Screening for thyroid disease of 15-17-year-old schoolchildren in an area with normal iodine intake.

OBJECTIVE: The prevalence of thyroid disease in Swedish schoolchildren is today insufficiently known. The aim of the study was therefore to determine the prevalence of abnormal thyroid function and thyroid autoimmunity in teen-age schoolchildren and to compare the findings with a healthy control group of 60-65-year-old inhabitants from the same community. SETTING: A semirural community of approximately 15,000 inhabitants. DESIGN: Cross-sectional study. MAIN OUTCOME MEASURES: Thyroid volume and serum concentrations of serum thyrotropin (TSH), total and free thyroxine (T4), total and free 3,5,3'-triiodothyronine (T3), and antithyroperoxidase antibodies (TPOAb). RESULTS: Four schoolchildren (7%, 59 screened) had elevated TPOAb concentration, three of the subjects being girls (8%). One girl with a goitre was overtly hypothyroid and one girl showed borderline-high serum TSH concentration suggesting subclinical autoimmune thyroid disease. One euthyroid boy had a goitre and high concentration of TPOAb. The serum free T3 concentration was significantly higher in 15-17-year-old than 60-65-year-old (7.4 vs. 6.4 pmol L(-1), P < 0.001). The concentrations of other thyroid hormones and of TSH in 15-17-year-old did not differ from those of the 60-65-year-old. CONCLUSIONS: We found three cases of thyroid disease in need of immediate attention or later follow-up. The prevalence of autoimmune thyroid disease was high as indicated from TPOAb measurements. Thyroid tests including TPOAb measurement should be performed on wide indications when teenagers seek medical advice. The reference intervals for teen-age children for commonly used first line tests (TSH and free T4) do not differ from those for adults.