Fig. 2

B Box plots of serum P1NP concentration by age and gender in patients under 20 years; b Cubic polynomial curves of serum P1NP concentration by age and gender in patients under 20 years; c Box plots of serum β-CTx concentration by age and gender in patients under 20 years; d Cubic polynomial curves of serum β-CTx concentration by age and gender in patients under 20 years; e Box plots of serum Ca concentration by age and gender in patients under 20 years; f Cubic polynomial curves of serum Ca concentration by age and gender in patients under 20 years; g Box plots of serum P concentration by age and gender in patients under 20 years; h Cubic polynomial curves of serum P concentration by age and gender in patients under 20 years; i Box plots of serum 25(OH)D concentration by age and gender in patients under 20 years; j Cubic polynomial curves of serum 25(OH)D concentration by age and gender in patients under 20 years; k Box plots of serum ALP concentration by age and gender in patients under 20 years; l Cubic polynomial curves of serum ALP concentration by age and gender in patients under 20 years; m Box plots of serum PTH concentration by age and gender in patients under 20 years; n Exponential curve of serum PTH concentration by age in female patients under 20 years; p < 0.05 as assessed by Regression analysis