Establishment of the Thyroid Reference Intervals for the Pediatric Population in the Coastal Karnataka: A Pilot Study

Thyroid hormones significantly influence physical growth, neuropsychiatric development, and higher cognitive functions. Biological reference intervals and clinical decision limits for pediatric population are derived/ extrapolated from adult populations and Western populations, which may lead to erroneous interpretations. After obtaining ethical approval, 522 children were enrolled. 2 ml of fasting blood was collected and tests were performed using Electrochemiluminescence immunoassay on the Roche Cobas 6000 equipment. Statistical analysis was carried out using EZR software; a p value < 0.05 was deemed significant. The reference intervals for TSH differ from the Mayo Clinic-defined reference interval. The upper cut-off for anti-TPO obtained in our study population is 16.9 when compared to the current clinical decision limit of 34. The study also reports statistically significant differences in FT3 and FT4 among males and females in the adolescent age group (13–18 years) and TSH in 4–6 years. To conclude, biological reference intervals for thyroid profiles in the Indian paediatric population show variations when compared to the biological interval currently followed for flagging and clinical decisions in current settings. The use of locally derived reference intervals ensures population validity and appropriate decision-making in diagnosis.