Altitude and blood pressure in children.

People living at high altitude are generally observed to have lower blood pressure than those residing at sea level. To investigate whether low pO2 or low body weight accounts for this, blood pressure, weight, height and pulse rate were measured in 847 Peruvian children residing at 3500 m and compared to previously collected data in 3924 Dutch children living at sea level. In the two study populations the same protocol for measurement of blood pressure was used by observers who showed no systematic differences in average blood pressure readings during training sessions. Systolic as well as diastolic blood pressure was found to increase with age in both Peruvian and Dutch children. Systolic blood pressure by age was 5-10 mmHg lower in Peruvian boys and girls than in their Dutch counterparts. However, virtually no differences in systolic blood pressure, and to a lesser extent diastolic blood pressure, by body weight or height between Peruvian and Dutch subjects were found. These findings are in agreement with the hypothesis that differences in body weight, rather than in pO2, explain most of the observed differences in blood pressure between children of the same age living at different altitudes.