Explanation for apparent hypoxemia associated with extreme leukocytosis: leukocytic oxygen consumption.

We investigated the hypoxemia associated with extreme leukocytosis in leukemic patients. In vitro experiments showed that the rate of decrease in the partial pressure of oxygen in the blood samples from such patients was proportional to the white cell count. In the presence of normal white cell count no drop in PO2 was observed. We conclude that a low arterial oxygen tension in the presence of extreme leukocytosis reflects oxygen consumption by leukocytes rather than true hypoxemia. Both normal as well as leukemic leukocytes appear to exhibit this phenomenon.