Development of Neutrophilia by serially increasing doses of dexamethasone

Dexamethasone (4-8 mg/m2 body surface area) was given orally or intravenously to six normal volunteers. The maximum neutrophil count occurred 4-6 h after oral or intravenous administration of dexamethasone and was due almost entirely to an increase in mature neutrophils; concomitantly there was a lymphocytopenia. A second rise in the neutrophil count occurred 24 h after oral ingestion of dexamethasone, coinciding with a lymphocytosis. Neutrophil alkaline phosphatase (NAP) activity during development fell as the neutrophil count rose. Other haematological values were unchanged except for small increments in erythrocyte sedimentation rate (ESR). Sodium concentration in serum and urine remained normal but urinary potassium excretion and urine volume increased after the intravenous dose. There was a direct relationship between plasma concentration of dexamethasone and the rise in neutrophil count following intravenous but not oral administration. The concentration of dexamethasone in plasma fell to half its peak value in 2-6 h. Dexamethasone-induced neutrophilia was similar to that induced by other corticosteroids. Dexamethasone in a dose of 6 mg/m2 produced minimal discomfort while inducing an adequate neutrophilia in the volunteers.