Flucytosine interference with serum creatinine determinations.

A patient receiving intravenous amphotericin B and oral flucytosine was found to have falsely elevated serum creatinine values. Flucytosine has been reported to interfere with serum creatinine determinations when measured by the Kodak Ektachem-700 analyzer but not when the Jaffe reaction is employed. Serum creatinine values were determined by the two methods on six serum samples obtained from this patient at various times throughout her hospitalization. Flucytosine can cause clinically significant false elevations in serum creatinine when measured by the Kodak Ektachem-700 analyzer.