Active ambulatory blood pressures and urinary electrolytes in young male subjects with normal blood pressure or borderline hypertension.

OBJECTIVES

To examine the relationship between ambulatory blood pressure (ABP) and 24-h urinary electrolytes in young subjects with normal blood pressure or borderline hypertension.

DESIGN

ABP shows a circadian profile. We question whether high- and low-level pressure spans might have a relationship with urinary salt output.

METHODS

ABP was monitored by the SpaceLabs 5200 system in 182 young male subjects (aged 17-25 years) with normal or borderline office blood pressure. In all subjects, 24-h urinary sodium, potassium and chloride were measured. The mean values and SD of ABP during 24 h, or during the daytime (0900-2100 h) and night-time (2115-0845 h), were estimated. In addition, using a 'cumulative sum' method, 'active' (high-level) and 'passive' (low-level) spans of APB were identified in each subject.

RESULTS

No relationship was found between 24-h urinary sodium, potassium or chloride and office systolic blood pressure. Also, no relationship was found between the electrolytes and mean value or SD of ABP during 24 h, daytime or night-time. In contrast, significant positive correlations were found between 24-h urinary sodium and active systolic and diastolic blood pressure. The present study suggests that the active blood pressure span is associated with salt intake in normal and borderline blood pressure groups.