Abstract
Objectives: to establish reference ranges for TSH in health adolescents and to estimate prevalence of thyroid disorders in mild iodine-deficiencies region (median UI – 53 µg/L).
Methods: 1179 children (542 male) of 13-16 years old from 23 districts the Sverdlovsk Region were performed. Thyroid ultrasound was done to all the adolescents, and also there were taken blood sample (from 8.00 to 11.00 PM) for determination of TSH and Anti-TPO-Ab (Axsym®, Abbott Diagnostic Division, USA). Samples for establishment of TSH reference ranges were doing according to NCAB criterions and results of thyroid ultrasound. The reference sample from 561 adolescents (271 male) without thyroid diseases, Anti-TPO-Ab AbTpo (<12 mME/L) and normal thyroid volume (WHO, 2001).
Results: the upper TSH limit (P 97,5) was 5,2 mME/L for males and 4,7 mME/L for females (р=0,032). TSH level among 4,1% females and 2,6% males exceeded the established reference ranges. 3 girls had TSH more than 10 mME/L, but the overt hypothyroidism was diagnosed only in one case (0,1%). The prevalence of subclinical hypothyroidism came to 3.3% (39/1179). Subclinical hyperthyroidism was found in 6 adolescents (3 male), 3 of them had TSH<0,1 mME/L and normal fТ4. The incidence came to 0,5%.
Conclusions: we confirmed, that the upper reference limit for TSH among adolescences should be about 5 mME/L; the prevalence of subclinical hypothyroidism in children from iodine deficiency region is about 3.3%.