Plasma Renin Activity and Hypertensive Organ Manifestations in 50‐year‐old Males

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Abstract
From a screening examination in a randomly selected third of the 50 yr old male population in Goteborg, Sweden, 10% subsample was selected as a reference group (n = 80). All untreated persons with SBP [Systolic blood pressure] > 175 or DBP [diastolic blood pressure] > 115 mmHg on 2 separate occasions made up the hypertension group (n = 35). The reference group and the hypertension group were subjected to the same investigations, including BP measurement before and after rest and determination of plasma renin activity (PRA), urinary Na and norepinephrine excretion and GFR [glomerular filtration rate]. Plasma renin activity was approximately normally distributed in both the reference and the hypertension group. Mean values were 0.78 .+-. 0.18 and 0.65 .+-. 0.17 ng/ml per h, respectively, the difference being almost statistically significant (0.10 > p > 0.05). There was no difference with respect to Na excretion between the reference group and the hypertension group. In the reference group, heart rate was positively correlated to PRA and to urinary norepinephrine excretion during the day. No linear correlation between PRA and BP was found, either in the reference group, or in the hypertension group. Na excretion during the day was positively correlated to GFR in the hypertension group, but not in the reference group. Compared to hypertensives with normal or high Na excretion during the day, the hypertensives with low Na excretion during the day were characterized by a higher BP, a lower GFR and a reversed diurnal rhythm of urine excretion. Thus, low Na excretion seemed to indicate more severe hypertension with increased renal resistance during the day. The hypertension group was also divided with regard to Na excretion into a low, normal and high renin group. The low renin group had the lowest GFR and with rising renin group (from low via normal to high) there was a significant increase in GFR and a significant decrease in resting BP. Low renin hypertension is not a more mild, but indeed rather a more severe form of hypertension.