DIETARY SODIUM RESTRICTION REDUCES NOCTURNAL BLOOD PRESSURE IN PATIENTS WITH TREATMENT RESISTANT HYPERTENSION

Abstract

Objective: Patients with treatment resistant hypertension (TRH) are characterised by lack of blood pressure (BP) control despite antihypertensive treatment. They are at particular risk of cardiovascular disease and more likely to experience BP increase as a response to sodium loading than other individuals. In this study, we aimed to analyse if self-performed dietary sodium restriction could be implemented in patients with TRH. Moreover, we aimed to analyse the effect of this on nocturnal and 24h BP, and how BP changes were correlated to changes in plasma levels of BNP, nitric oxide and body water content. Design and method: The study was conducted as an interventional cross-over study including patients with TRH from 20-70 years. Patients were screened with 24h ambulatory BP monitoring initiated after observed intake of usual antihypertensive medication. They were included if 24h systolic BP>130/80 mmHg. Study participation included two periods of 14 days; a standard period with usual diet and an interventional period with instructed dietary sodium restriction and handed-out sodium-free bread. At the end of each period, patients were examined with 24h BP monitoring, 24h urine collection (sodium excretion), blood samples (nitric oxide, BNP), and bioimpedance measurement (body water content). Results: Participation was completed by 15 patients with mean age 59 years and mean 24h BP 144/82 mmHg. Mean baseline urinary sodium excretion was 192(86) mmol/24h (11.2 grams of salt). As seen in Table 1, sodium excretion was reduced to 91 mmol/24h equalling 5.3 grams of salt. BP levels were reduced significantly. Plasma levels of nitric oxide increased significantly, and this was correlated to the change in 24h BP. Total body water content and plasma levels of BNP was reduced significantly. The changes in BP were not correlated to changes in sodium excretion, body water or BNP. Conclusions: Self-performed dietary sodium restriction could be implemented resulting in a significant reduction in BP levels. BP change was not related to changes in body water or sodium excretion. Increased levels of nitric oxide may be evidence of improved endothelial function and may be one of the involved mechanisms in BP decrease following sodium restriction