Ultrasonographic determination of goiter prevalence in southern Brazilian schoolchildren

Abstract

The aim of the present study was to estimate the prevalence of goiter in schoolchildren in a formerly iodine-deficient region in southern Brazil by assessing the relationship between body surface area (m2) and thyroid volume (ml) measured by ultrasonography. A populationbased sample of 1,094 randomly selected schoolchildren (6 to 14 years; 556 boys and 538 girls) underwent clinical evaluation. A total of 119 (10.9%) children were diagnosed with goiter upon clinical examination according to WHO criteria (grade Ia: 65, grade Ib: 24, grade II: 29, grade III: 1). Of these, 85 underwent ultrasonography. In order to ascertain the absence of goiter in the 975 schoolchildren with a negative result upon clinical examination, one of ten children was randomly selected for ultrasonography. Sixty-two children agreed to be submitted to the exam. Thus, 147 schoolchildren were evaluated by ultrasonography (7.5-MHz transducer). Goiter was considered to be present when the thyroid volume:body surface area index was >6.2 ml/ m2. The estimated prevalence of goiter if all schoolchildren had been submitted to thyroid volume measurement by ultrasound was 7.2%; it was higher in the lower socioeconomic class (8.2%) than in the upper (7.8%) and middle classes (6.5%). In conclusion, the prevalence of goiter in schoolchildren of this region was higher than in other iodinesufficient areas, especially in lower socioeconomic classes. Goiter in this region may be associated with naturally occurring goitrogens that operate more intensively among less privileged individuals.