Endocrine Abstracts

JOINT2181

Relevance: Childhood is critical for skeletal development, with peak bone mass accrual during this period. By puberty’s end, bone mass reaches 86–100% of adult levels. Thyrotoxicosis disrupts bone remodeling, causing osteoporosis, osteosclerosis, and a 10% loss per cycle, with BMD declining by up to 28%. Identifying predictors of bone metabolism impairment is essential for early diagnosis, prevention, and treatment.

Materials and Methods: This study included 97 healthy children and 146 with hyperthyroidism. Thyroid hormones, autoantibodies, osteocalcin, parathyroid hormone (PTH), vitamin D, calcium, phosphorus, and alkaline phosphatase were quantified using the Cobas e 411 Hitachi immunochemical analyzer (Hoffmann-La Roche, Switzerland). BMD was assessed via dual-energy X-ray absorptiometry (DXA) using the Stratos densitometer (Diagnostic Medical Systems, France).

Results: ROC analysis demonstrated that osteocalcin (AUC = 0.72; 95% CI: 0.52–0.91; P= 0.05), anti-TSH receptor antibodies (AUC = 0.71; 95% CI: 0.51–0.91; P = 0.05), anti-TPO antibodies (AUC = 0.70; 95% CI: 0.51–0.90; P = 0.05), b-CrossLaps (AUC = 0.70; 95% CI: 0.50–0.90; P = 0.05), and vitamin D (AUC = 0.63; 95% CI: 0.53–0.74; P = 0.01) were significant predictors of total-body BMD reduction in pediatric hyperthyroidism. Conversely, thyroid hormone levels, PTH, calcium, and alkaline phosphatase had an AUC of 0.5, aligning with the null hypothesis. Further stratification of vitamin D and osteocalcin levels in relation to BMD reductions at different DXA sites identified osteocalcin >100 ng/mL (AUC = 0.65; 95% CI: 0.55–0.74; P = 0.05) and vitamin D <20 ng/mL (AUC = 0.70; 95% CI: 0.59–0.80; P = 0.05) as reliable markers. These were "good" predictors for total-body and femoral BMD loss and "satisfactory" for lumbar spine BMD. The strongest predictor of vitamin D deficiency-related outcomes in pediatric hyperthyroidism was anti-TSH receptor antibodies (AUC=0.84; 95% CI: 0.68–0.99; P< 0.001).

Conclusions: ROC analysis in pediatric hyperthyroidism highlights the role of autoimmune activity and vitamin D deficiency in bone metabolism dysregulation. Autoimmune mechanisms may accelerate bone demineralization, underscoring the need for targeted diagnostic and therapeutic strategies.