In contrast with the cross-sectional analysis by Oliva-Damaso et al.,[16] paricalcitol had a robustly null effect on the plasma concentration of ADMA and SDMA and extensive interaction analyses showed no modification of the effect of paricalcitol on these methylargines in relationship with demographic factors (age, gender) and the main biomarkers of the mineral bone disorder in CKD including calcium, phosphate, 25-OH vitamin D, 1,25-(OH)2 vitamin D, PTH and FGF23. The gene discussed is FGF23; the disease is chronic kidney disease.