Dipping in Ambulatory Blood Pressure Monitoring Correlates With Overnight Urinary Excretion of Catecholamines and Sodium

Nondipping blood pressure ( BP ) is associated with increased morbidity and mortality. This study examines the relationship of “dipping” in 24‐hour ambulatory BP monitoring ( ABPM ) with awake and sleeping urinary norepinephrine ( NE ) and epinephrine ( EPI ), and that of urinary NE and EPI with urinary sodium ( UN a). Fifty nondippers and 65 dippers were included in the present study. Collected data included age, sex, body mass index, history of hypertension, current antihypertensive treatment, ABPM data, and NE , EPI, and UN a values. Hierarchical multiple regression analysis with the night‐to‐day ratio ( NDR ) of systolic BP as a dependent variable showed that the composite term of the NDR s of urinary NE and EPI was a significant predictor for dipping. Results also show a differential role of NE and EPI in circadian UN a excretion in dippers and nondippers. These results indicate that the sympathetic nervous system is involved in the regulation of circadian BP variations and UN a excretion.