title: Nyctohemeral rhythm of plasma renin activity and plasma aldosterone in children.
abstract: Circadian rhythms of plasma renin activity (PRA) and plasma aldosterone (PA) were studied in eight healthy children, 7 to 15 years old. Blood samples were obtained at 7:00 AM, 10:00 AM, 1:00 PM, 4:00 PM, 5:00 PM, 8.00 PM, and midnight on day 1 and 4:00 AM and 7:00 AM on day 2. Children had normal activity during this test. Intra- and interindividual changes were noted in PRA in plasma taken in the upright position. Mean PRA values for samples taken in the upright position were maximal at 1:00 PM (7 ng/ml/hr) and minimal at 5:00 PM (4.1 ng/ml/hr). Mean PRA in the supine position was maximal at 4:00 AM on day 2 (5.6 ng/ml/hr), and its rise was statistically significant compared with the mean PRA at 7:00 AM on the same day (3.9 ng/ml/hr). Plasma aldosterone varied without any definite pattern. No correlation was found between PRA and PA and 24-hr urinary sodium excretion.
mesh_terms: D000293:Adolescent; D000450:Aldosterone / Q000097:blood*; D002648:Child; D002940:Circadian Rhythm; D006801:Humans; D009318:Natriuresis; D011187:Posture; D012083:Renin / Q000097:blood*; D012084:Renin-Angiotensin System
chemical_list: D000450:Aldosterone; D012083:Renin