L. Baschieri

Environmental Iodine Intake and Thyroid Dysfunction During Chronic Amiodarone Therapy

Amiodarone, an iodine-containing drug used frequently in the treatment of cardiac arrhythmias and angina pectoris, has many effects on thyroid hormone metabolism, including decreasing the production of triiodothyronine (T3) and decreasing the clearance of thyroxine and reverse T3. These effects result in elevated serum thyroxine and reverse T3 concentrations and decreased serum T3 concentrations. In addition, iodine-induced hyperthyroidism or hypothyroidism may occur in patients chronically treated with amiodarone. This study is a retrospective analysis of the incidence of thyroid dysfunction in Lucca and Pisa, West Tuscany, Italy, and in Worcester, Massachusetts. Hyperthyroidism was a more frequent (9.6%) complication of amiodarone therapy in West Tuscany, where iodine intake is moderately low; hypothyroidism was more frequent (22%) in Worcester, where iodine intake is sufficient. In patients receiving chronic amiodarone therapy, clinically suspected hyperthyroidism is best confirmed by showing elevations in serum T3 or free T3 concentrations; hypothyroidism is best diagnosed by showing an elevated serum thyrotrophin concentration. Thyroid function should be carefully monitored in patients receiving amiodarone chronically, especially if they have goiter or Hashimotos thyroiditis.

Treatment of amiodarone associated thyrotoxicosis by simultaneous administration of potassium perchlorate and methimazole

Amiodarone iodine induced thyrotoxicosis occurs frequently in patients residing in areas of mild iodine deficiency and in patients with preexisting goiter. Drug therapy of the hyperthyroidism is often unsuccessful. Twenty-three patients with amiodarone induced thyrotoxicosis were either not treated, treated with 40 mg methimazole daily or with methimazole and 1 gm potassium perchlorate daily for up to 40 days and then with methimazole alone. Thyrotoxicosis was more likely to spontaneously remit in patients without goiter. Therapy with methimazole alone was unsuccessful in inducing euthyroidism in 5 patients with goiter. However, combined therapy with methimazole and potassium perchlorate rapidly alleviated hyperthyroidism in almost all patients with goiter. This drug combination is successful because perchlorate inhibits the active transport of iodine into the thyroid and methimazole blocks the intrathyroidal synthesis of thyroid hormones.

Serum thyroglobulin in thyroid carcinoma and other thyroid disorders

Measurements of serum thyroglobulin (hTg) were performed using a specific radioimmunoassay. Sera with detectable anti-thyroglobulin (anti-Tg) antibody titers (>1∶10) as assessed by passive hemagglutination were discarded. Assays were carried out under conditions in which anti-Tg titers less than 1:10 produced no interference. The assay sensitivity was 1.25 ng/ml and the mean ± SE concentration of serum hTg in 58 control subjects was 9.5 ± 0.9 ng/ml (range< 1.25–27 ng/ml). A slight but significant (p<0.025) increase in the mean hTg level was observed in 12 pregnaint women at delivery (25.7 ± 5.2 ng/ml). Moderate to marked elevations of serum hTg were observed in patients with nontoxic goiter (61.4 ± 15 ng/ml; n = 23), subacute thyroiditis (138 ± 67 ng/ml; n =5), toxic adenoma (129 ±47 ng/ml; n =13), untreated (424 ± 101 ng/ml; n = 35) or treated (328 + 222 ng/ml; n =14) toxic diffuse goiter. 88 patients with thyroid carcinoma and 10 with nonthyroidal malignancies were studied. The mean level of serum hTg was increased in untreated differentiated thyroid carcinoma (89.5 ± 19 ng/ml; n = 13) but not in undifferentiated (10 ±2.9 ng/ml; n =6) or medullary (0.8 ±0.2 ng/ml; =3) carcinoma. In treated differentiated thyroid carcinoma the mean hTg levels were normal (8.2 ± 2.2 ng/ml) in patients (n = 24) with no evidence of either a thyroid residue or metastatic disease, moderately increased (56.6 ± 16 ng/ml) in patients (n =27) with residual thyroid tissue, markedly elevated in patients with lymph node metastases (199 ± 50 ng/ml; n = 15) and extremely elevated in those with bone (4004 ± 982 ng/ml; n = 8) or lung (2520 ± 620 ng/ml; n = 5) metastases. There was no significant difference in serum hTg between functioning (n =23) and nonfunctioning (n =5) metastases as assessed by 131| whole body scan. A slight but significant (p < 0.0005) increase in the mean concentration of hTg was observed in nonthyroidal malignancies (21.7 ±4.5 ng/ml; n = 10). Serial measurements showed a transient increase of serum hTg after131| therapy of differentiated thyroid carcinoma, toxic diffuse goiter or toxic adenoma, with peak values usually occurring within the first three days. A fall of serum hTg after administration of suppressive doses of thyroid hormone to patients with nontoxic goiter and a rise after discontinuation of thyroid suppressive therapy in patients with metastatic differentiated thyroid carcinoma was observed. The present data confirm and extend previous data indicating that serum hTg is frequently elevated in thyroid disease, and that the release of hTg from malignant and nonmalignant thyroid tissue is at least in part thyrotropin (TSH) dependent and it is enhanced by radioiodine therapy. Measurements of serum hTg do not differentiate from benign and malignant thyroid disease, but may be usefullly employed in the follow up of differentiated thyroid carcinoma. Of particular interest was the finding that nonfunctioning metastases may be detected by measurement of serum hTg and that bone or lung metastases are associated with much higher levels of serum hTg than lymph node metastases.

