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Salt intake, salt restriction, and primary (essential) hypertension

Author
Norman M Kaplan, MD
Section Editor
George L Bakris, MD
Deputy Editor
John P Forman, MD, MSc

INTRODUCTION

The relationship between sodium intake and blood pressure (BP), as well as the effects of sodium restriction in patients with uncomplicated primary hypertension (formerly called "essential" hypertension), are discussed in this topic review. The restriction of sodium intake and fluid removal with diuretics play an even more central role in the therapy of hypertension in those with hypertension associated with acute or chronic kidney disease. (See "Overview of hypertension in acute and chronic kidney disease", section on 'Benefits of sodium restriction'.)

The relationship of other factors to the development of hypertension, the evaluation of the hypertensive patient, and the management of hypertension in general and in specific subpopulations are discussed elsewhere. (See appropriate topic reviews.)

SODIUM INTAKE AND HYPERTENSION

Primary hypertension (formerly called "essential" hypertension) is seen primarily in societies with average sodium intakes above 100 meq/day (2.3 g sodium); however, it is rare in societies with average sodium intakes of less than 50 meq/day (1.2 g sodium) [1,2]. These observations suggest that the development of hypertension requires a threshold level of sodium intake. This effect appears to be independent of other risk factors for hypertension, such as obesity.

In addition to sodium, chloride (the accompanying anion in salt) also appears to be important in the pathogenesis of primary hypertension [3]. Increasing sodium chloride intake in sodium-sensitive patients leads to volume expansion and a rise in blood pressure (BP); neither of these findings is seen if sodium is given with another anion (such as citrate [which is metabolized to bicarbonate]) or chloride with another cation (such as ammonium) [3].

Reducing salt intake from 170 to 100 meq/day lowers the mean BP in normotensive adults by approximately 2/1 mmHg and in hypertensive adults by 5/3 mmHg (equal to that seen with most antihypertensive drugs) [4]. However, over the course of 30 years, the fall in BP may be greater, in part because salt restriction minimizes the normal rise in BP associated with aging [2].

                 

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Literature review current through: Nov 2016. | This topic last updated: Mon Jun 06 00:00:00 GMT 2016.
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