Association of serum ferritin with bone turnover markers and bone mineral density in children and adolescents: Finding from NHANES 1999-2002.

ObjectiveThe effect of iron on bone metabolism in children and adolescents remains largely unknown. This study examined the association of serum ferritin with bone mineral density and bone turnover markers in this population.MethodsWe used data from the 1999-2002 National Health and Nutrition Examination Survey, including serum ferritin, lumbar bone mineral density, bone turnover markers (serum bone alkaline phosphatase and urinary N-telopeptides), and relevant covariates. Weighted multivariate linear regression analyses and smooth curve fitting were conducted to investigate the association of ferritin with bone mineral density and bone turnover markers. Additionally, subgroup and threshold effect analyses were also performed.ResultsA total of 1527 participants were included in the study. Ferritin was positively correlated with bone mineral density only in the unadjusted model. In the overall population, all models showed negative correlations between ferritin and serum bone alkaline phosphatase and urinary N-telopeptides. In subgroup analyses, these associations remained significant in males but not in females. Smooth curve fitting demonstrated nonlinear relationships between ferritin and serum bone alkaline phosphatase and urinary N-telopeptides, with inflection points identified at 41 ng/mL and 16 ng/mL, respectively.ConclusionsOur study demonstrated an inverse, nonlinear association between ferritin and bone turnover markers, primarily observed in males. The identified inflection points suggest a threshold effect, highlighting the importance of maintaining adequate iron levels for bone health, particularly in male children and adolescents.