Thyroid ultrasonography is a simple diagnostic method for assessing the prevalence of goitre in children, parameter useful in the estimation of iodine supply. The normal limits recommended by WHO and ICCIDD (following the ThyroMobil study) have been debated by studies which found smaller values, even in regions included in the ThyroMobil study.
Aim: To assess the importance of the inter- and intra-observer differences in the determination of thyroid volume in children.
Material and methods: Thyroid volume in 30 children was estimated using the rotating ellipsoid formula by 3 different observers. One of them determined twice the volume in 25 children.
Results: Mean interobserver variations were 9.51 +/- 8.8%. More important differences were between observer 1 and 3. The differences between every diameter were between 12 and 16%, more important for the longitudinal one. The intraobserver differences were 6.29 +/- 6.12%. We did not find a relation between the value of the thyroid volume and the interobserver (r2 = 0.13, p > 0.05) or intraobserver (r2 = 0.15, p > 0.05) differences.
Conclusions: Interobserver variation may be important, and can partially explain the disagreements on thyroid volume in children. Intraobserver differences, although present, are less calculated. It is important to establish standards for each geographical area and, as much as possible, by the same person. In order to obtain comparable data the techniques of the ultrasound volume evaluation should be harmonized.