subjects of this study were 45 patients with Graves' disease who became pregnant during the period from 1988 to 1998 after receiving radioiodine treatment at Ito Hospital. 25 of the 45 subjects had had a relapse of hyperthyroidism after surgical treatment for Graves' disease. 19 pregnancies were excluded because of artificial or spontaneous abortion. In the remaining 44 pregnancies of 35 patients, neonatal hyperthyroidism developed in 5 (11.3%) pregnancies of 4 patients. Serum levels of TRAb at delivery were higher in patients whose neonates suffered from hyperthyroidism (NH mother) than those of patients who delivered normal infants (N mother). Furthermore, serum levels of TRAb in NH mother did not change during pregnancy, although those of 4 patients of N mother, in which serum levels of TRAb before radioiodine treatment were as high as in NH mother, decreased significantly during pregnancy. In conclusion, women who delivered neonates with hyperthyroidism following radioiodine treatment seem to have very severe and intractable Graves' disease. Persistent high TRAb values during pregnancy observed in those patients may be a cause of neonatal hyperthyroidism.

[Current problems in the treatment of Graves' disease in pregnancy and in lactation]

In Graves' patients complicated by pregnancy, both maternal and fetal problems related to the disease can be reduced or avoided by controlling hyperthyroidism. However, optimal treatment for mothers may exert detrimental effects on fetuses. Methimazole may cause "methimazole embryopathy". Antithyroid drug doses that maintain mothers in euthyroid status are sometimes excessive fetuses. Furthermore, successful treatment with surgery or radioiodine occasionally may result in fetal hyperthyroidism due to TSH receptor antibody(TRAb). There are approaches to manage these problems. Propylthiouracil is chosen in treating Graves' disease in early pregnancy. In later pregnancy, maternal free thyroxine is maintained near or somewhat above normal. Ablative therapy is not recommended in women whose TRAb levels are extremely high from the standpoint of fetal thyroid state.

Ratio of serum free triiodothyronine to free thyroxine in Graves' hyperthyroidism and thyrotoxicosis caused by painless thyroiditis

The serum T3 to T4 ratio is a useful indicator for differentiating destruction-induced thyrotoxicosis from Graves' thyrotoxicosis. However, the usefulness of the serum free T3 (FT3) to free T4 (FT4) ratio is controversial. We therefore systematically evaluated the usefulness of this ratio, based on measurements made using two widely available commercial kits in two hospitals. Eighty-two untreated patients with thyrotoxicosis (48 patients with Graves' disease and 34 patients with painless thyroiditis) were examined in Kuma Hospital, and 218 patients (126 with Graves' disease and 92 with painless thyroiditis) and 66 normal controls were examined in Ito Hospital. The FT3 and FT4 values, as well as the FT3/FT4 ratios, were significantly higher in the patients with Graves' disease than in those with painless thyroiditis in both hospitals, but considerable overlap between the two disorders was observed. Receiver operating characteristic (ROC) curves for the FT3 and FT4 values and the FT3/FT4 ratios of patients with Graves' disease and those with painless thyroiditis seen in both hospitals were prepared, and the area under the curves (AUC), the cut-off points for discriminating Graves' disease from painless thyroiditis, the sensitivity, and the specificity were calculated. AUC and sensitivity of the FT(3)/FT(4) ratio were smaller than those of FT(3) and FT(4) in both hospitals. The patients treated at Ito hospital were then divided into 4 groups according to their FT4 levels (A: < or =2.3, B: >2.3 approximately < or =3.9, C: 3.9 approximately < or =5.4, D: >5.4 ng/dl), and the AUC, cut-off points, sensitivity, and specificity of the FT(3)/FT(4) ratios were calculated. The AUC and sensitivity of each group increased with the FT4 levels (AUC: 57.8%, 72.1%, 91.1%, and 93.4%, respectively; sensitivity: 62.6%, 50.0%, 77.8%, and 97.0%, respectively). The means +/- SE of the FT3/FT4 ratio in the Graves' disease groups were 3.1 +/- 0.22, 3.1 +/- 0.09, 3.2 +/- 0.06, and 3.1 +/- 0.07, respectively, versus 2.9 +/- 0.1, 2.6 +/- 0.07, 2.5 +/- 0.12, and 2.3 +/- 0.15, respectively, in the painless thyroiditis groups. In the painless thyroiditis patients, the difference in the FT3/FT4 ratio between group A and group D was significant (p<0.05). Thus, the FT3/FT4 ratio in patients with Graves' disease likely remains unchanged as the FT4 level rises, whereas this ratio decreases as the FT4 level rises in patients with painless thyroiditis. In conclusion, the FT3/FT4 ratios of patients with painless thyroiditis overlapped with those of patients with Graves' disease. However, this ratio was useful for differentiating between these two disorders when the FT4 values were high.

Stimulation of thyroid-stimulating hormone (TSH) receptor antibody production following painless thyroiditis

OBJECTIVE

Development or recurrence of Graves' disease (GD) following painless thyroiditis (PT) has been documented. Therefore, we measured titres of TSH receptor antibodies (TSHR Ab) using a novel sensitive TSHR Ab assay in patients with PT to determine whether PT enhances TSHR Ab production, possibly triggering the development or recurrence of GD.

DESIGN AND MEASUREMENTS

Ninety-two patients who developed PT were studied. Group G consisted of 40 patients with a history of GD (19 patients in remission, 21 who had stopped taking antithyroid drugs during pregnancy). Group P consisted of 52 patients with no history of GD. Serum thyroid hormone levels, thyroid autoantibodies including TSHR Ab, and 123I uptake at 24 h (RAIU) were measured in these patients at the time of PT onset. TSHR Abs were measured by radioreceptor assay using porcine TSH receptors (pTBII) or human TSH receptors (hTBII).

RESULTS

There were no significant differences in serum thyroid hormone levels or pTBII values between groups G and P. Nor was there any significant difference between p- and h-TBII values in group P. There was also no significant difference in pTBII levels before, compared to at the time of PT onset in group G patients. However, hTBII values at the PT onset were significantly higher in the group G than in the group P (7.7 +/- 9.8%vs. 1.4 +/- 5.4%, P = 0.0014). The rate of hTBII positivity was also significantly higher in group G than in group P (12/40 vs. 3/52, P = 0.002). Furthermore, the RAIU in group G patients was significantly higher than that in group P patients (2.8 +/- 2.4%vs. 1.3 +/- 0.9%, P = 0.0002). GD recurrence was observed in seven patients in group G, whose hTBII levels were significantly higher than those of other patients in this group (17.0 +/- 11.8%vs. 5.7 +/- 8.2%, P = 0.02). Of these seven with relapses, five had hTBII values exceeding 15%.

CONCLUSIONS

TBII elevation at the onset of PT in patients with a history of GD was detected by a sensitive hTBII assay. Destruction of the thyroid by PT may trigger GD recurrence in patients with a history of GD.

