Complete iodide trapping defect in two cases with congenital hypothyroidism: adaptation of thyroid to huge iodide supplementation.

Two cases of congenital defect in iodide trapping mechanism are related. The absence of thyroid and gastric concentration of 99mTcO4 led to the diagnosis. The study of saliva and gastric:serum concentration ratios confirmed the complete defect. The kinetics of radioiodine studied by external detection showed an early simultaneous decay in the thyroid, the stomach and the left ventricle. Thyroid accumulation of 131I, demonstrated by camera imaging, was estimated to be 0.1% at 48 h. It probably originated from simple diffusion. Iodide supplementation was progressively increased to 4.5 g and 10 g day-1 respectively. It resulted in a normalization of all parameters. Huge doses of iodide did not result in any evidence of hyperthyroidism as TSH rose normally after TRH. Intermittent iodide supplementation in one case could not maintain euthyroidism longer than a few weeks. Daily treatment, therefore, seems necessary.

Multifactorial study of prognostic factors in differentiated thyroid carcinoma and a re-evaluation of the importance of age.

A multivariate analysis of prognostic factors has been carried out with 375 cases of differentiated thyroid cancer (DTC) treated in the same centre by total thyroidectomy and 131I therapy. The patients have been followed for 5 to 23 years. The isolated prognostic roles of age, sex, clinical stage and histology were confirmed, but these factors were found to be strongly interrelated. Multifactorial analysis was conducted following Cox's model. It demonstrated that the prevalent role of clinical staging (nodular versus lobar or massive form) is as important as the initial presence of metastases (P = 0.0001). Histological assessment of differentiation, age and sex were of lesser importance. Thus, the most significant prognostic variable is clinical stage. These data must be taken into account when formulating management protocols for DTC.

[Value of the detection of antithyroid antibodies in thyroid pathology]. / Intérêt de la détection des anticorps antithyroïdiens en pathologie thyroïdienne.

Antithyroid microsomal hemagglutination antibody (MCHA) and antithyroglobulin hemagglutination antibody (TGHA) were measured in 629 patients with thyroid disease and 100 controls. Thyroid antibodies were present in 4% of control patients, only in women and at low titer. Thyroid antibodies prevalence was 97% in autoimmune thyroiditis (MCHA: 93%; TGHA: 53%), was 55% in Graves disease before treatment (MCHA: 46%; TGHA: 33%) and 90% in the first year following 131I therapy. Antibodies prevalence was 57% in myxoedema (MCHA: 52%; TGHA: 25%). In patients with iodine overload, antibodies prevalence was 29% in euthyroid patients, 25% in iodine-induced hyperthyroidism and 55% in iodine-induced hypothyroidism. Thyroid antibodies detection should be systematically performed in the routine evaluation of any thyroid disorder. Because of discrepancies between TGHA and MCHA positivity, their simultaneous detection should be performed.

Iodine-induced thyrotoxicosis: analysis of eighty-five consecutive cases.

Iodine-induced thyrotoxicosis was documented in eighty-five cases. Eighty per cent occur in apparently normal thyroid glands; 60% among them occur in males. Amiodarone accounted for 50% of iodine-induced thyrotoxicosis. Mean thyroid hormone levels at diagnosis were: FT1: 21.7 (normal mean: 7.5, arbitrary units); T3: 4.53 nmol 1(-1) (normal: 2.30 nmol 1(-1). Mean 131I- 24-h uptake was 3.5% (normal range in France 25-45%) and was activated by exogenous TSH (mean 27%). The spontaneous cure in nontreated cases was observed within an average 6 months. A phase of biological hypothyroidism (mean FT1: 3.7, T3: 1.23 nmol 1(-1), TSH: 9.6 microU ml-1 (normal TSH range: 1-7 microU ml-1] preceded the return to euthyroidism. Intrathyroid iodine content measured by X-ray fluorescence was high, then fell gradually. Thyroid tissue study showed a large quantity of intrathyroid iodine and the overiodination of thyroglobulin. Histological and electron microscopic studies are reported. Prednisone and in some cases propylthiouracile were found to be effective.

Pulmonary metastases in differentiated thyroid carcinoma. Study of 58 cases with implications for the primary tumor treatment.

