Hypertension in chronic renal failure: An abnormal relation between sodium and the renin-angiotensin system

Hypertensive patients with chronic renal failure show evidence of an abnormal relationship between sodium and the reninangiotensin system in that circulating levels of renin and angiotensin II are abnormally high in relation to exchangeable sodium. The abnormality may well contribute to the hypertension in this syndrome. In a minority of cases blood pressure cannot be controlled by dialysis. In these, renin levels are particularly high and rise even further in response to therapeutic sodium depletion. It is suggested that this may perpetuate the hypertension. In most patients, however, blood pressure can be controlled by dialysis and, in these, renin and angiotensin II levels are lower, but, again, their relation to exchangeable sodium is abnormal. It is suggested that the rise in arterial pressure in this group results from a failure of renin to suppress normally with sodium retention. This would also explain the fall in blood pressure with sodium depletion at hemodialysis. The inflexibility of the renin-angiotensin system in its relation to sodium may be the cause of hypertension as well as the basis for its cure.