Three Japanese patients from two families with generalized resistance to thyroid hormone with mutations in exon 9 of the thyroid hormone receptor beta gene

Resistance to thyroid hormone (RTH) is a genetic disorder caused by mutations in the thyroid hormone receptor (TR) beta gene. The mutations are clustered in two regions: exon 9 and exon 10. To date, only one patient with an exon 9 mutation has been reported in Japan. We herein report three patients from two Japanese families with RTH and mutations in exon 9. A 52-year-old woman and her 18-year-old daughter, both with inappropriate secretion of TSH (SITSH) were diagnosed simultaneously with generalized RTH. Molecular analysis revealed a G345D mutation. An 11-year-old girl with SITSH, whose only manifestation was a goiter, had an R338W mutation, which is frequently associated with pituitary RTH. Thus, RTH with mutations in exon 9 of the TR beta gene is not so rare in Japan.

Toxic multinodular goitre in a patient with generalized resistance to thyroid hormone who harbours the R429Q mutation in the thyroid hormone receptor beta gene

The association of resistance to thyroid hormone (RTH) due to a receptor defect with toxic multinodular goitre or with carcinoma of the thyroid has not been previously reported. Previous histopathological studies of the thyroid gland in patients with RTH have revealed changes similar to multinodular goitre, probably due to continuous stimulation by TSH. We report here a case of generalized resistance to thyroid hormone associated with a multinodular goitre, which became toxic. The patient was a 46-year-old Japanese woman who noticed a goitre although she had no symptoms of thyrotoxicosis. Initial examination revealed elevated serum thyroid hormone levels and a normal TSH level. Ultrasonography disclosed a multinodular goitre with cystic lesions. Three years later, the patient complained that the goitre had become larger and that she had developed symptoms of thyrotoxicosis such as palpitation and hyperhydrosis. Progressive hyperthyroxinaemia with relatively suppressed TSH, increased radioiodine uptake and negative anti-TSH receptor antibodies led to the diagnosis of toxic multinodular goitre. Subtotal thyroidectomy was performed, and pathological examination revealed a micropapillary carcinoma within the multinodular goitre. Occurrence of thyroid carcinoma should be considered in RTH because its incidence is high in multinodular goitre. Molecular examination revealed the R429Q mutation in the thyroid hormone receptor beta gene, which is one of the mutations usually manifesting as the pituitary resistance phenotype. That thyrotoxic manifestations appeared only during toxic stage of multinodular goitre in this case suggests that the phenotype of this type of mutation can be dependent on the amount of thyroid hormone.

Thyroid function in wholly breast-feeding infants whose mothers take high doses of propylthiouracil

BACKGROUND

Propylthiouracil (PTU) might theoretically be preferred over methimazole (MMI) during breast-feeding because of its lower milk/serum concentration ratio (0.1 vs. 1.0). The problem is that Graves' disease often relapses during the postpartum period, and high doses of PTU are sometimes needed to control maternal hyperthyroidism) during breast-feeding. However, there are virtually no data on the effects of maternal PTU on thyroid status of infants whose mothers take more than 300 mg PTU daily and who are wholly breast-feeding.

OBJECTIVES

To investigate whether mothers can breast-feed without adverse effects on infants' thyroid status while taking 300 mg or more daily of PTU.

SUBJECTS AND DESIGN

Eleven infants who were wholly breast-fed while their mothers took PTU 300-750 mg daily for Graves' hyperthyroidism were included in this study. In one of the 11 infants, the mother also took iodine 6 mg daily for a limited period. Thyroid status in these infants was evaluated.

MEASUREMENTS

Free T4 (FT4), thyrotrophin (TSH), and TSH binding inhibiting antibody (TBIAb) concentrations were examined at least once in the age range 6 days to 9 months. Maternal blood was also examined for FT4 and TBIAb on the same day, or within a week, of the infants' blood tests. FT4, TSH and TBIAb concentrations at birth were examined, using cord blood, in cases where antithyroid drugs had been continued through delivery.

RESULTS

Three of the 11 infants had TSH concentrations higher than the normal range for adults. In one of the three infants, the TSH concentration, which was determined 19 weeks after birth, was just above the normal range. In the remaining two infants whose mothers had taken PTU through delivery, TSH concentrations, determined within 7 days after birth, were distinctly high, but they became normal while maternal PTU doses were the same as or higher than those at the initial examination. Maternal PTU doses or FT4 concentrations were not significantly correlated with infants' TSH concentrations.

CONCLUSION

Mothers can breast-feed while taking propylthiouracil at doses as high as 750 mg daily without adverse effects on thyroid status in their infants.

[The outcome of treatment with adjusted dose of 131I to thyroid weight for Graves' disease by estimation of effective half life using a single radioiodine uptake measurement]

In the determination of therapeutic 131I doses, it takes several days to measure effective half life (EHL) of radioiodine in thyroid glands (Ordinary method). We suggested the new method to estimate EHL by a single radioiodine uptake measurement (INDEX method). We evaluated the outcome of 131I treatment with these two methods in outpatients with Graves' disease. Eighty outpatients were treated with INDEX method (Group I) and 108 outpatients with Ordinary method (Group O). At the 5-yr follow up, the incidence of hypothyroidism in Group I was 22.5%, subclinical hypothyroidism 8.8%, euthyroidism 30.0%, subclinical hyperthyroidism 13.7% and hyperthyroidism 25.0%. In Group O, 17.6% of the patients were hypothyroid, 16.7% subclinical hypothyroid, 30.5% euthyroid, 9.3% subclinical hyperthyroid and 25.9% hyperthyroid. There were no significant differences between these two methods. We conclude that INDEX method surpasses Ordinary method in timesaver and is equal in effectiveness.

[Diagnosis and treatment of autoimmune thyroid disease (ATD) complicated by pregnancy]

During pregnancy, distinguishing TBII-negative Graves' disease from HCG-related thyrotoxicosis is important. There has been no convincing evidence for any adverse effects of maternal hyper- or hypothyroidism, or thionamides transferred from the mother on fetal organogenesis. In Graves' disease, maintaining maternal free T4 within normal range with thionamides may be preferable to fetal euthyroidism when toxemia of pregnancy or glucose intolerance develops, since there is little evidence indicating fetal hypothyroidism due to maternal ingestion of thionamides can cause intellectual retardation. TBII and/or TSAb levels should be determined by the 3rd trimester in patients with a history of ablative therapy for Graves' disease, and in patients with primary myxedema, in order to predict or treat fetal hyper- and hypothyroidism.

