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 t oday insufficiently known. The aim of the study was therefore to determine the prevalence or abnormal thyroid function and thyroid autoimmunity in tee n-age schoolchildren and to compare the findings with a healthy control gro up 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 thy rotropin (TSH), total and free thyroxine (T4), total and free 3,5,3'-triiod othyronine (T3), and antithyroperoxidase antibodies (TPOAb). Results. Four schoolchildren (7%, 59 screened) had elevated TPOAb concentra tion, three of the subjects being girls (81%). One girl with a goitre was o vertly hypothyroid and one girl showed borderline-high serum TSH concentrat ion suggesting subclinical autoimmune thyroid disease. One euthyroid boy ha d it goitre and high concentration of TPOAb. The serum free T3 concentratio n 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 o f 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 a ttention or later follow-up. The prevalence of autoimmune thyroid disease w as high as indicated from TPOAb measurements. Thyroid tests including TPOAb measurement should be performed on wide indications when teenagers seek me dical advice. The reference intervals for teen-age children for commonly us ed first line tests (TSH and free T4) do not differ from those for adults.