Nocturia and Circadian Blood Pressure Profile in Healthy Elderly Male Volunteers

Abstract

Nocturia is attributed to nocturnal polyuria and/or decreased functional bladder capacity. In this study we elucidated the mechanisms behind circadian fluid regulation and the occurrence of nocturia in healthy elderly males, specifically to determine the role of urine output and regulating hormones, blood pressure, and average voided volumes. A total of 18 males 55 to 73 years old (mean age 61.1) were included in the study. Voiding habits were assessed by completion of a 7-day frequency volume chart recording all fluid intake and voiding. The subjects subsequently underwent inpatient circadian studies measuring the diurnal rhythm of blood pressure, vasopressin, atrial natriuretic peptide, angiotensin II, aldosterone and urine volume. Of the nightly home recordings 25% showed nocturia, characterized by a higher 24-hour and nighttime urine volume. During the inpatient studies 12 of the 18 participants experienced a nocturnal void. Nocturia nights were characterized by significantly decreased day-to-night ratios in urine output and a higher nighttime mean arterial blood pressure. A circadian variation in plasma arginine vasopressin was seen only in the group without nocturia. The other hormones revealed a circadian rhythm similar in the 2 groups. In healthy males with occasional nocturia, the occurrence of nocturia seems to be associated with a blunting of the circadian rhythm of diuresis and increased arterial blood pressures during the night. These findings may implicate a role for a baroregulatory related mechanism in nocturia.