Cubic spline smoothed population mean levels (with 95% confidence intervals) in ln(FGF-23) (red), ln(PTH) (green), phosphate (blue), and calcium (orange) levels prior to ESRD transition. Shaded areas represent 95% confidence intervals. The table below the plot depicts the number of participants with available measurements of FGF-23, PTH, phosphate, and calcium by years prior to ESRD transition. Repeated measures values are shown as median (interquartile range) for FGF-23 and PTH and mean ± standard deviation for phosphate and calcium.