Diarrhea induced by high doses of nicotinamide in dialysis patients.

To the Editor: Takahashi et al. 1 have recently described the effect of nicotinamide for controlling hyperphosphatemia in dialysis patients. However, Rottembourg et al. 2 reported thrombocytopenia in the same setting. We have started a prospective, open-label trial to study the efficiency and safety of nicotinamide in our hemodialysis patients with resistant hyperphosphatemia. Unlike Takahashi, we did not stop other phosphate binders. Six patients have already been included. Two patients were intolerant to sevelamer and thus only treated with calcium carbonate. The other four patients received a combined therapy. Five patients developed diarrhea during the study. In two of them, it was so important that nicotinamide had to be stopped. After discontinuing nicotinamide, diarrhea disappeared. In the three other patients, diarrhea improved with decreasing the dose of nicotinamide. The diarrhea started at a mean dose of 1050 ± 447 mg. We observed a significant decrease in phosphatemia while on treatment (from 85 ± 8.7 to 54 ± 12.1mg/l; P = 0.0048 for the repeated measure analysis of variance), but no effect on platelet count (from 260.167 ± 40.435 to 281.167 ± 51.503; P = 0.33).