Decreased birth weight, length, and head circumference in children born by women years after treatment for hyperthyroidism.

CONTEXT: Whether hyperthyroidism influences the birth characteristics of children born several years after treatment is unknown. OBJECTIVE: The objective of the study was to compare birth characteristics in singleton newborns delivered by women previously treated for Graves' disease (GD), toxic nodular goiter (TNG), or nontoxic goiter (NTG). DESIGN: This was a nested case-control design within a national cohort registry study from 1950 through 2006. SETTING: The study was conducted at a university and a hospital center in collaboration. PATIENTS: The birth characteristics of newborns (n = 3421) delivered in a cohort of 43 633 women treated for GD or toxic nodular goiter by radioiodine or surgery (exposed group) at least 1 year prior to pregnancy were compared with newborns (n = 2914) of 45 655 mothers, previously operated for NTG (unexposed group). MAIN OUTCOME: The primary outcome was birth weight, length, and head circumference. The secondary outcome was malformations, gestational age, and type of hyperthyroidism. RESULTS: The birth weight of exposed children was 3431 ± 607 g (mean ± SD) compared with the unexposed, 3520 ± 641 g (P < .001). The cumulative odds ratio (OR) for lower birth weight was 1.29 [95% confidence interval (CI) 1.16-1.43]. The average birth length for the exposed children was 50.0 ± 2.7 cm compared with the unexposed of 50.4 cm ± 2.6 cm (P < .01) [cumulative OR 1.25 (95% CI 1.13-1.37)]. The head circumference was 34.5 ± 1.9 cm among exposed and 34.7 ± 1.8 cm, respectively (P < .001), with an OR of 1.24 (95% CI 1.13-1.35). No differences in birth characteristics were observed between children born after maternal GD or toxic nodular goiter. CONCLUSIONS: Previous GD or TNG may influence the birth characteristics several years after radioiodine or surgical treatment.

Incidence of hyperthyroidism in Sweden.

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 ~40% 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 2003-2005, 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 (TNG=STA+TMNG) 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.

Incidence of hyperthyroidism in Stockholm, Sweden, 2003-2005.

OBJECTIVES: To investigate the incidence of hyperthyroidism in Stockholm County, in those patients who were diagnosed with hyperthyroidism for the first time during the years 2003-2005. DESIGN: All new cases of hyperthyroidism > or = 18 years of age were prospectively registered to calculate the total incidence of hyperthyroidism, as well as the incidence of the subgroups: Graves' disease (GD), toxic multinodular goitre and solitary toxic adenoma (STA). Eight specialized units/hospitals in Stockholm County participated in the registration. The participating physicians were all specialists in medical endocrinology, oncology, nuclear medicine or surgery. RESULTS: During a 3-year period, 1431 new patients of hyperthyroidism were diagnosed in a well-defined adult population (> 18 years of age) of in average 1,457,036 inhabitants. This corresponds to a mean annual incidence of hyperthyroidism of 32.7/100,000. The incidence of GD was 24.5/100,000 per year, toxic nodular goitre was 3.3/100,000 per year and STA was 4.9/100,000 per year. CONCLUSIONS: The total incidence of hyperthyroidism in Stockholm County was found to be 32.7/100,000 per year, of which 75% had GD. There were a higher percentage of smokers among the patients with hyperthyroidism compared with the overall population in Stockholm, but no difference in the frequency of smoking between patients with GD and toxic nodular goitre.