LETTER
Chronic Severe Hemolytic Anemia from Phenazopyridine
E. Peter Gabor
15 January 1995 | Volume 122 Issue 2 | Pages 156-157
TO THE EDITOR:
Thomas and colleagues [1] recently described chronic severe hemolytic anemia related to phenazopyridine. We also previously reported [2] the potent oxidative hemolytic effect of phenazopyridine (Pyridium).
Our patient with a normal glucose-6-phosphate dehydrogenase level developed severe Heinz-body hemolytic anemia and developed sulfhemoglobinemia after prolonged treatment with phenazopyridine. The patient had a nadir hemoglobin level of 7.3 g/dL a reticulocyte count of 13%, and Heinz bodies in 20% of her erythrocytes.
In vitro studies with erythrocytes deficient in glucose-6-phosphate dehydrogenase showed that phenazopyridine has 50% of the oxidant capacity of the benchmark (standard) compound acetylphenyl hydrazine [2]. It is useful to be aware of this adverse effect because phenazopyridine is frequently prescribed for various nonspecific urinary symptoms.
1. Thomas RJ, Doddabele S, Karnad AB. Chronic severe hemolytic anemia related to surrepetitious phenazopyridine abuse. Ann Intern Med. 1994; 121:308.
2. Gabor EP, Lowenstein L, De Leeuw NK. Hemolytic anemia induced by Phenylazo-Diamino-Pyridine (Pyridium). Can Med Assoc J. 1964; 91:756-9.
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