Enhanced sodium sensitivity and disturbed circadian rhythm of blood pressure in essential hypertension.
OBJECTIVE
To assess whether an association between sodium-sensitive hypertension and metabolic syndrome exists; and whether, in patients with metabolic syndrome, the nocturnal fall of blood pressure decreases and salt restriction affects the circadian blood pressure rhythm.


METHODS
Japanese patients with essential hypertension, who were treated without any antihypertensive agent, were maintained on a high-sodium diet and a low-sodium diet for 1 week each. On the last day of each diet, the 24-h blood pressures were measured. A diagnosis of metabolic syndrome was made according to the International Diabetes Foundation definition


RESULTS
Among the 56 patients with essential hypertension, 15 patients were complicated with metabolic syndrome while 41 patients were not. The nocturnal blood pressure fall was significant in patients without metabolic syndrome, while it was not so in patients with metabolic syndrome. Only in patients with metabolic syndrome was the nocturnal blood pressure fall enhanced by sodium restriction. The prevalence of sodium-sensitive hypertension in patients with metabolic syndrome was significantly higher than in those without metabolic syndrome (70.6 versus 36.0%, respectively; P = 0.017). A multiple logistic regression analysis revealed central obesity to be an independent risk factor for sodium-sensitive hypertension (odds ratio, 1.41; 95% confidence interval, 1.04-1.91).


CONCLUSIONS
In patients with essential hypertension, an inter-relationship exists among metabolic syndrome, enhanced sodium sensitivity of the blood pressure and non-dipping. The elevated risk of cardiovascular diseases in patients with metabolic syndrome may be related to sodium-sensitive hypertension and non-dipping.
Uzu
Takashi
T
Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan. takuzu@belle.shiga-med.ac.jp
Kimura
Genjiro
G
Yamauchi
Atsushi
A
Kanasaki
Masami
M
Isshiki
Keiji
K
Araki
Shin-ichi
S
Sugiomoto
Toshiro
T
Nishio
Yoshihiko
Y
Maegawa
Hiroshi
H
Koya
Daisuke
D
Haneda
Masakazu
M
Kashiwagi
Atsunori
A
D000328:Adult; D000704:Analysis of Variance; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects*; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000187:drug effects*; D015986:Confounding Factors, Epidemiologic; D004039:Diet, Sodium-Restricted; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D024821:Metabolic Syndrome / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology; D008875:Middle Aged; D009318:Natriuresis / Q000187:drug effects; D009765:Obesity / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology; D015995:Prevalence; D012307:Risk Factors; D012982:Sodium, Dietary / Q000008:administration & dosage*
D000959:Antihypertensive Agents; D012982:Sodium, Dietary