Background and aims Urinary levels of N-telopeptide (NTx) have been reported to be a sensitive and specific marker of bone resorption. This cross-sectional study determined the urinary levels of NTx among healthy children living in Calgary and explored their relationship with age, sex and vitamin D status.
Methods We included healthy children 2 to 13 years of age who presented to the Alberta Children’s Hospital for elective surgery during a 12-month period. Data including the child’s weight, height, age, gender, ethnicity, dietary intake, vitamin intake, and physical activity were collected. Urinary NTx levels were measured with a commercially (Wampole Laboratories, Princeton) available competitive-inhibition enzyme-linked immunosorbent assay.
Results Urinary NTx levels were available for 968 out of 1862 participants, of whom 605 (62.5%) were boys. The mean urinary NTx/Creatinine ratio was 605.4 nmol/mmol (SD 264.8, range 200–2985.1). We found that mean urinary NTx/creatinine excretion was higher in the younger children (2–5 years) compared to subsequent ages. There was no significant difference in urinary NTx levels between children with suboptimal vitamin D status (serum 25-hydroxyvitamin D <80 nmol/L) compared to those with optimal vitamin D status.
Conclusions Higher urinary NTx levels were measured in our healthy paediatric participants compared to what has been reported in healthy adults. In healthy children, urinary NTx levels may not be a useful marker of increased bone turnover in face of suboptimal vitamin D status. Future research is needed to determine the effect of suboptimal vitamin D status on bone health in children.