White coat hypertension in adolescents: Increased values of urinary cortisol and endothelin

Objective: To investigate whether "white coat hypertension" (WCH) in adolescents is an innocent phenomenon or is associated with early changes of the vascular system and/or increased stress response, reflected in the urinary endothelin and cortisol values, respectively. Study design: The study group included 36 subjects, 14 with WCH (8 males and 6 females) aged 12.9 +/- 3 years and 22 normotensive control subjects (12 males and 10 females) aged 13 +/- 3.5 years. WCH was defined as systolic and/or diastolic blood pressure (BP) greater than or equal to 95th percentile for age, sex, and height and with reported normal BP measurements at home. Urinary endothelin (UET1), urinary free cortisol (UFC), and plasma renin levels were determined by radioimmunoassay; and urinary albumin levels were determined by nephelometry. For statistical analysis, the Mann Whitney U test, Spearman correlation coefficient, and multivariate analysis of variance/multivariate analysis of covariance were used, as applicable. Results: The 24-hour values of UET1 and UFC were greater in male subjects with WCH than in male control subjects (P = .02), whereas no such difference was found in female subjects. The difference in UFC values in male subjects was accounted for by the day values. In subjects with WCH, and not in control subjects, a positive correlation of UET1 to UFC (r = 0.59, P = .027), diastolic BP (r = 0.55, P = .04), and mean BP (r = 0.65, P = .012) was detected. Conclusions: Our data indicate that WCH in adolescence may not be an innocent phenomenon and may represent a prelude to permanent idiopathic hypertension of adulthood.