Exposure to hyperoxia in diving and hyperbaric medicine--effects on blood cell counts and serum ferritin.

A reduction in hemoglobin concentration has been consistently reported after deep saturation dives, whereas reductions in thrombocyte counts and changes in biochemical parameters specific for liver function have been reported after some dives. In this study the contribution of exposure to hyperoxia to these changes were studied. Hemoglobin concentration, blood cell counts, serum ferritin, and biochemical parameters specific for liver damage were measured before and after a shallow 28-day saturation dive to a pressure of 250 kPa with the same hyperoxic exposure (40-50 kPa) as in a deep saturation dive in eight male divers. The same parameters were measured before, during, and after a standard 21-day hyperbaric oxygen (HBO2) treatment series in a selected group of 16 patients (8 male). There were significant reductions in hemoglobin concentrations of 3.8 +/- 4.7% (P = 0.023) and 10.2 +/- 5.3% (P = 0.003) after the HBO2 treatment series and dive, respectively, accompanied with reductions in red cell counts, reticulocyte counts, and hematocrit. There was an increase in ferritin concentrations of 29 +/- 21% (P = 0.002) and 107 +/- 43% (P < 0.001). In contrast to some deep dives, there were no changes in thrombocyte counts or biochemical parameters specific for liver damage. Exposure to hyperoxia contributes significantly to reduced hemoglobin and increased ferritin concentrations after saturation dives. The changes may reflect a shift of iron from synthesis of hemoglobin in the bone marrow to storage in macrophages caused by a downregulation of hemoglobin synthesis, or an increased oxidative stress. The changes are too small to be of clinical significance with respect to diving and HBO2 treatment.