Prolonged suppressed thyroid-stimulating hormone levels in hyperthyroidism in a neonate born to a mother with Graves' disease

We report here a case of neonatal hyperthyroidism born to a mother, whose pregnancy was complicated by poorly controlled Graves' disease. The patient demonstrated exophthalmos and marked goiter at birth, indicating the existence of thyrotoxicosis in utero. The mother's Graves' disease was well controlled in the third trimester, resulting in a slightly lower level of free thyroxine (FT4) in the umbilical cord blood serum; however, thyroid-stimulating hormone (TSH) was undetectable. Thyroid-stimulating hormone remained undetectable for 2 months, while FT4 levels varied in the course. This case suggests that severe and prolonged thyrotoxicosis in utero, due to poor control of pregnancy with Graves' disease, might induce unresponsiveness of the hypothalamo-pituitary system in the newborn.

TSH receptor antibody-associated thyroid dysfunction following subacute thyroiditis

OBJECTIVE

Autoimmunity plays an important role in the development of thyrotrophin (TSH) receptor antibodies and the pathogenesis of Graves' disease and Hashimoto's thyroiditis. On the other hand, subacute thyroiditis is a self-limited inflammatory disease of presumed viral aetiology. The aim of this study was to examine whether subacute thyroiditis triggers TSH receptor antibody-associated thyroid disorders.

PATIENTS

We reviewed 1,697 patients with subacute thyroiditis seen between 1985 and 1995.

DESIGN AND MEASUREMENTS

We measured antibodies which inhibit the TSH binding to the TSH receptor (TBIAb), thyroid stimulating antibodies (TSAb) and antibodies that block TSH action (TBAb). Other thyroid autoantibodies were also determined.

RESULTS

TBIAb became positive in 38 patients following subacute thyroiditis. Thyroid function after the development of TBIAb appeared to be influenced by the bioactivity of the antibody. Hyperthyroidism developed in the presence of TSAb, and so did hypothyroidism in the presence of TBAb, although 21 patients did not have thyroid dysfunction despite high titres of TBIAb. Fifteen out of 17 patients recovered from hyperthyroidism or hypothyroidism after the disappearance of TBIAb sometimes even without medication. TBIAb-positive patients had a high incidence of a family history of thyroid disease and positive anti-thyroid microsomal antibodies. An ophthalmopathy similar to Graves' disease was also observed in 3 patients.

CONCLUSIONS

Subacute thyroiditis may trigger autoreactive B cells to produce TSH receptor antibodies, resulting in TSH receptor antibody-associated thyroid dysfunction in some patients.

Serum leptin concentrations in patients with thyroid disorders

OBJECTIVE

Leptin, the obese gene product, is secreted exclusively by adipocytes and is thought to act as a lipostatic signal that regulates body weight homeostasis. We previously reported that thyroid hormone is one of the up-regulating factors of leptin in vitro. T3, at physiological concentrations, stimulates leptin mRNA expression and leptin secretion by 3T3-L1 adipocytes. The aim of this study was to explore the role of thyroid hormone in the regulation of leptin in humans.

DESIGN AND PATIENTS

A total of 59 non-obese women aged 38.4 +/- 1.8 years (mean +/- SEM) were studied: 19 patients with hyperthyroidism, 17 patients with hypothyroidism, and 23 normal control subjects. The correlation between serum leptin concentrations and body mass index (BMI) was analyzed, and serum leptin levels were compared among the three groups.

MEASUREMENTS

Serum leptin concentrations were measured by radioimmunoassay.

RESULTS

Serum leptin concentrations after logarithmic transformation were correlated significantly (P < 0.05) with BMI in the hyperthyroid (r = 0.46), the hypothyroid (r = 0.84), and normal (r = 0.63) groups. Even though age, body weight, and BMI were similar in all groups, serum leptin levels in the hypothyroid patients (5.30 +/- 1.12 micrograms/l) were significantly (P < 0.05) lower than in the hyperthyroid and normal groups (6.87 +/- 0.66 and 6.58 +/- 0.68 micrograms/l, respectively).

CONCLUSIONS

These results indicate that thyroid hormone may play an important role in the appropriate secretion of leptin in humans.

[The outcome of adjusted accumulation dose of treatment of Graves' disease]

We evaluated the outcome of 131I treatment of Graves' disease in two different protocols (old and new protocol) of adjusted accumulation dose from 1988 to 1995. Adjusted accumulation doses of patients with above 50 g thyroid weights were increased by 5-20 Gy/g tissue in new protocol compared to those in old one. In 166 patients treated with single and plural doses of 131I treatment in 1990 (Group In), the therapeutic doses were calculated according to new protocol and in 130 patients in 1988 (Group Io), according to old one, modification of Quimby's formula. The patients treated with plural doses were classified as hyperthyroidism because the efficacies of the first treatments with 131I were insufficient. At the 5-yr follow up, the incidence of hypothyroid in Group In was 9%, subclinical hypothyroid 17%, euthyroid 30%, subclinical hyperthyroid 7%, hyperthyroid 37%. In Group Io, 11% of the patients were hypothyroid, 6% subclinical hypothyroid, 29% euthyroid, 3% subclinical hyperthyroid, 51% hyperthyroid. The incidence of hyperthyroid in Group In was lower than that in Group Io (p < 0.05). There were no significant differences in hypothyroid and euthyroid. In conclusion, we suggest that an adjusted dose of 131I in relation to the patients' thyroid weight shows some room for improvement.

Effects of propylthiouracil and methimazole on fetal thyroid status in mothers with Graves' hyperthyroidism

Thionamide therapy is a mainstay of the treatment of hyperthyroidism complicated by pregnancy, but it can expose the fetus to hypothyroidism. In terms of fetal thyroid status, propylthiouracil (PTU) has been preferred over methimazole (MMI) based on experimental data on limited transplacental passage, and lower doses have been recommended. However, neither of these practices is supported by convincing clinical evidence. We compared the effect of maternal ingestion of PTU with that of MMI on fetal thyroid status using cord sera at delivery in 77 mothers with Graves' hyperthyroidism who were receiving thionamides and whose free T4 (FT4) levels were within the normal range. We also examined the dose effects on fetal thyroid status in these women. Thirty-four women were taking PTU (group P), and 43 were taking MMI (group M). Neither the mean fetal FT4 nor the mean fetal TSH level was significantly different between the two groups. No significant difference in the occurrence of low FT4 levels or high fetal TSH levels was found between group P and group M (low FT4, 6% vs. 7%; high TSH, 21% vs. 14%). Little relationship was observed between maternal doses and fetal thyroid status; in fact, when low doses of both PTU (100 mg daily or less) and MMI (10 mg daily or less) were administered, high TSH levels in the fetus were observed in 7 of the 34 fetuses (21%) and in 6 of the 43 fetuses (14%), respectively. Higher doses were associated with normal or low fetal TSH levels. These findings demonstrate that in terms of fetal hypothyroidism-inducing potential, there is little reason to choose PTU over MMI. Individualized, not uniformly low, doses of these drugs may prevent fetal hypothyroidism.