Serum thyroglobulin concentrations and 131I whole body scans in the diagnosis of metastases from differentiated thyroid carcinoma (after thyroidectomy)

SUMMARY. Measurements of circulating thyroglobulin (hTg) and 131I whole body scan were performed in 101 patients with differentiated thyroid carcinoma who had been subjected to surgical thyroidectomy and 131I ablation of remaining thyroid tissue. All 45 patients with positive scans (i.e. functioning metastases) had elevated hTg concentrations. Of fifty‐six patients with negative scans forty‐two had undetectable or very low hTg levels and were considered to be free of metastatic thyroid tissue, whereas fourteen showed the presence of non‐functioning metastases in the clinical and/or radiological examination. In this group of patients, eleven had elevated serum hTg levels while the other three patients had detectable hTg concentrations within the normal range. These results indicate that serum hTg measurements correlate very well with scan findings and have the added advantage of detecting non‐functioning metastases which would not be detected by scanning. We concluded that measurement of serum hTg may be used together with scanning, as the first step in the follow‐up of thyroidectomized patients with differentiated thyroid carcinoma.

Unsuspected Parathyroid Cysts Diagnosed by Measurement of Thyroglobulin and Parathyroid Hormone Concentrations in Fluid Aspirates

Excerpt Parathyroid cysts are rare among cervical masses. A review of the literature shows reports of 152 cervical parathyroid cysts (1-4). Unless the patient has hyperparathyroidism, a cervical ma...

RECIPROCAL CHANGES OF SERUM THYROGLOBULIN AND TSH IN RESIDENTS OF A MODERATE ENDEMIC GOITRE AREA

Subjects living in iodine deficient areas were reported to have elevated serum thyroglobulin (Tg) concentrations. This finding was interpreted as related to thyroid stimulation. Discrepant results, however, were found when serum Tg concentrations were correlated either with serum TSH or with goitre size. In this study we investigated the relationships between goitre size, serum Tg and serum TSH in 488 unselected adult subjects living in an endemic area of North‐Western Tuscany (Garfagnana district). The control group comprised 352 subjects residing in a non‐endemic area. In the endemic area a high prevalence of goitre was found (80·1%), thyroid enlargement being slight to moderate in the majority of cases and very large only in six subjects. Serum Tg concentrations increased and serum TSH levels decreased with the size of goitre. Statistical analysis by the chi‐square cross correlation test showed that the converse changes of serum Tg and serum TSH in relation to goitre size were highly significant. These findings indicate that the increase of serum Tg occurring in endemic goitrous subjects may be related to factors other than TSH stimulation. Functional autonomy of the thyroid may account for the finding of low serum TSH and elevated serum Tg values in patients with large goitres. The present data do not exclude the possibility that the release of Tg is influenced by TSH stimulation, but indicate that other factors may be responsible for the increased levels of Tg found in endemic goitre.

