1. Studies were prospectively performed on 72 hospitalized patients with essential hypertension. Blood pressure was normalized within 1 week of admission in 33 patients (group I), but did not decrease in 39 patients (group II). To determine the factors that differentiate group I from group II, cardio-renal haemodynamic and endocrinological indices were evaluated using multivariate analysis.
2. Systolic, diastolic and mean blood pressures on admission were higher in group II (P < 0.001), whose optic fundi showed more severe changes (P < 0.001). Although group II had greater left ventricular posterior wall thickness (P < 0.02), left ventricular mass index (P < 0.05) and systemic vascular resistance (P < 0.01) on echocardiography, their cardiac index and ejection fraction were comparable with those of group I.
3. Renal blood flow (P < 0.05) and glomerular filtration rate (P < 0.01) were lower in group II than in group I. Renal vascular resistance was more elevated (P < 0.01) in group II than in group I.
4. After severe sodium depletion and ambulation, group I showed a greater increase in plasma noradrenaline and adrenaline (P < 0.05). On multivariate analysis, those with lower systolic blood pressure, better renal function and more reactive sympathetic nervous system were discriminated as group I.
5. These data suggest that group I patients have lower systolic blood pressure on admission, greater sympathetic reactivity and better renal function, all of which contribute to their spontaneous blood pressure fall after admission.