[Thyroid disease and reproduction dysfunction]

Thyroid disorders have been implicated in a broad spectrum of reproductive disorders ranging from abnormal sexual development to menstrual irregularities and infertility. Hyperthyroidism in the male is thought to cause gynecomastia. In the female hypo and hyperthyroidism results in changes in cycles length and amount of bleeding. The hypothyroidism in the male has less clear-cut effect on the reproductive system. Long-standing, untreated hypothyroidism is associated with galactorrhea. These abnormalities are reversible with adequate thyroid supplementation or collection of hyperthyroidism. Thus during the investigation of hirsurism, menstrual irregularity, infertility, galactorrhea, and gynecomastia, the possibility of thyroid dysfunction must always be considered.

Bone mineral density after surgical treatment for Graves' disease

Restoration of bone loss associated with thyrotoxicosis follows normalization of thyroid function. However, the extent of bone loss and restoration remain controversial. To clarify whether bone recovery is complete, we examined lumbar and femoral bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA) in 14 thyrotoxic premenopausal women with Graves' disease and 31 premenopausal women treated for Graves' disease by subtotal thyroidectomy who had been in remission for at least 3 years. In the remission group, to exclude the influence of subclinical hyperthyroidism, thyrotropin (TSH) levels were followed and subjects with low levels excluded. Thus, all 31 subjects had normal thyroid hormone levels with transiently or persistently elevated TSH levels post-thyroidectomy. Data from the two study groups were compared with those from healthy premenopausal controls matched for age, height and weight. Mean lumbar (anterior-posterior and lateral), femoral neck, and trochanter BMDs were significantly lower in the thyrotoxic group than in controls (p < .05, all four BMDs). Mean lumbar (anterior-posterior), femoral neck and trochanter BMDs were significantly higher in the remission group than in controls (p < 0.05, all three BMDs). At the time of DXA, the 31 remission subjects showed a significant positive correlation between lumbar BMD and TSH (p < 0.05) and a significant negative correlation between femoral neck BMD and free triiodothyronine (FT3) (p < 0.05). These observations suggest: (1) in premenopausal women, bone loss associated with thyrotoxicosis due to Graves' disease is present but is fully restored when remission is reached after subtotal thyroidectomy; (2) subclinical hypothyroidism after subtotal thyroidectomy may result in higher BMD than that of controls.

Incidence of subacute thyroiditis recurrences after a prolonged latency: 24-year survey

Subacute thyroiditis, which is considered to be a viral disease, rarely recurs after a complete recovery. We evaluated data on 3,344 patients with subacute thyroiditis who were seen at Ito Hospital between 1970 and 1993. Subacute thyroiditis recurred in 48 of 3,344 patients 14.5 +/- 4.5 yr after the first episode. Five patients experienced a third episode 7.6 +/- 2.4 yr after the second. The mean age of the patients at the first, second, and third episode was 38.4 +/- 6.3, 53.1 +/- 8.9, and 57.8 +/- 10.1 yr old, respectively. The mean incidence of a recurrence was 2.3 +/- 0.9% per year. The erythrocyte sedimentation rate and the duration of treatment were each significantly decreased at the second episode as compared with the first. Thus, recurrences of subacute thyroiditis do occur at least in 2% of patients and exhibited relatively mild clinical manifestations.

Defective organification of iodide causing congenital goitrous hypothyroidism

A 26-yr-old Japanese woman with congenital goitrous hypo-thyroidism and sensorineural deafness underwent a thyroidectomy. Examination of the thyroid gland revealed characteristic features of multinodular goiter. The T3 and T4 content in thyroglobulin (Tg) were 0.03 and 0.02 mol/mol Tg, respectively. Iodide incorporation into Tg, using slices of the thyroid tissue, revealed that iodide organification of thyroid tissue from our patient was markedly lower than that of normal controls. Then, guaiacol and iodide oxidation activities of thyroid peroxidase (TPO) in our patient's thyroid tissue were lower than those of normal controls (guaiacol assay: 1.92 vs. 30.0 +/- 5.7 mGU/mg protein; iodide assay: 1.1 vs. 6.6 +/- 2.8 mIU/mg protein). Lineweaver-Burk plot analysis of the oxidation rates of guaiacol and iodide indicated that this patient's TPO had a defect in the binding of guaiacol and iodide, but the coupling activity of the patient's TPO was not decreased compared with those of two normal thyroids. In this case and in control subjects, Nothern gel analysis of TPO messenger RNA from unstimulated and TSH-stimulated thyroid cells revealed a 3.2 kilobase species in the former and four distinct messenger RNA species of 4.0, 3.2, 2.1, and 1.7 kilobases in the latter. Western blot analysis of TPOs obtained from this patient and from control subjects identified the same 107 kDa protein, using antimicrosomal antibody-positive serum. We analyzed the coding sequence in the patient's TPO gene by using polymerase chain reaction technique. A single point mutation of G-->C at 1265 base pair was detected only in the TPO gene, but this point mutation does not alter the amino acid residue. It is possible that posttranslational modification such as abnormal glycosylation may occur in the TPO molecules. Furthermore, it is possible that there are differences in the tertiary structures of the TPO molecules between our patient and normal subjects. The above abnormalities of TPO molecules may play an important role in our patient's dyshormonogenesis.

[Clinical significance of the measurement of the urinary concentration of iodine in differentiating silent thyroiditis from Graves' disease]

In order to differentiate silent thyroiditis (SLT) from Graves' disease, the usefulness of the measurement of the urinary concentration of iodine was evaluated in this study. The subjects employed were 39 patients with SLT and 40 patients with Graves' disease. Patients were advised to avoid any iodine-containing food or medication for a week before the examination. The urinary concentration of iodine (UI) and the serum concentration of thyroid hormones were determined. UI was calculated from the amount of iodine in the spot urine by multiplying it by the ratio of iodine to creatinine. Since the UI value thus obtained was significantly well correlated with the UI value for 24 hour urine, the former value was used instead of the latter value thereafter. Mean UI value in the patients with SLT was 482.4 +/- 296.4 mu g/day and that in the patients with Graves' disease was 169.8 +/- 75.2 mu g/day, the former value being significantly higher than the latter (p < 0.0001). A strong and significant correlation between UI and the serum concentration of FT4 or T3 (TT3) was found in the patients with SLT (r = 0.76, p < 0.0001 and r = 0.54, p < 0.02), but not in those with Graves' disease (r = 0.34, p = 0.07 and r = 0.24, p = 0.14) Mean UI/FT4 ratio and mean UI/TT3 ratio was significantly higher in patients with SLT than those with Graves' disease and the overlaps in the ratios between these two groups were very slight. These results indicate that both the ratios of UI/FT4 and UI/TT3 were useful parameters to differentiate SLT from Graves' disease. The higher UI value observed in the patients with SLT was thought to be due to the increase in the amount of inorganic iodine which was liberated from the iodinated material leaked from the damaged thyroid tissue by the deiodinating mechanism in the peripheral tissues.

