Endocrine Abstracts

Introduction: Subclinical hypothyroidism (SCH) can impair concentration and memory skills. If this is a case among adolescents it may impair learning abilities, which in turn may be the cause of poorer performance on various tests and exams. Therefore, the aim of this study was to evaluate the prevalence of SCH in teenage girls attending the gymnasia in the city of Starogard Gdański.

Material and methods: In total 487 girls (age range 11.5–14.7 years) participated in this study. Five milliliter of venous blood was drawn and serum TSH concentrations were measured. In all the participants whose serum TSH concentrations were in the 3rd tertile (> 2.7 mU/l) serum concentrations of fT₄, anti-thyroid peroxidase (ATPO) and anti-thyroglobulin (ATG) antibodies were measured as well as the ultrasonography of their thyroid gland was performed (n=122).

Results: Serum TSH concentrations ranged from 0.18 to 55.76 mU/l (median 2.21 mU/l) and the calculated reference range was 0.94–4.31 mU/l. Serum TSH concentrations >4.31 mU/l were found among 5.5% (n=27) of our participants. Subjects with serum TSH > 4.31 mU/l had a significantly lower body weight and height compared to those with serum TSH concentrations <4.31 mU/l. There was also a smaller percentage of girls after menarche among the subjects with serum TSH >4.31 mU/l (40.7 vs 62.6%, P=0.023). In the USG of the thyroid gland, 54.1% of the subjects with serum TSH > 2.70 mU/l presented decreased echogenicity. Serum levels of ATPO and ATG were elevated in 12.3 and 10.9% of girls, respectively and correlated significantly with the serum TSH concentrations (P<0.01).

Conclusions: The prevalence of SCH in our cohort was 5.5%. Compared with girls whose serum TSH values were below the upper limit of the calculated reference range they had significantly lower body weight and height and were less likely to be after menarche. If this state of mild thyroid dysfunction can have an impact on their cognitive functions warrants further studies.