Endocrine Abstracts

Background: the iodine supplementation introduced from 2005 by a nationwide program of iodine prophylaxis on a voluntary basis led to iodine sufficiency in Italy. Aim of the present work was to evaluate the modification of thyroid volume (TV) according to the change of iodine status.

Methods: We retrospectively revised 400 subjects submitted to neck ultrasound, with no history of thyroid diseases. We measured TV according to the ellipsoid formula, BMI and TSH. Exclusion criteria were: an inhomogeneous ultrasound pattern or nodular lesions; TSH <0.6 and >4.5 mU/l; obesity and treatment with drugs affecting thyroid function. Non-normally distributed data are expressed as median (95% CI) and normally distributed values as mean ± SD.

Results: We preliminary analyzed data about 200 subjects (100 F, 100 M), with normal median TSH levels of 1.6 (range 1.5-2.2) mU/l, aged 42 (42-46.3) years, with males significantly older than women (P < 0.01). Overall median TV was 8.5 (8.6-9.5) ml. Median TV was significantly higher in males [10.1 (range 10-11.2) ml], compared with females [7 (range 6.8-7.9) ml], (P < 0.0001), leading to the following reference range: 2.9-11.1 ml for females and 4.6-15.97 ml for males, respectively. Overall, median BMI was 22.5 (range 22.3-23.5) kg/m², and higher in males compared with females [21.5 (21.2-22.7) vs 23.9 (23.3-25) kg/m², P < 0.0001]. A significant positive correlation (Spearman r, 95%CI) was found in both groups between TV and age (r 0.26, 0.1-0.38), weight (r 0.6, 0.47-0.71), height (r 0.53, 0.39-0.65) and BMI (0.47, 0.32-0.6) (P < 0.001).

Conclusions: Iodine supplementation in the population appears to have led to a mean reduction of about 2 ml in TV compared with a previous Italian study (1) which reported a mean volume of 12.9±3.6 in males and 9.2±2.9 ml in females. The positive, although weak, correlation with age strengthen this hypothesis, as older people have been exposed to a mild iodine deficiency during childhood and adult age, possibly leading to increased thyroid size. We are now recruiting more individuals in order to obtain normative data for different age groups.

References: Rago T et al, 2001 doi: 10.1007/BF03343926.