[A five-year follow-up of two different 131I treatment methods for Graves' disease and the factors affecting the outcome]

We employed two different methods of 131I treatment for Graves' disease in 285 patients and compared the results between the two. (We also analyzed the factors affecting the treatment outcome.) A single dose of 131I adjusted to the patients' thyroid weight was administered to 180 patients in group 1, while a relatively lower dose of 131I (approximately 30Gy) was given repeatedly to 105 patients in group 2. A 5-year follow-up showed that in group 1, 34% of the patients were euthyroid, 11% hypothyroid, 11% subclinical hypothyroid and 44% still remained hyperthyroid. In group 2, 43% of the patients were euthyroid, 5% hypothyroid, 35% subclinical hypothyroid and 17% hyperthyroid. The factors affecting the outcome of the treatment in group 1 patients were their thyroid weight, the duration of the disease and TRAb levels. No significant correlation was observed between the efficacy of 131I treatment and the patients' sex, age, 24hr 131I-uptake, effective half life of administered 131I or titers of antithyroid antibodies. We conclude that the repeated low dose administration of 131I provides the best outcome in a 5-year follow-up. However, we suggest that an adjusted dose of 131I in relation to the patients' thyroid weight should be employed to obtain a faster therapeutic response.

[Studies on patients with a discrepancy between free thyroid hormones and thyrotropin values]

Thyroid function has been almost exactly evaluated by the measurement of serum free thyroxine (FT4), free triiodothyronine (FT3) and thyrotropin (TSH) concentrations. However, we occasionally experience patients who show a discrepancy between free thyroid hormones and TSH values, and the assessment of thyroid function in such cases is extremely difficult. Thyroid hormone autoantibodies (THAA) interfere with radioimmunoassay (RIA) of FT4 and FT3 by giving inappropriate values. To investigate the incidence of THAA, immune precipitation of patients' sera after incubation with labelled T4 (125I-T4) or T3 (125I-T3) analog tracer was done in 394 patients with thyroid diseases. 9 patients (2.3%) showed an increased binding of 125I-T4 or 125I-T3 analog. Heterophilic antimouse antibodies in a patient's serum (human antimouse immunoglobulin antibodies: HAMA) can interfere in two-site immunometric assays (IMA) using mouse monoclonal antibodies and result in spuriously increased serum TSH concentrations. Manufacturers now customarily add nonspecific mouse immunoglobulins into their assay kits to absorb HAMA and prevent such interference. This approach may not always be enough to prevent HAMA interference in all samples. In 14 thyrotoxic patients with inappropriately high TSH measured by an IMA kit, we measured the levels of TSH by the further addition of mouse serum into this kit. Their serum TSH levels were fully suppressed except for 2 patients with a syndrome of inappropriate secretion of TSH (SITSH). The presence of abnormal albumin in the serum also interferes with RIA of FT4 and FT3. We experienced a female case of Graves' disease treated with methimazole who showed an inappropriately high serum FT3 measured by an analog tracer RIA kit, whose serum FT4, FT3 and TSH were 1.31 ng/dl, 19.3 pg/ml and 1.9 mu U/ml respectively. Although the anti-T3 autoantibody was considered to be present initially, immune precipitation of her serum with 125I-T3 analog tracer gave a negative result. In order to elucidate this finding, Sephadex-G200 chromatography of her serum after incubation with 125I-T3 analog tracer was done. Radioactivity of her serum in albumin fraction was significantly higher than that of normal control serum to indicate the presence of abnormal albumin in the serum. In conclusion, to assess the thyroid function of a patient with a discrepancy between free thyroid hormones and TSH values, it is important to consider the presence of THAA, HAMA, or rarely, an abnormal albumin.

Relationship between silent thyroiditis and recurrent Graves' disease in the postpartum period

We carried out a close follow-up study of 96 episodes of postpartum hyperthyroidism, which developed in women with a history of Graves' disease. Hyperthyroidism had developed 1-6 months (mean +/- SD, 2.3 +/- 1.4) after delivery. Radioiodine uptake (RAIU) values during the thyrotoxic phase, determined after a 1-week restriction of iodine-rich diet, ranged from very low to very high (1-70%). The group with low RAIU values (group L: < 10%, n = 26) and the normal group (group N: 10-40%, n = 33) showed significantly higher urinary excretion of iodine (UI) than the high group (group H: > 40%, n = 37), and UI in group L was comparable to that in patients with silent thyroiditis. TSH binding inhibiting antibody (TBIAb) values were determined in 87 patients at the RAIU testing, and were above normal in most of them: all in group H, 68% in group N, and 52% in group L. The mean TBIAb value in group H was significantly higher than that in group N or L (P < 0.0001 for both). Fifty-one patients in group L and group N were observed without treatment. Of these, hyperthyroidism resolved spontaneously in 39 patients (76%), in whom transient hypothyroidism developed with substantial frequency. Hyperthyroidism subsequently resumed in 18 (46%) of these 39 between 4 and 9 months (mean +/- SD, 7.1 +/- 2.1) after delivery and did not resume in the other 21. RAIU values, determined again during this later phase of hyperthyroidism, were high enough to indicate Graves' hyperthyroidism in all but one patient. During the postpartum period, TBIAb values increased and then declined in the majority of the patients irrespective of the course of hyperthyroidism. Of the 21 patients who maintained euthyroidism after spontaneous resolution of hyperthyroidism, transient increase in TBIAb was observed in 14. These findings suggest that silent thyroiditis commonly develops concomitantly with the activation of Graves' disease and delays or masks the development of Graves' hyperthyroidism.

Maternal hypothyroidism during early pregnancy and intellectual development of the progeny

OBJECTIVE

To investigate whether maternal hypothyroidism before the onset of fetal thyroid function influences mental development of the offspring.

DESIGN

We examined IQs in children in whom the mothers had been hypothyroid during early pregnancy (group 1). The IQs were compared with those of siblings who were not exposed to maternal hypothyroidism during gestation (group 2).

PATIENTS

Group 1 consisted of eight children. Mothers were examined for thyroid status during the fifth to 10th gestational weeks and were found to have distinctly low thyroxine levels and high thyrotropin levels; the levels became normal after thyroxine supplementation by 13 to 28 weeks of gestation. Seven of the eight children had nine siblings who had not been exposed to maternal hypothyroidism during gestation (group 2). Ages at examination were 4 to 10 years in group 1 and 4 to 15 years in group 2.

RESULTS

All children in group 1 showed normal IQs. There was no significant difference in the mean IQ between the children in group 1 who had siblings (112 +/- 11) and their siblings in group 2 (106 +/- 8). Even the subject whose mother had had the lowest thyroxine level (free thyroxine, 2.3 pmol/L) had an IQ similar to that of his sibling.

CONCLUSION

These data provide evidence against the presence of adverse effects of maternal hypothyroidism during early pregnancy on the subsequent mental development of the offspring.

