DIAGNOSIS OF MILD HYPERTENSION BY AMBULATORY BLOOD-PRESSURE MONITORING

Background Between 20% and 30% of patients with clinically diagnosed h ypertension have normal blood pressure (BP) values during automated am bulatory 24-hour BP monitoring. It has not been clear, however, whethe r these patients can be regarded as normotensive or whether they shoul d be treated in the same way as confirmed hypertensive patients. Metho ds and Results Ambulatory BP monitoring was performed in 88 normal con trol subjects and 171 hypertensive patients (office diastolic BP great er than or equal to 90 mm Hg on three visits; never treated or off tre atment for more than 6 months). Hypertensive patients were classified as nonconfirmed or white coat (n=58) if their 24-hour diastolic averag es were <85 mm Hg and at least 15 mm Hg lower than their office values . For comparisons, white coat patients were pair-matched with normal s ubjects by 24-hour diastolic averages and sex, and by similar age and weight; there were 40 such pairs. White coat patients were likewise pa ir-matched with confirmed hypertensive patients by identical office BP s (51 pairs). Participants were studied by individualized treadmill te sting, Doppler echocardiography, and assays of resting plasma catechol amines, upright plasma renin and aldosterone, and lipid, glucose, and insulin concentrations. Because of the matching, compared with normal subjects, patients with white coat hypertension and normal subjects ha d identical 24-hour BP averages. The white coat patients exhibited sli ghtly greater variability among individual readings (obtained each 15 minutes) throughout the day [P<.05]), but there were no differences in hemodynamic responses to exercise. Plasma norepinephrine (P<.05), ren in and aldosterone (P<.01 for each), and insulin and low-density lipop rotein cholesterol levels (P<.01 for each) were higher in the white co at group, as were left ventricular septal wall (P<.05) and muscle mass (P=.07) echocardiographic measurements. When compared with the confir med hypertensive patients, the white coat patients had higher renin (P <.01) but were otherwise similar. Within the white coat group, plasma norepinephrine correlated with total cholesterol and triglycerides (P< .05 for each), and aldosterone correlated with left ventricular mass ( P<.01); there were no significant correlations within the normal contr ol subject or confirmed hypertension groups. Conclusions Patients with white coat hypertension differ in metabolic, neuroendocrine, and card iac findings from normal control subjects and have greater BP variabil ity. These changes appear to be mediated by heightened activity of the sympathetic and renin-angiotensin systems. Although these characteris tics could reflect an alerting reaction in the clinic due to awareness of their diagnosis, the white coat hypertensive patients also have ev idence for additional, more-sustained differences from normal subjects . Thus, this condition appears to be a true variant of hypertension.