Serum thyroglobulin reference values according to NACB criteria in healthy subjects with normal thyroid ultrasound.

Abstract Background: The present study was undertaken to establish serum thyroglobulin (Tg) normal reference values in a large group of healthy subjects. Methods: Four hundred and thirty-eight non-smoking healthy subjects were selected to assess the Tg reference values (209 males, 229 non-pregnant females, age 34.7±13.1 years). Inclusion criteria were: no personal or familial history of thyroid disease, thyrotropin levels from 0.5 to 2.00 mUI/L, negative thyroperoxidase and thyroglobulin antibodies. In addition, the patients had a normal size thyroid (females ≤18 mL, males ≤25 mL) without nodules on the thyroid ultrasound (TUS). According to National Academy of Clinical Biochemistry (NACB) criteria the Tg results were transformed to a logarithmic scale and reference ranges were calculated as mean±2 SD. Results: Serum Tg was measured on the Beckman Coulter UniCel DxI 800 automated platform by the simultaneous 1-step immunoenzymatic Access Thyroglobulin assay (Beckmann-Coulter SA, Nyon, Switzerland). Serum Tg levels were higher in females than in males (p=0.0022). Accordingly, gender-specific reference values were calculated (i.e., males: 1.40-29.2 ng/mL; females: 1.50-38.5 ng/mL). Conclusions: To the best of the authors' knowledge, the first reference interval study for Tg that integrates NACB criteria and TUS assessment for the selection of the reference population is provided here.