Thyroid Stimulating Hormone, T۳ and T۴ Population-based Reference Range and Children Prevalence of Thyroid Dysfunction: First Report from South of Iran

Background & Objective: The TSH reference range's validity affects the thyroid dysfunction diagnosis. The primary objective of this study is to determine the reference range, which is established according to age and region.Methods: The data were collected retrospectively from people over the age of one who visited Motahari Clinic for routine health checkups between August ۲۰۱۷ and October ۲۰۱۹. TSH, T۴, T۳, personal drug usage, and thyroid history were collected. After excluding subjects with thyroid diseases and outliers, a list of ۱۳۹۲ participants was analyzed. Hormone intervals of men and women ≥۱ year old have been determined using the non-parametric method.Results: The non-disease subjects' TSH, T۳, and T۴ reference ranges were ۰.۶۴ to ۵.۹۴ lU/mL, ۰.۹۱ to ۲.۴۷ ng/dL, and ۵.۵۳ to ۱۲.۴۸ g/dL, respectively. According to this range, total thyroid dysfunction prevalence in our study in children was ۸.۹۴%. There was no significant difference between TSH, T۴ level, and sex in the non-disease population (P=۰.۴۶ and ۰.۱۳, respectively), but there was a statistical difference between sex and T۳ (P =۰.۰۳). Our study also illustrates that for subjects under ۱۸ years old and above it, hormones (TSH, T۳, T۴) concentration is statistically different (P≤۰.۰۰۱).Conclusion: We found a statistical difference between hormone values after and before age ۱۸ (P=≤۰.۰۱); therefore, it is not appropriate to use the same reference range for children under age ۱۸ and adults. There was male dominance in the population ۱-۱۸ years old. 

Keywords:

Iran , range , reference , Reference range , TSH