Factors participating in blood pressure elevation after discharge from the hospital in patients with essential hypertension.
We followed the changes in blood pressure (BP) after discharge from the hospital in 32 patients with essential hypertension whose BP was normalized on a diet containing 7g/day of NaCl during hospitalization. They were divided into two groups on the basis of BP changes: 18 patients whose BP values were elevated by more than 10% after discharge (group I; mean +16.9%, P less than .01) and the remaining 14 patients (group II; -3.6%, P = NS). Urinary Na excretion (UNaV) in Group I patients increased markedly after discharge (83 v 189 mu Eq/min, P less than .001) while it did not change in Group II (122 v 102 mu Eq/min, P = NS), resulting in a greater postdischarge UNaV in group I than in group II (P less than .01). The changes in BP were positively correlated with the overall changes in UNaV (r = 0.45, P less than .01). Plasma epinephrine after discharge was higher in group I than in group II (31 v 18 pg/mL, P less than .05). Thus, increases in NaCl intake seem to play an important role in BP elevation after discharge. Adrenal medullary function may partly contribute also to the BP elevation.