[Cases of Graves' disease with falsely high TSH values due to interfering substances which cross-link with mouse monoclonal antibodies in the TSH assay kits]

It has been reported that highly sensitive two-site immunometric assays occasionally indicate falsely high serum TSH values. A possible reason for this is that heterophilic antibodies interfere with these assays. Recently we had a patient in whom the Delfia TSH kit falsely indicated an elevated serum TSH value. A 29-year-old female was diagnosed as having Graves' disease and was referred to Ito Hospital for surgical treatment. Her thyroid hormone values were distinctly high two months before admission (FT3: 20.7pmol/L, FT4: 42.3pmol/L), but her serum TSH level was normal (1.1mU/l). She was clinically hyperthyroid, and T3 and T4 values determined after ethanol extraction and T3 or T4 analog binding rates did not indicate the presence of T3 or T4 antibodies. Her TSH value became undetectable when mouse IgG was added to the assay. These results suggested that the "normal" serum TSH value was caused by interfering substances such as anti-mouse IgG antibodies which had cross-linked with mouse monoclonal antibodies in the Delfia TSH kit. Another 12 patients who were suspected of having the interfering substances were examined because of the discordance between TSH values and thyroid hormone values. All of the serum TSH values measured using the DELFIA TSH kit decreased when mouse IgG was added. In another case, the presence of serum TSH could not be detected using the Delfia TSH kit but could be measured using the RIABEAD II TSH kit.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of subacute thyroiditis with highly positive thyrotropin receptor antibodies and normal radioiodine uptake]

In this paper, we report on a 40-year-old female with subacute thyroiditis (SAT) who showed high levels of TSH-binding inhibitory immunoglobulins (TBII) and thyroid-stimulation blocking antibodies (TSBAb) from the early stage of the disease. Thyrotoxicosis continued for 2 months and it was subsequently followed by severe hypothyroidism. Levothyroxine was then started. At that time, both TBII and TSBAb were still positive, but they disappeared 6 months later and she remained euthyroid thereafter without treatment. When she was in a thyrotoxic phase and had a suppressed TSH level, her 24-hour radioiodine uptake was not suppressed (11%), and thyroid scan showed partial suppression of uptake in the right lobe. These observations indicate that the presence of TSH receptor antibodies (TRAb) may have modified the changes in thyroid state and the course of SAT.

Effects of iodine on thyroid status of fetus versus mother in treatment of Graves' disease complicated by pregnancy

To investigate the effect of maternal iodine therapy for Graves' disease on fetal thyroid, we examined serum free T4 (FT4) and TSH levels in the fetus vs. those in the mother. Patients who were severely thyrotoxic were not included. Cord and maternal sera were tested at delivery in 35 patients with Graves' disease treated with iodine alone during pregnancy (6-40 mg daily). At the initiation of therapy, the mothers were at 11-37 weeks gestation, and FT4 levels ranged from 28.3-65.8 pmol/L. At delivery, maternal FT4 values ranged from 9.3-42.0 pmol/L, slightly above normal in 22 of the 35 mothers and normal in the other 13. Fetal FT4 levels were above the normal range occurred significantly less often than maternal levels (2 in 35; P less than 0.001), and no fetus had FT4 below normal. In the 13 mothers with normal FT4 levels, all fetal FT4 levels were normal; the fetal TSH level was above normal in 1 and normal in the remainder. A significant correlation was found between cord and maternal FT4 levels (P less than 0.05). In 12 of the 35 mothers, FT4 levels rose after a transient fall during iodine administration. The correlation of cord FT4 and maternal FT4 was closer when these 12 cases were excluded (P less than 0.001). Neither the dose of iodine nor the duration of therapy correlated with thyroid function in fetuses or mothers. Fetal TSH binding inhibitory antibody values strongly correlated with maternal TSH binding inhibitory antibody values (P less than 0.001). These findings indicate that 1) in the treatment of hyperthyroidism due to Graves' disease, iodine seldom if ever exposes the fetus to the risk of hypothyroidism; 2) the fetal thyroid is influenced by the same stimulatory and inhibitory factors as the maternal thyroid; and 3) escape from the inhibitory effects of iodine occurs less often in fetuses than in mothers, which may account at least in part for the lower thyroid status in the fetus compared to that in the mother.

Deceptively high thyroid hormone levels in a neonate due to autoantibodies against thyroid hormones transferred from a mother with Graves' disease

At birth, a clinically euthyroid male neonate was found to have unexpectedly high levels of free T3 and T4 concurrent with a high TSH level. The mother was treated with propylthiouracil for Graves' disease during and after pregnancy. The neonate also had an extremely high titer of TSH receptor antibodies. He soon became clinically thyrotoxic as TSH levels were suppressed and thyroid hormone levels rose. After instituting antithyroid therapy, TSH levels became elevated again, while thyroid hormone levels decreased but were still above normal. Around 3 months after birth, both TSH receptor antibodies and discordance, between the levels of thyroid hormones and TSH, disappeared. Because of high maternal TSH levels in conjunction with an elevated free T3 level at 7 months postpartum, we suspected the presence of autoantibodies against thyroid hormones (AAb). Maternal and infant blood samples were then examined retrospectively for AAb and were detected in all the samples except those of the infant taken more than 3 months after birth. The authors, therefore, suggest that physicians be aware of the presence of AAb in pregnant women with Graves' disease, in order to avoid inappropriate treatment which could lead to fetal and neonatal hypothyroidism.

A case of Graves' disease with false hyperthyrotropinemia who developed silent thyroiditis

We encountered a patient who developed silent thyroiditis during the course of Graves' disease. The diagnosis of silent thyroiditis was made on the basis of a low thyroidal 131I uptake, no response to the thyrotropin releasing hormone (TRH) test, and subsequent hypothyroidism despite the presence of high titers of thyrotropin (TSH) receptor antibody (TRAb) and thyroid stimulating antibody (TSAb). The patient, in addition, had a discrepancy between serum TSH and thyroid hormone values. This was due to the presence of interfering substances that react to mouse IgG in the sera since serum TSH levels were decreased in a dose dependent manner by the addition of increasing amounts of mouse IgG to the sera. It should therefore be noted that silent thyroiditis can develop in patients with Graves' disease. Furthermore, clinicians should be aware that two-site immunoassay kits that use mouse monoclonal antibodies are subject to interference by some substances, possibly antibodies which react to mouse IgG.

Recovery from foetal hypothyroidism: evidence for the safety of breast-feeding while taking propylthiouracil

We assessed the post-natal thyroid function in eight infants of mothers with Graves' disease whose thyroid function at birth was suppressed by maternal ingestion of propylthiouracil during pregnancy. These mothers continued taking propylthiouracil after delivery and breast-fed exclusively (two mothers supplemented their breast milk with a small amount of baby food). The cord free T4 level was slightly but uniformly below the normal range in all eight infants, and the cord TSH level was above the normal in seven infants. The dose of propylthiouracil after delivery ranged from 50 to 300 mg daily, which was equal to, or higher than, that before delivery. All these abnormal values normalized in the infant after birth. Serum samples, from seven of the eight mothers, taken at delivery were examined for TSH receptor antibodies; all were positive. The antibody titre, however, was too low, and/or free T4 and TSH levels were examined too long after delivery, for the antibodies to be the cause of the restoration of the infants' thyroid function. These results assure the safety of breast-feeding for the infants of mothers with Graves' disease taking propylthiouracil.