Epidemiologic and Clinical Evaluation of Thyroid Cancer in Children from the Gomel Region (Belarus)

Abstract. This study reviews the epidemiology of thyroid cancer during childhood from the environs of Gomel in Belarus and the clinical data of 64 children aged 4 to 16 years from this area who had been diagnosed with differentiated thyroid carcinoma following the nuclear accident of Chernobyl. One case of thyroid cancer in children (aged < 15 years at diagnosis) was observed during the period 1981–1985 (rate = 0.5; expressed as annual averages per million children under age 15 years in the region of Gomel and period identified) before the Chernobyl accident. Twenty-one cases of thyroid cancer in children were observed during 1986–1990 (rate = 10.5) and 143 (rate 97) during 1991–1994 after the Chernobyl accident. During the first 7 months of 1995, there were 33 more cases of thyroid cancer observed in children. Three children with thyroid cancer were born since 1986 in the Gomel region. A total of 64 children aged 4 to 16 years from this area who had been diagnosed with differentiated thyroid carcinoma had been reviewed by us during the period May to November 1994. The female/male ratio was 1.4:1.0. At the time of the first diagnosis the mean age of the children was 9.4 ± 2.8 years, and at the time of the accident their mean age was 3.8 ± 2.4 years. More than 90% of the patients were less than 6 years of age and 3 were still in utero at the time of the accident. The period of latency between the accident and the first diagnosis was 5.6 ± 1.5 years. Their ages at the time of the first diagnosis and their ages at the time of the accident were significantly correlated (p = 0.001); there was no significant correlation between the age of each child at the time of the accident and the latent period before the onset of carcinoma. The aggressiveness of the tumor, evaluated on the basis of T stage, lymph node status, and lung metastases, did not correlate with age at the time of the first diagnosis or with the age at the time of the accident. The susceptibility of the thyroid to the carcinogenetic effects of radiation, particularly during the first years of life (< 5 years) has clearly been demonstrated. However, there appears to be no correlation between the aggressiveness of the tumor and the age of the patients.

Percutaneous ethanol injection treatment of autonomous thyroid adenoma: hormonal and clinical evaluation

OBJECTIVE We have evaluated the efficacy of percutaneous ethanol Injection as an alternative to surgery and iodlne‐131 treatment in solitary autonomous thyroid adenoma.

IS HUMORAL THYROID AUTOIMMUNITY RELEVANT IN AMIODARONE IODINE-INDUCED THYROTOXICOSTS (AIIT)?

Amiodarone, an iodine containing drug, may induce thyrotoxicosis by an uncertain mechanism. In this study the role of thyroid autoimmunity was evaluated in 28 consecutive patients referred to us because they had become hyperthyroid during long‐term amiodarone administration. Titres of thyroglobulin and thyroid microsomal antibodies, TSH binding‐inhibitory and thyroid stimulating antibodies were evaluated. Underlying thyroid disorders were demonstrated in 20 patients (9 of them had toxic diffuse goitre, seven toxic multinodular goitre and four toxic adenoma), while eight patients did not show any apparent thyroid gland abnormality. Circulating thyroid autoantibodies could be found in all amiodarone iodine‐induced hyperthyroid patients with toxic diffuse goitre and in one with toxic multinodular goitre, whilst they were absent in the other patients. These studies suggest that thyroid autoimmunity has little if any role in the development of thyrotoxicosis in amiodarone treated patients without underlying thyroid disorders. Furthermore, in amiodarone‐iodine‐induced thyrotoxicosis associated with various thyroid diseases, the humoral markers of thyroid autoimmunity show an incidence similar to that observed in spontaneous hyperthyroidism.

HUMAN SERUM THYROTROPHIN MEASUREMENT BY ULTRASENSITIVE IMMUNORADIOMETRIC ASSAY AS A FIRST-LINE TEST IN THE EVALUATION OF THYROID FUNCTION

An ultrasensitive immunoradiometric assay (IRMA) using two monoclonal anti‐TSH antibodies has been used for TSH measurements in basal conditions and after TRH stimulation. The results have been compared with those obtained by conventional radioimmunoassay (RIA). The IRMA method had very high sensitivity (0·07 μU/ml). Detectable serum TSH concentrations were found in all normal subjects by IRMA, but in only 76% by RIA. No overlap was observed with the results obtained by IRMA in untreated overtly hyperthyroid patients, in whom serum TSH was below the limit of detection. The relationship between basal and TRH‐stimulated serum TSH concentrations by IRMA and RIA was evaluated in 176 subjects including normals and patients with untreated and treated hyperthyroidism, functioning thyroid adenoma, non‐toxic goitre and patients on l‐thyroxine therapy. A normal TSH response to TRH was observed in virtually all patients with detectable basal serum TSH by both methods. When patients with undetectable basal serum TSH levels were considered, all but one (98%) had no TSH response to TRH by IRMA. On the contrary using RIA, an absent response was found only in 47% of subjects, a blunted responses in 10% and a normal response in 42%. These data indicate that basal serum TSH measurements by IRMA allows a complete discrimination of normal from hyperthyroid patients and can avoid the need for TRH stimulation tests.