Abstract
Hematocrit (Hct) changes during mental stress were studied in 21 patients with mild hypertension. A 10min arithmetic stress test increased blood pressure from 129±2/80±2mm Hg (mean±SEM) to 167±5/98±3mm Hg, and heart rate from 64±2 to 81±3 (p<0.001). Concomitantly, a significant (p<0.001) increase in Hct was observed (from 41.5±0.7% to 42.2±0.8%), and increments of Hct (-0.1% to 2.2%) were significantly (r=0.61, p<0.01) correlated with those of systolic blood pressure. Plasma levels of norepinephrine (NE), epinephrine (E) and atrial natriuretic peptide (ANP) also showed a significant increase after mental stress. All these changes disappeared after a 60min recovery period. The results suggest that mental stress increases Hct promptly, which may be due to concomitant increases in plasma NE, E and ANP levels. Hct elevation resulting from mental stress may be clinically relevant, at least, in hypertensive patients who are at risk of occlusive vascular diseases.
