Reference range of thyroid hormones in normal Indian school-age children

Area of Science:

• Endocrinology
• Pediatric Health
• Clinical Chemistry

Background:

• Limited data exists on normal thyroid function test values in Indian children.
• Ongoing debate regarding the TSH reference range in adults necessitates pediatric data.

Purpose of the Study:

• To establish age-specific and sex-specific reference ranges for thyroid hormones (FT3, FT4, TSH) in Indian school-age children.
• To provide a basis for accurate diagnosis and management of thyroid disorders in pediatric populations.

Main Methods:

• A large cohort of 9527 children (6-19 years) from Delhi schools were screened.
• A reference population (N=5122) was selected by excluding individuals with thyroid disease history, goiter, or abnormal thyroid antibody levels.
• Serum FT3, FT4, and TSH levels were measured and reference ranges established for each year of life.

Main Results:

• Reference intervals for FT3, FT4, and TSH were determined for boys and girls separately for each year of age.
• In the reference population, mean serum TSH ranged from 1.83-3.58 mIU/l (girls) and 2.57-3.6 mIU/l (boys).
• The 97th percentile for TSH was 5.28-8.04 mIU/l (girls) and 6.01-8.4 mIU/l (boys), indicating current upper limits may be appropriate for children.

Conclusions:

• This study provides comprehensive, sex-specific, and age-specific reference intervals for FT3, FT4, and TSH in Indian children.
• The established ranges, derived using strict exclusion criteria, can aid in the diagnosis of thyroid dysfunction in pediatric populations.
• Findings suggest that the upper limit of the TSH reference range may not require reduction in children.