Circadian Rhythm of Blood Pressure and Urinary Sodium Excretion in Patients With Metabolic Syndrome

Salt-sensitive hypertension is known as most severe, treatment resistance course, with high incidence of fatal complications. This type of hypertension is more prevalent among metabolic syndrome (MS) patients. Inverted circadian rhythm so called “non-dipper" pattern carries a significant risk of cardiovascular morbidity and mortality. The aim of the study was to determine the relationship between the circadian rhythm of blood pressure, salt-sensitive hypertension and MS. We investigated 92 ethnically Georgian middle-aged patients of stage I essential hypertension (JNC VIII). Anthropometry, blood pressure monitoring, and 24 hr urinary sodium excretion were performed. All subjects were tested for salt-sensitivity. Blood pressure circadian rhythm was assessed by 24 hr ambulatory blood pressure monitoring with 1-hour intervals. Circadian rhythm of renal sodium excretion was assessed by comparison of daytime and nocturnal natriuresis and calculating their ratio. MS was classified as recommended by the International Diabetes Federation - IDF9. Our results have shown that virtually all hypertensive patients of Georgian ethnicity consumed very high amount of sodium chloride. The study revealed high incidence of salt-sensitive hypertension among patients with metabolic syndrome. High salt intake attenuated the circadian rhythm of blood pressure in SS patients; salt-sensitive hypertension is associate with non-dipping pattern of BP and is more common MS. Based on our research we assume that sodium restriction can partially re-establish the normal circadian pattern of blood pressure. Reduction in sodium intake could be an especially important component in reducing blood pressure in patients with risk factors for metabolic syndrome.