New Reference Values for Thyroid Volume by Ultrasound in German Children and Adolescents From a Population-Based Study

Reliable reference values for thyroid ultrasound measurements are essential to effectively guide individual diagnostics and direct population-level health care measures, such as iodine fortification programs. However, the latest reference values for total thyroid volume (Tvol) provided by the World Health Organization (WHO) in 2004 only apply to the 6- to 12-year-old age group and are limited to countries with a long history of iodine sufficiency, which does not reflect the situation in most European countries, including Germany. This study aims to derive up-to-date thyroid volume ultrasound reference values in German children and adolescents. Data from the baseline assessment of a nationwide study in German children and adolescents (KiGGS) conducted between 2003 and 2006 were used to determine sex-specific reference values for Tvol in thyroid-healthy participants aged 6 to 17 years by age and body surface area according to the lambda-mu-sigma method. Data from 5559 participants were available for reference chart construction (2509 girls [45.1%]). On average, the 97th percentile is 33.4% and 28.5% higher than the corresponding WHO reference values for boys and girls, respectively. These findings are consistent with most other studies in German and European children and adolescents at a similar time of investigation. Notably, the sample used for this study was iodine-sufficient according to WHO criteria. The reference values provided by the WHO are overly conservative for this population and could potentially apply to other European countries with a similar history of iodine supply.