The children reference range of thyroid hormones in Northern Iran

Area of Science:

• Pediatric Endocrinology
• Clinical Biochemistry
• Thyroid Research

Background:

• Hypothyroidism in children can lead to significant mental and growth abnormalities.
• Establishing accurate reference ranges for thyroid hormones is crucial for diagnosing and managing pediatric thyroid disorders.
• Previous studies have indicated potential regional variations in thyroid hormone levels.

Purpose of the Study:

• To determine the reference ranges for thyroid stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3) in children residing in Northern Iran.
• To investigate potential correlations between thyroid hormone levels, age, and sex within the pediatric population.
• To assess the necessity of region-specific reference ranges for thyroid function tests in clinical practice.

Main Methods:

• A random sample of children across four age groups up to 21 years was selected from a diagnostic laboratory in Gorgan, Northern Iran.
• Thyroid hormone levels (TSH, T4, T3) were measured using Radioimmunoassay (RIA) techniques.
• Statistical analysis was performed to determine mean concentrations, identify sex-based differences, and explore age-related correlations.

Main Results:

• Mean concentrations for T4, T3, and TSH were reported across the four age groups.
• The mean values for T3 and TSH were observed to be higher in females, while T4 was slightly higher in males.
• An inverse correlation between age and T4 levels was noted across all age groups.

Conclusions:

• The established reference ranges for TSH, T4, and T3 in this Northern Iranian pediatric cohort differ from universal standards.
• Significant variations in lower and upper limits of reference ranges were observed across age groups and between sexes.
• The findings underscore the critical need for establishing region-specific reference ranges for thyroid hormones to ensure accurate diagnosis and effective clinical management in pediatric hypothyroidism.