Hypertension and the kidney are closely linked in several ways. The kidney normally responds rapidly to changes in blood pressure by alteration of renal haemodynamics and
sodium excretion. These functions of the kidney are reset in established
hypertension. However, several subtle abnormalities of renal function are demonstrable in normotensive offspring of hypertensive parents, suggesting that the kidney may play a central role in the pathogenesis of
essential hypertension--a possibility supported by a number of cross-
transplantation studies in different animal models of
hypertension.
Hypertension itself commonly causes severe
renal failure when the malignant phase develops, but the question of whether benign
hypertension causes renal impairment remains controversial. Firm data that this is so are in general lacking, although in black subjects
hypertensive nephropathy appears to be up to 18-fold more frequent than in whites, and is reported as a common cause of
end-stage renal failure. The reasons for this racial difference in susceptibility to hypertensive renal injury remain unknown. Secondary
hypertension also commonly develops in patients with underlying renal disease, and the co-existence of
hypertension with renal impairment greatly worsens the rate of the deterioration of renal function. Effective treatment of
hypertension in renal disease, particularly with converting
enzyme inhibitors, is capable of slowing the rate of loss of function, both in animal models and in human disease, though in the latter case this benefit has so far been demonstrated unequivocally only in patients with
diabetic nephropathy.