CAMP and peritonitis: Plasma levels of FGF23 correlated strongly with the FGF23 in dialysate effluents (Figure S2 in S2 File), but there was no correlation between FGF23 and either its known target, CYP27B1, or immune markers such as HAMP and CAMP. This may be due to the relatively low levels of CYP27B1 and CAMP expression in PD cells from non-infected patients, and it will be interesting in future studies to assess the possible impact of FGF23 on vitamin D-mediated immune responses in patients with peritonitis.