Cardiovascular and Hematologic Responses to Phlebotomy in Blood Donors

Cortisol and heart rate changes in first- and fourth-time donors

It is well-known that during blood donation some subjects experience mild, moderate, or severe stress reactions. The frequency of these reactions is higher in first-time donors than in experienced ones. However, hormonal variations might nevertheless be present in subjects who show no clinical reaction. Cortisol is the hormone classically involved in response to stress. The aim of this study was to evaluate cortisol behavior in blood donors who did not manifest clinical reaction. Cortisol was studied before and after the first and fourth blood donation in 20 blood donors, aged 25-45 years. Blood pressure and heart rate were also evaluated. Plasma cortisol concentrations decreased during the first (from 202.6 +/- 9.2 ng/ml at -15 min, to 147.5 +/- 8.0 ng/ml, at +30 min; p < 0.001), but not during the fourth (142.5 +/- 7 ng/ml vs. 153.0 +/- 10.1 ng/ml) blood donation; blood pressure remained stable throughout donations, while the heart rate significantly decreased (from 78 to 68 beats/min; p < 0.001) only during the first experience. The increased cortisol levels observed before the first donation are apparently due to emotional components, since they were not observed in experienced donors. We may conclude that blood donation per se is not a stressful event and that moderate stress, as suggested by the increased cortisol levels and heart rate at the first donation, is secondary to emotional rather than to physical factors and occurs during a never-experienced-before event.