Serum free 1,25-dihydroxy-vitamin D is more closely associated with fibroblast growth factor 23 than other vitamin D forms in chronic dialysis patients

The relationship between FGF-23 and vitamin D is stronger using free forms of 25-OH-D and 1,25-(OH)2-D. Subsequent studies aiming at MBD should consider including free 25-OH-D and 1,25-(OH)2-D in the analysis.