title: Circadian blood pressure rhythm is disturbed by nephrectomy.
abstract: We recently illustrated a close relationship between glomerular filtration rate and circadian rhythm of blood pressure (BP) in patients with chronic kidney disease. However, it remains undetermined from such cross-sectional findings which occurs first, the loss of kidney function or the lack of nocturnal BP fall. In the present study, we examined whether circadian rhythm of BP is affected by unilateral nephrectomy for kidney donation to clarify this important issue. Fifteen healthy subjects (4 men, 11 women; aged 33 to 65 years; mean age 55 +/- 2 years) who underwent unilateral nephrectomy for kidney donation were studied. Ambulatory BP was monitored for 24 h, while serum and urinary samples were collected to estimate creatinine clearance before and on the 8th day after nephrectomy. Then, changes in the night/day ratios of mean arterial BP were analyzed in relation to the decrease in 24-h creatinine clearance as a marker of glomerular filtration rate by nephrectomy. Creatinine clearance was reduced by 29% in average from 84 +/- 6 to 60 +/- 4 ml/min by nephrectomy, while 24-h mean arterial BP values were 91 +/- 3 and 94 +/- 4 mmHg (p=0.08) before and after nephrectomy. Although mean BP (daytime, nighttime or night/day ratio) was not altered significantly by nephrectomy, the decrease in creatinine clearance was positively correlated with the increase in the night/ day ratio of mean BP (r=0.61, p=0.017). The decrease in creatinine clearance was not correlated with changes in either 24-h, daytime or nighttime mean BP. Our results suggest that unilateral nephrectomy disturbs the circadian rhythm of BP as a function of renal dysfunction without affecting absolute levels of BP. Non-dipping of BP seems the consequence of the loss of renal function, rather than the cause.
authors.affiliation: Department of Transplant Surgery, Nagoya Daini Red Cross Hospital, Nagoya, Japan.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Goto
authors.forename: Kazuharu
authors.initials: K
authors.lastname: Uchida
authors.forename: Kunio
authors.initials: K
authors.lastname: Morozumi
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Ueki
authors.forename: Susumu
authors.initials: S
authors.lastname: Matsuoka
authors.forename: Akio
authors.initials: A
authors.lastname: Katayama
authors.forename: Toshihito
authors.initials: T
authors.lastname: Haba
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Tominaga
authors.forename: Michio
authors.initials: M
authors.lastname: Fukuda
authors.forename: Akimasa
authors.initials: A
authors.lastname: Nakao
authors.forename: Genjiro
authors.initials: G
authors.lastname: Kimura
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006977:Hypertension, Renal; D016030:Kidney Transplantation; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000009:adverse effects*
chemical_list: D003404:Creatinine