[Ga-67 scintigram in evaluation of malignant lymphoma of the thyroid originating from chronic thyroiditis]

At the Itoh Hospital, 27 patients with primary malignant lymphoma of the thyroid gland have been diagnosed from April 1985 to April 1988. Within the 27 patients, 8 patients were treated with a diagnosis of chronic thyroiditis during 1 year to 7 years at Itoh Hospital. Ga-67 scintigraphy was performed in the 8 patients as suspected malignant lymphoma. Of the 8 patients, 6 were very strong positive, 1 was strong positive and 1 was weak positive. All patients with Ga-67 strong positive scans should have a biopsy and the scans are helpful to direct the biopsy. Ga-67 scintigraphy is useful in the diagnosis of malignant lymphoma of the thyroid gland.

Evidence against the importance in the disease process of antibodies to bovine thyroid-stimulating hormone found in some patients with Graves' disease

The antibody to TSH (TSH-Ab) found in some patients with Graves' disease may be either an antiidiotype (anti-id-Ab) to the TSH receptor antibody (TRAb) or the antigen (idiotype) for which the anti-id-Ab is in fact TRAb. Four groups have found antibodies to bovine TSH (bTSH-Ab) in Graves' disease patients in a TSH binding-inhibiting immunoglobulin (TBII) RRA that uses [125I]bTSH. In this assay serum samples containing bTSH-Ab give highly negative TBII values. The purpose of this study was to look for any clinical significance of potential idiotypic-antiidiotypic network regulation related to bTSH-Ab. Twenty-one (0.49%) of 4285 Graves' disease patients had TBII values less than the mean -4 SD of normal subjects. In all 21, bTSH-Ab was found by incubation of [125I]bTSH with the patient's serum, and significant inhibition of binding of bTSH-Ab to bTSH by human TSH was found in only 3 of these serum samples. We investigated next whether the binding site of the anti-TSH-Ab mimicked the TSH receptor-binding site. Binding of [125I]bTSH to bTSH-Ab-positive serum was not inhibited by bTSH-Ab-negative, thyroid-stimulating immunoglobulin-positive [(+)], and/or TBII(+) immunoglobulin G. In one patient with human TSH-Ab, TSH-Ab appeared and disappeared, and when TSH-Ab was negative, TBII was positive. Inhibition of [125I]bTSH binding to TSH-Ab by the same patient's serum when that patient was serum thyroid-stimulating immunoglobulin(+), TBII(+), and TSH-Ab-negative was sought but not found. Changes in serum TSH-Ab activity and disease activity were not correlated in this patient. In six untreated patients with Graves' hyperthyroidism with bTSH-Ab, the serum T3 and T4 concentrations and the time required to become euthyroid during antithyroid drug treatment were not significantly different from those in 52 such patients without bTSH-Ab. These data suggest that bTSH-Ab is not an anti-id-Ab to TRAb and that TSH-Ab does not directly modulate the activity of Graves' disease.

Retrospective reevaluation of the significance of thyroid microsomal antibody in the treatment of Graves' disease

The results of treatment were analyzed in relation to serum microsomal antibody (MCAb) titre before treatment in 1185 patients with Graves' disease. The percentage of patients who had ablative therapy because of poor response to antithyroid drug treatment was significantly greater in those with MCAb haemagglutination test (MCHA) titres greater than 1:25,000. With 131I treatment, the patients with MCHA titres greater than 1:6400 responded significantly less to therapy, although the analysis was done in 146 selected patients with certain defined radiation doses and small goitres. With surgical treatment, the percentage of the patients entering into remission was significantly smaller for patients with MCHA titres greater than 1:25,000, because of an increase in both hypothyroidism and relapses. The incidence of hypothyroidism was significantly higher in patients with marked lymphocyte infiltration and/or lymphoid follicles. The degree of these histological findings in Graves' disease was not marked in spite of high MCAb titre and it was significantly different from that in Hashimoto's disease when analyzed in relation to the MCHA titre. These data indicate that in Graves' patients with high MCAb titre, remission is difficult to obtain by treatment, and suggest that the significance of MCAb is different in Graves' disease and Hashimoto's disease. The titre in Graves' disease may be one expression of the activity of this disease.

Antithyroid drug therapy for Graves' disease during pregnancy. Optimal regimen for fetal thyroid status

We compared fetal and maternal serum indexes of thyroid status at delivery in 70 patients with Graves' disease who required therapy with thionamides (such as propylthiouracil) during pregnancy. Forty-three mothers required thionamides until delivery (Group 1), whereas the drugs were discontinued during pregnancy after remission in 27 mothers (Group 2). Maternal free thyroxine levels were closely correlated with cord levels in both groups, being essentially identical in Group 2 but slightly lower in fetuses than in mothers in Group 1. Normal maternal free thyroxine levels did not preclude fetal hypothyroidism. The mothers and fetuses in Group 1 had a significantly higher incidence of antibodies that inhibit thyrotropin binding than did those of Group 2. However, a significant correlation between maternal levels of these antibodies and cord levels of free thyroxine or triiodothyronine was found only in Group 2, in which some maternal and cord thyroxine levels were in the thyrotoxic range at delivery, presumably because therapy was discontinued. These findings indicate that high free thyroxine levels and the presence of antibodies that inhibit binding of thyrotropin are useful indexes of the fetal need for antithyroid treatment, and that the thionamide dosage that maintains maternal free thyroxine levels in a mildly thyrotoxic range seems appropriate for maintaining euthyroid status in the fetus.

Factors predicting the course of diabetes mellitus in hyperthyroid patients

The relationship between changes in glucose tolerance with treatment of hyperthyroidism and various factors that might be relevant to carbohydrate metabolism were investigated in 64 hyperthyroid patients with abnormal glucose tolerance, including 35 cases with fasting plasma glucose (FPG) levels of 140 mg/dl or more. All patients had diffuse toxic goiter. After correction of the hyperthyroidism, glucose intolerance improved in almost all cases, even in cases with fasting hyperglycemia, but diabetes mellitus in patients with FPG above 140 mg/dl and/or delta IRI/delta PG X 30' during a 50-g oral glucose tolerance test below 0.10, persisted. Patients who showed diabetic glucose tolerance even after remission from thyroid dysfunction had significantly lower delta IRI/delta PG X 30' values and a higher incidence of family histories of diabetes mellitus than those not showing diabetic glucose tolerance. There were no significant differences in serum T3 and T4 levels between these two groups of patients. The findings suggest that predisposition to diabetes may be an important factor in persistent glucose intolerance in the hyperthyroidism of Graves' disease. The FPG and delta IRI/delta PG X 30' values may be useful in predicting which patients with hyperthyroidism will have permanent diabetes.

