Thyroid volume and urinary iodine excretion in schoolchildren in North-Eastern Bosnia.

Abstract

In the past, severe iodine deficiency, endemic goitre and cretinism were documented in restricted areas of Bosnia and Herzegovina. Since 1953, table salt has been fortified with 10 mg potassium iodide/kg salt in order to prevent iodine deficiency disorders in our country. As dietary iodine intake has been considered to be insufficient, the aim of this study was to evaluate the efficacy of compulsory iodine prophylaxis more than 40 years after its introduction. The study took place in 1999 and was designed in a way to cover all 14 communities of Tuzla Canton, situated in North-Eastern Bosnia. A total of 2433 primary schoolchildren (1204 boys and 1229 girls) aged 7–15 years were included in the study. Thyroid size was estimated by neck palpation, by one examiner, and graded according to the WHO/ICCIDD criteria [1]. In addition to a physical examination, thyroid size was assessed by ultrasound in 480 schoolchildren (238 boys and 242 girls) aged 7–14 years, randomly selected. Thyroid volume was estimated using real-time sonography according to Brunn et al. [2]. The criteria used for defining the upper limit of normal for thyroid volume (97th percentile) in children with a normal iodine intake were those proposed by the WHO/ICCIDD [6]. Urine samples were collected at random from 513 subjects. The urinary iodine concentrations were measured by the method based on the Sandell-Kolthoff reaction [3]. Goitre was detected on physical examination in 19.1% (n=466) of all subjects, in 19.8% (n=244) of girls and 18.4% (n=222) of boys. Although goitre prevalence was higher in girls, the difference was not statistically significant (P>0.05). A low grade (grade 1) goitre was observed in 94.5% (n=440) of those children with goitre, while a visible goitre (grade 2) was found in 5.5% (n=26). A lower grade goitre in most of the subjects is a frequent observation in areas with mild iodine deficiency. Goitre prevalence according to age and sex in schoolchildren is reported in Table 1. As expected, it progressively increased with age. No significant difference (P>0.05) was found in the prevalence of goitre between boys and girls in all age groups. The median thyroid volume as determined by ultrasonography increased with age, from 2.7 ml at 7 years to 8.4 ml at 14 years. A significant positive correlation was observed between the thyroid volume and age (r=0.97, P<0.0001), body weight (r=0.98, P<0.0001), height (r=0.98, P=0.0003) and body surface (r=0.99, P<0.0001). When the upper limits of reference thyroid volumes were taken into account [6], we found a goitre prevalence of 12.9% in the studied population. This finding was in accordance with the prevalence of goitre (13.5%) obtained by physical Table 1 Goitre prevalence as detected by physical examination according to age and sex