Seasonal hematocrit variation and health risks in the adult population of Kinshasa, Democratic Republic of Congo.

Hematocrit (Hct) as an indicator of blood viscosity and mean arterial blood pressure (MAP) were assessed according to the season in adult participants of health screenings conducted throughout Kinshasa, Democratic Republic of Congo. Data was collected at the end of summer (April) and the end of winter (August) and identified by gender. Male Hcts in August were significantly higher (P < 0.0001) than in April (48.3% +/- 4.2% and 45.7% +/- 2.3%, respectively) while male MAP (85.0 +/- 8.4 mm Hg) was identical to that recorded in April (85.4 +/- 7.7 mm Hg). August female Hcts (41.4% +/- 3.1%) were statistically higher than those recorded in April (39.6% +/- 1.9%, P = 0.001), MAP being 82.3 +/- 7.3 vs 87.9 +/- 6.6 mm Hg, respectively (P = 0.0001). Systolic and diastolic blood pressures, heart rate, body mass indices, ages, and personal and familial medical histories of the August and April groups were not significantly different. This study offers further support for the assertion that the relationship between blood viscosity and pressure of a healthy population shows that increased Hct, and therefore increased blood viscosity is associated with lowered MAP, and presumably peripheral vascular resistance.