Rusty peritoneal dialysis fluid after intravenous administration of iron dextran.
Rusty-colored peritoneal dialysate fluid was observed after intravenous administration of iron dextran to a patient with peritonitis being treated with vancomycin and rifampicin. The discoloration gradually cleared over a 24-hour period. Analysis of the fluid demonstrated that the discoloration could not be explained by the presence of erythrocytes or free hemoglobin. Iron (52 micrograms/dL) was detected in the fluid and decreased to undetectable levels as the discoloration cleared. Addition of iron dextran to an unused bag of peritoneal dialysis fluid to achieve an iron concentration of 52 micrograms/dL resulted in no discoloration. Addition of rifampicin at a clinically relevant serum concentration (10 micrograms/dL) to a different unused bag caused a light orange discoloration. Addition of iron dextran and rifampicin simultaneously in the concentrations mentioned to an unused bag caused a rusty discoloration almost as dark as that observed in our patient. We postulate, therefore, that a combination of iron and rifampicin caused the marked discoloration of our patient's peritoneal effluent.