Fifty-eight cases of pulmonary metastases (PM) from 831 cases of differentiated thyroid carcinoma (DTC) were studied. PM were found in about 10% of follicular and 5% of papillary tumors. 131I uptake was found in 55% of the cases, irrespective of histology. Twenty-one patients were treated by 131I only and 12 were cured. Micronodular metastases, 92% papillary, with 86% positive 131I uptake and 77% 8-year survival rate, are the most favorable forms. In others the influence of PM size/age, uptake, delay of appearance, presence of cervical or mediastinal lymph nodes is discussed. Occurrence of late PM according to treatment of the primary tumor was 1.3% thyroidectomy + 131I; 3% thyroidectomy; 5% partial thyroidectomy + 131I; 11% partial thyroidectomy only. Thus prevention in DTC of severe PM (28% 8-year survival rate) can best be achieved by complete thyroidectomy + 131I ablation dose.

[Congenital hypothyroidism with probable anomaly of thyroid receptiveness to thyrotropin. 2 cases]. / Hypothyroïdie congénitale avec probable anomalie de la réceptivité thyroïdienne à l'hormone thyréotrope. Deux observations.

Congenital hypothyroidism associated with unresponsiveness to thyrotropin (TSH) is a very rare condition. In the two cases reported the thyroid gland was not enlarged and endogenous THS secretion control was normal: the high TSH levels observed during hypothyroidism returned to normal after thyroid hormone replacement therapy and were normally responsive to TRH stimulation. Thyroid iodide clearance was investigated under various conditions of stimulation and inhibition. In hypothyroidism clearance was normal and TSH levels very high. During replacement therapy clearance seemed to be inversely correlated to levels of circulating thyroid hormones; it was almost nil in euthyroidism. Whatever the level of circulating hormones, clearance was not reactivated by exogenous TSH. In one patient in euthyroidism clearance, which was virtually zero, was unmodified after butyric AMPc stimulation, which suggests that the anomaly lies below the AMPc stage.

[Subacute myopathy revealing hyperthyroidism]. / Myopathie subaiguë révélatrice d'une hyperthyroïdie.

Progressively increasing muscle weakness of the proximal regions of the lower limbs over a period of two months in a 57-year-old woman was found to be due to an undiagnosed hyperthyroidism. Total relief from muscle weakness was obtained when euthyroidism was restored. In spite of its rarity, hyperthyroidal myopathy should be suspected in all cases of acquired myopathic disorders in adults inasmuch treatment of the hyperthyroidism leads to recovery.

Would I-123 di-iodotyrosine provide a harmless deiodination test? Concise communication.

Defective iodotyrosine deiodinase activity may benefit from a specific treatment, thus requiring an unequivocal diagnosis. In reported cases this diagnosis has been obtained from an in vivo deiodination test making use of di-iodotyrosine (DIT) labeled either with I-131 or I-125. Dosimetric calculation indicates that such tests may result in unacceptable irradiation of the thyroid of a child wrongly suspected of having defective iodotyrosine deiodinase activity; therefore other methods are needed. The use of I-123 DIT is shown to be feasible, but even a 1:30 reduction in the thyroid dose still remains too high. Suppression of thyroid I- uptake by ClO4-, together with I-125 DIT, eliminates almost all thyroid irradiation and provides a sensitive, harmless, and rapid test.

Thyroid iodine content measured by x-ray fluorescence in amiodarone-induced thyrotoxicosis: concise communication.

Iodine-induced thyrotoxicosis (liT) is characterized by (a) a low radioiodine uptake, increased by exogenous TSH, and (b) a spontaneous evolution towards cure within a few months. An hypothetical pathogenesis of liT is an initial inflation in the stores of thyroid hormones during iodine excess, followed by their sudden discharge into the circulation. Thyroid iodine content was measured by fluorescent scanning in 10 patients with amiodarone-induced thyrotoxicosis and in various control groups. Results were found to be high at the onset of the disease and to decrease during its course. The data agree with the hypothetical pathogenesis. Furthermore they may permit exclusion of a painless subacute thyroiditis, which is the main differential diagnosis of liT.

[Thyrotoxicosis, then hypothyroidism caused by iodine overload (amiodarone) associated with neuropathy. Failure of plasma exchange]. / Thyréotoxicose, puis hypothyroïdie par surcharge iodée (amiodarone) associées à une neuropathie. Echec des échanges plasmatiques.

