[Polycythemia vera and 2,3-diphosphoglycerate deficiency. Apropos of 2 cases]

Two cases of mistaken diagnosis of polycythemia vera leading to useless or dangerous treatments exemplify the old saying "primum non nocere". Absolute polycythemia which lacks both the specific characteristics of polycythemia vera and lacks both the specific characteristics of polycythemia vera and any tumoral etiology (particularly renal) but is accompanied with normal arterial oxygen saturation should suggest the possibility of an anomalous hemoglobin with increased affinity for oxygen. Two alternative mechanisms may be present: anomalous hemoglobins due to the substitution of an amino acid or, as in the two reported cases, a deficit in intraerythrocytic 2,3 diphosphoglyceride. In both cases, polycyhthemia is compensative and does not warrant therapy.