[Day-night differences of arterial pressure in "white coat" arterial hypertension].

Prevalence and day-night differences of blood pressure (BP) are studied in "White Coat" Hypertension (AHT). An outpatient register of BP was performed during 24 hours in 95 patients with mild AHT. "White Coat" Hypertension was defined when diastolic BP during the day was below 90 mmHg (WCH group) and with no "White Coat" Hypertension (non-WCH) when it was over said figure. BP values for WCH group (n = 36) in comparison with non-WCH (n = 59) were: Day period 130 +/- 13/85 +/- 4 versus 143 +/- 14/99 +/- 7 mmHg (p < 0.001; p < 0.001). Night period 119 +/- 18/74 +/- 8 versus 127 +/- 15/84 +/- 8 mmHg (p < 0.05/p < 0.001). Day-night differences in BP were lower in WCH in comparison with non-WCH group: 11 +/- 9/11 +/- 8 versus 17 +/- 10/15 +/- 7 mmHg (p < 0.01; p < 0.01). A positive correlation was observed between BP variability in 24 hours and day-night difference in non-WCH group (Systolic BP: r = 0.512, p < 0.001; Diastolic BP: r = 0.676, p < 0.001). This correlation was not found in the WCH group. "White Coat" Hypertension is present in 38% of the subjects with mild AHT and could constitute an independent aspect of the alert reaction.