Ferric citrate treatment increased mean TSAT from 22 % 7 % ( SD ) to 32 % 14 % and reduced serum phosphate levels from 4.5 0.6 to 3.9 0.6 mg/dL , while placebo exerted no effect on TSAT ( 21 % 8 % to 20 % 8 % ) and less effect on serum phosphate level ( 4.7 0.6 to 4.4 0.8 mg/dL ; between-group P < 0.001 for each ) .