Relationship of blood pressure levels to height, weight and sodium and potassium excretion in Spanish children.

To study the distribution of blood pressure (BP) in children we measured the BP of 1928 children (aged 6-14 years) living in Torrejón de Ardoz, Spain. Of these, 441 children, representative of all ages, supplied a 24-h urine sample from which sodium and potassium were determined. There was a progressive rise in systolic BP of 1.8 mmHg and in diastolic BP of 0.8 mmHg per year of age. The correlations between BP, height and weight were positive and almost always statistically significant. Sodium excretion varied from 159 +/- 30 mmol/day at 6-7 years to 170 +/- 40 mmol/day at 13-14 years. There was a positive correlation between BP and sodium excretion which was statistically significant for diastolic BP in girls aged 6-7 years (P < 0.01) and for systolic BP in boys aged 10-12 (P < 0.05) and 13-14 (P < 0.01) years.