Table 1 Laboratory findings showing rapid onset anemia and recovery after discontinuation of phenazopyridine. Patient received 1 unit of packed red blood cells on day 17 of phenazopyridine. WBC normal range 4.0-11.0 10e3/uL, hemoglobin normal range 11.7-15.7 g/dL, hematocrit normal range 35.0-47.0%, platelet count 150-450 10e3/uL, RBC count 3.70-5.30 10e6/uL, MCV 77-100 fl, MCH 26.5-33.0 pg, MCHC 31.5-36.5 g/dL, and RDW 10.0-15.0%.