[The level of IGF-1 and TGF-beta-1 in the blood serum and the thyroid size in children with normal ioduria].

Abstract

Background: Growth factors--IGF-1 and TGF-beta1 are well documented factors regulating proliferation of follicle cells of the thyroid in many experiments in vitro. It has been proved so far that IGF-1 stimulates cellular mitogenesis of thyrocytes, whereas TGF-beta1 inhibits proliferation of follicle cells of the thyroid in experimental conditions.

Objectives: The aim of the study was to evaluate the correlation between serum concentrations of IGF-1 and TGF-beta1 and the size of the thyroid in children with normal ioduria.

Material and methods: In 2002, the study was performed in 4 elementary schools chosen randomly in Białystok and in the Children's Out-patient Clinic of Endocrinology of the Specialist Regional Hospital. The study included 480 children aged 7-13 years from schools and 120 patients at the same age treated with KJ and/or thyroxine for minimum 12 months due to goiter in the Out-patient Clinic of Endocrinology. All children underwent physical examination with palpation of goiter and USG of the thyroid. Iodine concentration was assessed in the morning urine by the catalytic method of Sanedell-Kolthoff. In the second part of the examination, basing on the assessment of the thyroid size as well as the criteria of WHO from 1997 year for body surface and sex, children were divided into 2 subgroups: with goiter and the thyroid gland within the norm. Children aged 9-11 years were qualified and chosen from subgroups to further examinations. In both subgroups (with goiter and normal thyroid gland) blood samples were taken to determine concentrations of TSH, IGF-1, TGF-beta1.

Results: The mean values/median of IGF-1 concentration were statistically significantly increased in children with goiter in comparison with children with a normal thyroid (436.2 vs. 343.8 ng/ml, p=0.047). The mean values / median of TGF-beta1 concentration were statistically significantly decreased in children with goiter when compared to children with the thyroid gland within the norm (17.8 vs. 23.9 ng/ml).

Conclusions: The significantly lower concentration of TGF-beta1 in the serum of children with goiter in comparison with the values in children with normal size of the thyroid gland and a positive correlation between the concentrations of IGF-1 and the size of the thyroid (after excluding the influence of age and body surface) seem to confirm a vital role of IGF-1 and TGF-beta1 in the pathomechanism of goiter.