1. In all three renin sub-groups of essential hypertension, the state of sodium balance determines the degree of participation of the renin-angiotensin system in sustaining high blood pressure.
2. Even the low-renin type can become renin-dependent when sufficient sodium depletion has been achieved.
3. The main difference between patients of these sub-groups appears to be their variable capacity to become depleted of sodium under standard dietary regimens.