Twenty women, who had been randomly selected from women with subclinical hypothyroidism identified in a population study were treated with L-thyroxine and placebo in a double-blind cross-over design during 2 x 6 months. Three women did not complete the study, one because she moved to another part of the country, and two because of nervousness and sense of tachycardia. None of these 'drop-outs' had any objective signs of overtreatment; they had normal pulse rate and a serum T3 concentration within the reference interval. During L-thyroxine treatment serum procollagen-III-peptide concentration increased in 13 women out of the 17 women completing the study and at the end of treatment the mean concentration was significantly raised (P less than 0.001). Serum concentrations of procollagen-III-peptide then correlated with those of free thyroxine (P less than 0.01), total thyroxine (P less than 0.05), and reverse triiodothyronine (P less than 0.05). The same comparison revealed little or no effect on the concentrations of serum creatine kinase activity, transcortin or sex-hormone binding globulin. Heart rate-corrected preejection period and symptom score decreased (P less than 0.05). Four women starting with L-thyroxine showed a marked and prolonged (4-6 months) rise in thyrotrophin concentration during the subsequent placebo period, but remained clinically euthyroid. Four women (of 17) improved during therapy as judged by psychometric testing and their own rating. We could not by pretreatment observations identify these four women apart from serum free and total 3,5,3'-triiodothyronine concentrations in the lower part of the health-associated reference interval. Subclinical hypothyroidism is common among middle-aged and old women, and our findings indicate that approximately one woman in four with this 'subclinical' condition will benefit from L-thyroxine treatment.

Radioiodine treatment is a significant risk factor for development of TAO in Graves' hyperthyroidism. Smokers run the highest risk for worsening or development of TAO irrespective of treatment modality.

Introduction: The incidence of hyperthyroidism has been reported in various countries to be 23-93/100 000 inhabitants per year. This extended study has evaluated the incidence for w40% of the Swedish population of 9 million inhabitants. Sweden is considered to be iodine sufficient country. Methods: All patients including children, who were newly diagnosed with overt hyperthyroidism in the years [2003][2004][2005], were prospectively registered in a multicenter study. The inclusion criteria are as follows: clinical symptoms and/or signs of hyperthyroidism with plasma TSH concentration below 0.2 mIE/l and increased plasma levels of free/total triiodothyronine and/or free/total thyroxine. Patients with relapse of hyperthyroidism or thyroiditis were not included. The diagnosis of Graves' disease (GD), toxic multinodular goiter (TMNG) and solitary toxic adenoma (STA), smoking, initial treatment, occurrence of thyroid-associated eye symptoms/signs, and demographic data were registered. Results: A total of 2916 patients were diagnosed with de novo hyperthyroidism showing the total incidence of 27.6/100 000 inhabitants per year. The incidence of GD was 21.0/100 000 and toxic nodular goiter (TNGZSTACTMNG) occurred in 692 patients, corresponding to an annual incidence of 6.5/100 000. The incidence was higher in women compared with men (4.2:1). Seventy-five percent of the patients were diagnosed with GD, in whom thyroid-associated eye symptoms/signs occurred during diagnosis in every fifth patient. Geographical differences were observed. Conclusion: The incidence of hyperthyroidism in Sweden is in a lower range compared with international reports. Seventy-five percent of patients with hyperthyroidism had GD and 20% of them had thyroid-associated eye symptoms/signs during diagnosis. The observed geographical differences require further studies.

In patients with heart failure, the influence of codon 49 on the outcome and effect of beta-blockers appeared to be more pronounced than that of codon 389. The more common Ser49Ser genotype responded less beneficially to beta-blockade and would motivate genotyping to promote higher doses for the best outcome effect.

The purpose of this review is to provide an account of our present knowledge about the epidemiology of nonmedullary thyroid carcinoma, to discuss the effects of environment, lifestyle and radiation on the risk of developing thyroid cancer, and to discuss aspects on primary prevention of the disease. In areas not associated with nuclear fallout, the annual incidence of thyroid cancer ranges between 2.0-3.8 cases per 100,000 in women and 1.2-2.6 per 100,000 in men, women of childbearing age being at highest risk. Low figures are found in some European countries (Denmark, Holland, Slovakia) and high figures are found in Iceland and Hawaii. Differences in iodine intake may be one factor explaining the geographic variation, high iodine intake being associated with a slightly increased risk of developing thyroid cancer. In general, lifestyle factors have only a small effect on the risk of thyroid cancer, a possible protective effect of tobacco smoking has been recently reported. Because of the (small) increase in risk of thyroid cancer associated with iodination programs, these should be supervised, so that the population does not receive excess iodine. The thyroid gland is highly sensitive to radiation-induced oncogenesis. This is verified by numerous reports from survivors after Hiroshima and Nagasaki, the Nevada, Novaja Semlja and Marshal Island atmospheric tests, and the Chernobyl plant accident, as well as by investigations of earlier medical use of radiation for benign diseases in childhood. These reports are summarized in the review. There appears to be a dose-response relation for the risk of developing cancer after exposure to radioactive radioiodine. The thyroid gland of children is especially vulnerable to the carcinogenic action of ionizing radiation. Thus, the incidence of thyroid cancer in children in the Belarus area was less than 1 case per million per year before the Chernobyl accident, increasing to a peak exceeding 100 per million per year in certain areas after the accident. It is a social obligation of scientists to inform the public and politicians of these risks. All nuclear power plants should have a program in operation for stockpiling potassium iodide for distribution within 1-2 days after an accident.