Thyroid Volume Assessment in 3–14 Year-Old Spanish Children from an Iodine-Replete Area

Background/Aims: Few data exist on reference thyroid volumes (Tvols) for Spanish children. The standard tables of the World Health Organization (WHO) are only for children older than 6 years. The present cross-sectional study reports the normal Tvols of 3-14 year-old girls and boys living in Madrid (Spain). Methods: The study subjects were 217 children aged 3-14 years. Urinary iodine was determined, and, on the same day, cervical ultrasound examinations were performed by a single, experienced paediatric radiologist. The sex-specific, upper normal limits for Tvol were then determined, based on age and body surface area (BSA). Results: The median urinary iodine concentration was 120 µg/L (interquartile range 80-184); the population was therefore deemed to fall within the optimum range for iodine nutritional status. Eight children with heterogeneous glandular parenchyma were detected, as were 6 with increased vascularity, and 22 with intrathyroid cysts. Tvol increased with age and BSA in both sexes from the age of 3 years. In girls aged 11-12 years, Tvol was significantly larger than that in boys of the same age. When comparing children 6 years old and above, the 97th percentile Tvols with respect to gender/BSA were similar to WHO reference values, but by gender/age they were 30% larger. Conclusions: This work proposes reference ultrasound-determined Tvols for 3-14-year-old children living in Madrid.