Establishment of reference intervals for bone markers in children and adolescents

ObjectivesTo determine age and gender specific reference intervals for bone markers.Design and methodsMorning 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 D3. 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% CI were calculated.ResultsAfter excluding samples when BMI-z —scores were <−2 or >+2, both vitamin D3 and PTH 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 D3 > 75 nmol/L.ConclusionVitamin D status, age and gender are important for establishing reference intervals of bone markers in healthy children.