A 54-year-old woman, with no previously documented thyroid disease, treated with amiodarone (200 mg/day, five days a week for 33 months) for paroxysmal tachyarrhythmia complicating mitral stenosis, suddenly developed extremely severe thyrotoxicosis. After therapeutic failures with carbimazole and propylthyrouracil (PTU) associated with beta-blockers, she was transferred to intensive care for plasma exchange (PE). Two PE were performed, temporarily aggravating the cardiovascular status of the patient, with no secondary improvement. The quantity of T3 removed was very small, about 1,000 ng per exchange. On the 14th day PTU had to be discontinued (toxic thrombopenia) and only symptomatic treatment was maintained (assisted ventilation, digitalis, hyperalimentation). In the 4th month, while the patient had a high total serum iodine, hypothyroidism developed due to partial block of the organification of the iodine with high TSH and fixation; this state also lasted 4 months. Spontaneous recovery was observed after 8 months. In addition a severe peripheral neuropathy was observed during the hyperthyroid phase confirmed by electromyography, distinct from the signs of thyrotoxic myopathy. This gradually regressed over 7 months and may be attributed to amiodarone therapy. The association of these two successive types of thyroid disorder due to amiodarone is an exceptionally rare phenomenon. Severe thyrotoxicosis generally requires long-term symptomatic therapy, its natural course being towards spontaneous regression. PE are ineffective on the circulating hormonal levels and were dangerous because of the underlying cardiac disease. The development of hypothyroidism at the 4th month is explained by the persistent iodine overload, and therefore prolonged surveillance after withdrawal of therapy is advised. The neurological complication of amiodarone was quite distinct from the hyperthyroid myopathy.

[Unusual concentrations of triiodothyronine in the serum due to anti-T3 autoantibodies]. / Concentrations insolites de la triiodothyronine du sérum dues à des autoanticorps anti-T3.

Abnormally high T3 serum concentrations incompatible with the patients' clinical thyroid status were observed in a case of Graves' disease and in a euthyroid patient with hyperlipaemia. T3 was in the form of immune complexes precipitable by polyethyleneglycol. Specific anti-T3 autoantibodies were detected in the serum gammaglobulin fraction. The T3 affinity constants of these autoantibodies were found to be as high as 1.10(10) and 7.2.10(10)l/mol respectively. The antibodies interfered with radioimmunological T3 determination, resulting in an apparent increase of T3. However, after extraction, true T3 serum levels remained higher than expected. These findings illustrate the importance of hormone concentrations, affinity constants of binding proteins and equilibrium between free and bound forms in the resulting hormonal effect.

[Iodine excess and iatrogenic thyroid pathology (author's transl)]. / Surcharge iodée et pathologie thyroïdienne iatrogène.

Iodine-induced thyroid disorder is frequent. Amiodarone is responsible for more than half cases of iodine-induced hypothyroidism and hyperthyroidism. Iodine-induced hypothyroidism is detected by the Perchlorate discharge test where its positivity suggests failure of the normal iodine organification. An inhibition of the thyroglobulin proteolysis is probably involved in the pathological process of iodine-induced hypothyroidism. Premature infants are unusually sensitive to iodine excess. Hypothyroidism has been induced in 50% of newborns of 34 weeks or less of gestation after the application, for a few days, of iodized antiseptics. Iodine-induced thyrotoxicosis account for 6% of patients with hyperthyroidism. It occurs most frequently in male with prior normal thyroid gland. The main diagnosis features are the activation of the 131I uptake by exogenous TSH and the spontaneous evolution towards cure. However, in some cases, the severity of the thyrotoxicosis or the slow spontaneous resolution require surgical or medical therapy. From different therapeutic trials it seems that only corticoids and Propylthiouracile are useful. PTU, believed as the drug of choice, has however an incomplete and inconstant effect. The histochemical aspects of the iodine-induced hypo and hyperthyroidism let suppose the possibility of some common mechanism.

[Adrenocortical scintigraphy with 131I-19-iodocholesterol. Indications and results in 66 cases of hypercortisolism and hyperaldosteronism (author's transl)]. / Scintigraphie cortico-surrénalienne au 131I-19-iodocholestérol. Indications et résultats dans 66 observations d'hypercortisolisme et d'hyperaldostéronisme.

Scintigraphy was used in 66 patients with biochemically demonstrated hyperactivity of the adrenal cortex in order to determine the nature and site of the lesions. In cases of hypercortisolism, uptake was bilateral in 12 patients with Cushing's disease, unilateral in 7 patients with malignant or non-malignant tumours, and absent in 3 cases of large malignant tumours. In cases of hyperaldosteronism, scintigraphy performed during dexamethasone-induced ACTH suppression showed distinctly asymmetrical uptake in 13 patients with Conn's adenoma (confirmed by surgery as being on the good uptake side in 10 patients), symmetrical in 20 patients with biochemical findings indicating bilaterality, and intermediate in 9 patients. There was no false positive diagnosis of tumour. Scintigraphy appears to be of considerable value for locating adrenocortical lesions, especially small tumours.