Background and aims: Diffused endemic goiter (DEG) development is not always explained by increased TSH levels. Most DEG patients (pts) have normal TSH concentrations, with tendency to decreased T4 and normal or slightly elevated T3. In the present study levels of thyroid hormones (TH) in pts with various degrees of thyroid size (TS) and weak iodine deficiency (ID) were analyzed.
Material and methods: In total DEG 137pts, aged 216 years were studied: 100 girls (g) (73%), 37 boys (b) (27%). TH-T3, T4, TSH were measured. Results were compared using Students criterion (t-test). For each pt ultrasound was performed and antithyroid antibodies (TPO-Ab, Tg-Ab) were measured. For palpation assessment of TS WHO classification (1980) was used. TS ultrasound data were compared to upper volume limit (ml) in iodine sufficient areas (WHO-IDD Control International Council, 1997). Thyroid volume increase expressed as percentage and palpation results were compared and summarized: IAincrease from 0 to 10%, IB from 10 to 50%, II from 50 to 100%, III above 100% increase.
Results: Hashimoto thyroiditis was excluded based on TPO-Ab, Tg-Ab. Sixteen pts, (g12/b4) with hypothyroidism (3 pts) and subclinical hypothyroidism (13 pts) were excluded T3 levels compared in pts with IB and III TS, were evidently higher in pts with III TS (2.43±0.12 and 3.18±0.14 nmol/l, P<0.001). Significant difference in T3 levels between IB, II TS was not observed. Besides there was no significant difference in T4 levels while comparing various TS. TSH was evidently higher in pts with large goiter both in IB II and IB III TS (2.13±0.2 vs 3.59±0.54 mUI/ml, P<0.05 and 2.13±0.2 vs 3.49±0.35 mUI/ml, P<0.001).
Conclusions: T3 increase in ID areas gives adaptation possibility. Increased sensitivity to TSH may occur when ID is present. This explains relatively high, though normal, TSH levels in pts with large goiter.
03 - 07 May 2008
European Society of Endocrinology