The Response of Free Erythrocyte Protoporphyrin to Pyridoxine Therapy in a Patient with Sideroachrestic (Sideroblastic) Anemia

Studies of a patient with acquired sideroachrestic anemia and metastatic carcinoma of the prostate are presented. Although the administration of pyridoxine did not elicit a hematologic response, the administration of this vitamin was associated with a remarkable accumulation of protoporphyrin within the erythrocytes. It is suggested that there were two defects in the hemoglobin biosynthetic pathway: impaired incorporation of protoporphyrin into hemoglobin and defective delta-aminolevulinic acid synthesis. Pyridoxine had no effect on the former hut partially corrected the latter.