ESPE Abstracts

Background: Osteoprotegerin (OPG) is a cytokine of the tumour necrosis factor receptor family, expressed in various cells types of the body including osteoblasts and endothelial cells. It acts as a soluble decoy receptor of RANK ligand preventing stimulation of osteoclastogenesis. In adults, subclinical hypothyroidism (SH) has been associated with cardiovascular complications. Furthermore several studies have linked OPG levels to increased cardiovascular risk.

Objective and hypotheses: In the present study we investigated the levels of OPG and other indices of bone metabolism such as tartrate-resistant acid phosphatase (TRAP) and bone alkaline phosphatase (BAP) in children and adolescents with SH.

Method: The present study included 129 children and adolescents with SH (TSH between 5 μIU/l and 10 μIU/l with fT₄ levels within normal range) and 346 healthy controls. In all subjects, age, gender and BMI were recorded and TSH, fT₄, OPG, TRAP and BAP were measured. Regression analysis adjusted for age and BMI after appropriate log transformations was used and statistical significance was indicated with p value <0.05.

Results: All 475 subjects (215 males) had mean age 8.4±3.62 years old. Age and BMI z-score were no statistically different between SH and control group. In children with SH OPG and TRAP levels were negatively correlated to the serum fT₄ levels with r=−0.22 (P=0.015) and r=−0.16 (P=0.002) respectively. No correlation was found between BAP and fT₄. The above associations were not observed in the control group.

Conclusion: OPG and bone TRAP levels in children and adolescents with SH are negatively correlated with fT₄. Considering the probable effects of increased OPG in the vascular homeostasis, further research is needed to establish the role of childhood SH in the long-term cardiovascular risk.