Pediatric Reference Ranges

Thyroid disease in children is associated with impaired physical and cognitive development. While there are many well-established reference intervals for the results of tests performed on adults, this is not the case for children. Age-specific reference intervals are critical for proper clinical interpretation of test results; however, a variety of testing challenges make it difficult for laboratories to establish accurate reference intervals for children.

Siemens Healthineers understands the complexity of collecting blood from infants and children for the establishment of reference intervals and the extensive time required for your lab to collect, run, and analyze samples. We can help your laboratory meet the challenges involved in establishing reference intervals for tests performed in the pediatric setting.  

Siemens conducted extensive studies to establish pediatric reference intervals, with data from three separate age groups. The data represented in the following tables includes age groups from 30 days of life to 20 years, with relevant subsets from this pediatric population.


The pediatric samples were collected prospectively from apparently healthy pediatric subjects under consent/assent. Eight collection sites located across the U.S. collected the samples and shipped them frozen to a single laboratory for testing. Three age subgroups were included:


  • Infants: subjects 1 month to 23 months of age
  • Children: subjects 2 to 12 years of age
  • Adolescents: subjects 13 to 20 years of age


Reference intervals were established across genders, and approximately equal numbers of males and females were included. Reference intervals for infants (1 month–23 months), children (2–12 years), and adolescents (13–20 years) for the thyroid hormones were established according to CLSI guideline C28-A3c.1 

Samples from healthy euthyroid individuals were considered normal if they met the strict inclusion criteria. All patients were screened for the presence of thyroid autoantibodies and risk factors for thyroid disorders. For each assay tested, the lower and upper reference limits were estimated as the 2.5 and the 97.5 percentiles of the distribution of test results for each of the two older subgroups. For the infant subgroup, a robust measure of location and spread, as developed by Horn and Pesce, was used for obtaining reference intervals.2 Close to 400 pediatric subjects were included in the final analysis of the combined study.** As a result of the stringent study design, you can be assured of the accuracy and robustness of these reference intervals.