THU231 Thyroid Function And Childhood Bone Mineral Density: Abnormal Thyrotropin Concentration May Be Another Predictor Of Pediatric Low Bone Mass

Disclosure: M. Ahn: None. Backgrounds: Thyroid hormone (TH) whose synthesis and secretion are mainly regulated by thyrotropin (TSH) play a critical role in the metabolism, growth, and development of human body. While TH is responsible for normal growth and differentiation of various organs, bone is known to be one of the major endocrine organs affected by the regulation of TH. Low bone mass or osteoporosis of child and adolescents can occur in numerous chronic conditions, however the influence of abnormal TH and TSH on low bone mineral density (BMD) of children and adolescents remains controversial. Investigating the effect of excessive or deficient TH and TSH on childhood BMD may unveil a better understanding of uncertain role of thyroid function in bone density of pediatric population. Objective: To elucidate the connection between thyroid function and childhood low bone mass. Methods: Serum T3, FT4 and TSH of 619 children aged between 10 to 18 years and previously diagnosed with hemato-oncologic, rheumatoid, gastrointestinal, endocrine conditions whose treatment was completed were assessed simultaneously with mineral density of lumbar spine and femur measured by dual energy x-ray absorptiometry. Serum T3, FT4, and TSH were subcategorized as either high/normal/low or normal/abnormal group with respect to age-matched reference range, then LSBMD data were compared. Comparison, correlation and regression analyses were performed to examine the association between the abnormality of thyroid function and low BMD. Results: Mean LSBMD z-scores of 619 children and adolescents were 0.49±1.28 and those who were less than -1.0 accounted for 37.7 % while serum T3, FT4, and TSH levels were 1.25±0.29 ng/mL, 1.28±0.19 ng/dL, and 2.76±1.87 µU/mL, respectively. Both lumbar and femoral BMD z-scores were not significantly different in between subjects with either abnormal or normal serum T3 and FT4, however were lower in children with abnormal serum TSH. LSBMD (g/cm(2)) was negatively correlated with serum T3 whereas its z-scores showed no correlation with any of serum T3, FT4 and TSH. In linear regression, BMI z-scores were positively associated whereas serum T3, FT4, TSH were not directly associated with LSMBD z-scores. When the abnormality of T3, FT4, and TSH was considered as determinants for decreasing LSBMD z-scores, TSH abnormality was a significant risk factor having highest odds ratio as LSBMD z-scores decreased. Conclusion: Although serum T3, FT4, and TSH did not show a direct correlation with childhood LSBMD z-scores, abnormal TSH concentration could predict low LSBMD z-scores, therefore indicate low bone mass of children with various underlying conditions. Presentation: Thursday, June 15, 2023