Circannual rhythms of systolic and diastolic blood pressure in relation to plasma aldosterone and urinary norepinephrine in elderly subjects and in children.

Sixty six elderly men and 87 elderly women 77 +/- 8 (S.D.) years of age were studied in 285 profiles consisting of measurements of systolic and diastolic blood pressure obtained at 4 hour intervals during the waking hours of the subjects for 2 or 7 days and (among others) plasma aldosterone and urinary norepinephrine determinations collected in six samples at 4 hour intervals during one 24-hour span. The profiles were spread through all four seasons. The circadian means were calculated for each profile by the single cosinor method and the circannual variations were analyzed by the Bingham test and analysis of variance. A circannual rhythm of the systolic and the diastolic blood pressure was found with a peak systolic pressure in spring and peak diastolic pressure in summer. A circannual rhythm in urinary norepinephrine was statistically significant only in the women with a peak in winter, out of phase with the circannual rhythm in blood pressure. In plasma aldosterone, the highest values were found during fall and winter with statistical significance reached at the p less than .05 level in the women only. In contrast to the elderly subjects, 87 boys and 107 girls 11 +/- 1.5 (S.D.) years of age studied by the same methodology over one 24-hour span each spread throughout the four seasons showed a circannual rhythm in systolic and diastolic blood pressure and in norepinephrine excretion with a peak during winter. A circannual rhythm of the circadian mesor of the plasma aldosterone concentration was found in the children with highest values in fall and lowest values in spring (when the blood pressure values also were lowest). With all qualifications in mind about possible causal relations between rhythms showing a coincidence or a difference in phase, it appears that there are certain differences in the circannual time structure of cardiovascular and related endocrine functions between children and elderly subjects which may be of clinical importance.