FP803EFFECTS OF NICOTINAMIDE AND LANTHANUM CARBONATE ON SERUM PHOSPHATE AND FGF23 CONCENTRATIONS IN CHRONIC KIDNEY DISEASE: PRIMARY RESULTS OF THE COMBINE TRIAL. (28th May 2018) - Ix, Joachim; Isakova, Tamara; Larive, Brett; Raphael, Kalani; Raj, Dominic; Cheung, Alfred; Sprague, Stuart; Fried, Linda; Gassman, Jennifer; Middleton, John; Flessner, Michael; Block, Geoffrey; et al.