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Clin J Am Soc Nephrol. 2012 Feb;7(2):315-22. doi: 10.2215/CJN.02060311. Epub 2011 Nov 23.

Association of urinary sodium/potassium ratio with blood pressure: sex and racial differences.

Author information

1
Renal Section, Medical Service, Veterans Affairs North Texas Health Care System, Dallas, TX 75216-7167, USA. susan.hedayati@utsouthwestern.edu

Abstract

BACKGROUND AND OBJECTIVES:

Previous studies reporting an association between high BP and high sodium and low potassium intake or urinary sodium/potassium ratio (U[Na(+)]/[K(+)]) primarily included white men and did not control for cardiovascular risk factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:

This cross-sectional study investigated the association of U[Na(+)]/[K(+)] with BP in 3303 participants using robust linear regression.

RESULTS:

Mean age was 43±10 years, 56% of participants were women, and 52% were African American. BP was higher in African Americans than in non-African Americans, 131/81±20/11 versus 120/76±16/9 mmHg (P<0.001). Mean U[Na(+)]/[K(+)] was 4.4±3.0 in African Americans and 4.1±2.5 in non-African Americans (P=0.002), with medians (interquartile ranges) of 3.7 (3.2) and 3.6 (2.8). Systolic BP increased by 1.6 mmHg (95% confidence interval, 1.0, 2.2) and diastolic BP by 1.0 mmHg (95% confidence interval, 0.6, 1.4) for each 3-unit increase in U[Na(+)]/[K(+)] (P<0.001 for both). This association remained significant after adjusting for diabetes mellitus, smoking, body mass index, total cholesterol, GFR, and urine albumin/creatinine ratio. There was no interaction between African-American race and U[Na(+)]/[K(+)], but for any given value of U[Na(+)]/[K(+)], both systolic BP and diastolic BP were higher in African Americans than in non-African Americans. The diastolic BP increase was higher in men than in women per 3-unit increase in U[Na(+)]/[K(+)] (1.6 versus 0.9 mmHg, interaction P=0.03).

CONCLUSIONS:

Dietary Na(+) excess and K(+) deficiency may play an important role in the pathogenesis of hypertension independent of cardiovascular risk factors. This association may be more pronounced in men than in women.

PMID:
22114147
PMCID:
PMC3280031
DOI:
10.2215/CJN.02060311
[Indexed for MEDLINE]
Free PMC Article

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