Disturbed Circadian Rhythm of Urinary Albumin Excretion in Non-Dipper Type of Essential Hypertension

Abstract

Recently, we found that the circadian rhythms of natriuresis as well as of glomerular filtration rate were disturbed similar to the blood pressure in non-dipper type of essential hypertension during intake of a high-sodium diet. In this study, we examined circadian rhythms of the urinary albumin excretion rate (AER), which is recognized as a marker of glomerular capillary hydraulic pressure, in addition to those of urinary sodium excretion and blood pressure in 27 patients with essential hypertension. The patients were maintained on relatively high (10–12 g) on low (1–3 g) sodium (NaCl) diets for 1 week. On the last day of each diet, the 24-hour blood pressure was measured every 30 min noninvasively, and during the last 3 days, urine samples were collected for determination of both daytime (07:00–21.30 h) and nighttime (21.30–07.00 h) sodium and AER variations. During the high-sodium diet, nocturnal falls in urinary sodium excretion and blood pressure were observed in dippers (n = 7), while they were not observed in non-dipper (n = 20). The nocturnal decline in AER was also observed in dippers (day: 37 ×/÷ 6 µg/min vs. night: 22 ×/÷ 5 µg/min; p < 0.02), while it was not observed in non-dippers (day: 49 ×/÷ 6 µg/min vs. night: 40 ×/÷ 8 µg/min; NS). During intake of the low-sodium diet, on the other hand, a nocturnal decline in AER was observed in both types of hypertension. Sodium restriction significantly reduced only the nighttime AER in non-dippers (p < 0.01). These findings indicate that changes in dietary sodium intake modified the circadian rhythms of both blood pressure and AER in non-dippers. Renal sodium handling may contribute to determining the circadian rhythm of blood pressure, and furthermore an elevated glomerular capillary hydraulic pressure during the night may enhance the nocturnal albumin excretion in non-dippers.

Low-Dose Losartan Therapy Reduces Proteinuria in Normotensive Patients with Immunoglobulin A Nephropathy

“…Changes in dietary sodium intake modified the circadian rhythms of both blood pressure and the urinary albumin excretion rate in non-dipper blood pressure. Renal sodium handling may contribute to determining the circadian rhythm of blood pressure, and, furthermore, an elevated glomerular capillary hydraulic pressure during the night may enhance the nocturnal albumin excretion in non-dipper blood pressure (39). There is a possibility that the nocturnal drop in blood pressure might contribute to decreased urinary protein excretion.…”

Silent Brain Infarction – A Review of Recent Observations

“…It was also reported that loss of the circadian BP rhythm in hypertensive patients could result in higher risk of cerebral and cardiovascular events (72,73). Therefore, the nocturnal BP variation and role of nocturnal BP drop in SBI was thoroughly investigated, revealing higher prevalence of SBI in non-dippers, than in dippers, both in patients with multiple or single lesions.…”

An overview of nocturia and the syndrome of nocturnal polyuria in the elderly

“…their sodium excretion does not fall with sleep), which can be addressed by dietary sodium restriction. Nishimura et al 59 observed that the normal circadian rhythm of urinary albumin excretion rate, a marker of glomerular capillary hydraulic pressure, is disturbed in non-dipping patients with hypertension. Graugaard-Jensen et al 60 reported that healthy men with nocturia have a higher mean arterial blood pressure than do those without nocturia.…”