Blocking type antithyrotropin receptor antibody in patients with nongoitrous hypothyroidism: its incidence and characteristics of action

The incidence, characteristics of action, and pathogenetic importance of blocking type anti-TSH receptor antibody were examined in patients with autoimmune thyroiditis. Serum immunoglobulin G (IgG) from 8 of 20 patients with nongoitrous hypothyroidism contained substantial amounts of TSH binding inhibitor immunoglobulin (TBII) activity. Newborn infants of a patient with the greatest TBII activity had neonatal transient hypothyroidism. In sera of patients with goitrous hypothyroidism and euthryoid chronic thyroiditis, only weakly positive or negative TBII activity was found. IgGs of these patients and those of nongoitrous hypothyroid patients without strongly positive TBII activity did not inhibit TSH stimulation of thyroid adenylate cyclase activity. Seven of 8 IgGs which had strongly positive TBII activity significantly inhibited cAMP generation induced by 9.1 mU/ml TSH, and the eighth IgG inhibited stimulation with 0.5 mU/ml TSH. Although the modes of TSH binding inhibition were variable, markedly close correlation was found between TSH binding- and TSH stimulation-inhibiting activities of these 8 IgGs (r = 0.90; P less than 0.01). These IgGs may exert their inhibitory effects on adenylate cyclase activity by inhibiting TSH binding to its receptor.

[An improved method for plasma methimazole assay and its clinical application]

An improved method for plasma methimazole assay using high performance liquid chromatography is described. The plasma samples were treated with sodium bisulfite and ammonium sulfate prior to extraction with chloroform. This pretreatment of the samples raised the extraction coefficient to 90%, while simple extraction yielded only 55%. The minimal detection limit was 0.02 microgram/ml, and the coefficient of variation at the level of 0.2 and 1.0 microgram/ml was less than 5%. Pharmacokinetics of methimazole was studied after a single oral dose (20 mg/m2) in six subjects including two healthy adults and four thyrotoxic children. Plasma levels of methimazole showed a peak concentration of 1.03 +/- 0.25 microgram/ml approximately one hour after the drug administration. Plasma half-life, area under the curve and distribution volume were 4.56 +/- 0.71 hr, 7.05 +/- 0.95 microgram/ml X hr, and 630 +/- 110 ml/kg respectively.

Maternal hyperthyroidism and congenital malformation in the offspring

Six hundred and forty-three neonates from mothers with Graves' disease were examined for major malformations of external organs to compare the influence of maternal hyperthyroidism vs. ingestion of methimazole (MMI) during the first trimester on the incidence of congenital malformations. The subjects were divided into four groups according to maternal therapy and thyroid status during the first trimester as follows: (1) infants whose mothers did not receive MMI and were hyperthyroid (Group 1), (2) infants whose mothers did not receive MMI and were euthyroid (Group 2), (3) infants whose mothers received MMI and were hyperthyroid (Group 3) and (4) infants whose mothers received MMI and were euthyroid (Group 4). The prevalence of malformed infants in these four groups was 6.0% (three of 50), 0.3% (one of 350), 1.7% (two of 117) and 0.0% (none of 126), respectively. The incidence in Group 1 was significantly higher than that in Group 2 (P less than 0.01). There was no discernible dose dependency of MMI on the occurrence of malformations. These findings suggest that maternal uncontrolled hyperthyroidism may cause congenital malformations and that the beneficial role of MMI treatment outweighs its teratogenic effect, if any.

Sequential serum measurements of thyrotropin binding inhibitor immunoglobulin G in transient familial neonatal hypothyroidism

Infants with transient neonatal hypothyroidism, in whom TSH binding inhibitor immunoglobulin G (IgG) (TBII) were sequentially measured, are described. Their mother had been taking thyroid replacement for hypothyroidism due to nongoitrous autoimmune thyroiditis. IgGs inhibiting TSH binding were detected in maternal sera by radioreceptor assay. These IgGs also inhibited the adenylate cyclase response to TSH in human thyroid membranes. Three infants had frank hypothyroidism immediately after birth, and TBII were detected in two of them. In the two surviving infants, hypothyroidism was transient and improved when TBII disappeared from their sera. The profile of TBII in one patient corresponded to the IgG disappearance curve. These findings suggest that the transient neonatal hypothyroidism reported was caused by transplacental transfer of TBII.

Anterior pituitary, thyroid, parathyroid and adrenal responses to subtotal thyroidectomy in patients with Graves' disease

Changes in the serum levels of anterior pituitary, thyroid, parathyroid, and adrenal hormones following subtotal thyroidectomy in 31 patients with Graves' disease were investigated. In 14 patients, rapid ACTH tests were performed on the preoperative and the first, third, and seventh post-operative days. Remarkable differences were not seen with regard to the changes in anterior pituitary hormones or cortisol, compared to those seen during general surgery. As to the thyroid hormones, the serum level of triiodothyronine (T3) decreased markedly after surgery and fell to half that of the preoperative value on the first postoperative day. Thereafter, a low value of T3 was maintained during the early postoperative period. Unlike T3, the serum level of thyroxine (T4) decreased gradually until the 7th post-operative day. The levels of both epinephrine and norepinephrine increased transiently during surgery, but the serum level of norepinephrine increased again on the third postoperative day. In the postoperative period, almost half the number of patients showed an inadequate cortisol response to rapid ACTH tests. It is suggested that the unique responses, such as the rise in serum norepinephrine or an inadequate response of cortisol to ACTH, or hypocalcemia, after subtotal thyroidectomy in patients with Graves' disease is largely due to the rapid decrease of T3 in the hypothyroid state, as was noted during the postoperative period.

Management of atrial fibrillation in the post-thyrotoxic state

This study was designed to investigate the appropriate timing for cardioversion in patients with chronic atrial fibrillation who had been rendered euthyroid from a thyrotoxic state. We carried out a retrospective study of 163 patients with thyrotoxic atrial fibrillation, with a mean follow-up of 34 months. With control of thyroid function alone, 101 patients had spontaneous reversion of atrial fibrillation to sinus rhythm and 62 patients had persistent atrial fibrillation. In those with spontaneous reversion, the longest duration of atrial fibrillation prior to the euthyroid state was 13 months. In those with persistent fibrillation, the shortest duration of atrial fibrillation prior to the euthyroid state was eight months. Almost three-quarters of those with spontaneous reversion had conversion to sinus rhythm within three weeks of becoming euthyroid. No spontaneous reversion occurred if atrial fibrillation was still present after the patients had been in a euthyroid state for four months. This study suggests that spontaneous reversion of atrial fibrillation to sinus rhythm is highly unlikely if the duration of atrial fibrillation before the euthyroid state is achieved exceeds 13 months, or if it is still present after the patient has been in a euthyroid state for four months, Cardioversion should be performed at about the 16th week after the euthyroid state is achieved.