THE LINK BETWEEN HYPERTENSION AND NEPHROSCLEROSIS

Nephrosclerosis is literally defined as hardening of the kidneys (Gree k derivation: nephros, kidney; sklerosis, hardening). It is the result of scarring or replacement of the normal renal parenchyma by dense co llagenous tissue. In practice, nephrosclerosis refers to diseases with predominant pathologic changes occurring in the preglomerular microva sculature and secondarily involving the glomeruli and interstitium. Th e relationship between mild to moderate hypertension and either nephro sclerosis or end-stage renal disease (ESRD) remains circumstantial, al though these syndromes have long been associated in the medical litera ture. Nephrologists credit hypertension as the etiology of nephroscler osis in 25% of patients initiating Medicare-supported renal replacemen t therapy, even though other processes may cause similar renal patholo gic findings. Strikingly, serum creatinine values infrequently increas e in patients with long-standing mild to moderate hypertension. Patien ts classified as having hypertensive ESRD typically present with advan ced disease, making the processes that initiated the renal disease dif ficult to detect. Nephrologists are twice as likely to label an Africa n-American patient as having hypertensive nephrosclerosis, compared wi th a white patient, when presented with identical clinical histories. This review proposes that many patients classified as having hypertens ive nephrosclerosis actually have intrinsic renal parenchymat diseases , renal artery stenosis, unrecognized episodes of accelerated hyperten sion, or a primary renal microvascular disease. The familial clusterin g of ESRD attributed to hypertension in African-Americans and the iden tification of genes associated with renal injury in animals support th e concept that inherited factors may predispose to renal failure. Afri can-American families often have members with ESRD from disparate etio logies, including hypertensive ESRD. This suggests that common mechani sms, be they inherited or environmental, underlie the development of p rogressive renal failure in diverse forms of nephropathy. Identificati on of the mechanisms producing susceptibility to progressive renal dis ease would support the concept that mild to moderate elevations in blo od pressure per se are uncommon causes of nephrosclerosis. (C) 1995 by the National Kidney Foundation, Inc.