Establishment of reference intervals for bone markers in children and adolescents

Objectives: To determine age and gender specific reference intervals for bone markers. Design and methods: Morning blood samples were collected after overnight fast from 356 healthy children (6 to 18 year-old) for the determination of bone marker levels, PTH and vitamin D-3. Multiple regression analysis was done to assess the effect of factors that could influence the bone marker levels: the central 95% reference interval and their 90% Cl were calculated. Results: After excluding samples when BMI-z scores were <-2 or >+2, both vitamin D-3 and FTH levels were abnormal and from children who used steroids the remainder were partitioned using Tanner stage based chronological age. As expected the reference intervals show a significant variation with age and gender. All the bone marker levels, except total alkaline phosphatase, were significantly higher in puberty with vitamin D-3 > 75 nmol/L. Conclusion: Vitamin D status, age and gender are important for establishing reference intervals of bone markers in healthy children. (C) 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.