Renal function may deteriorate because of uncontrolled hypertension. Even minimal elevations in blood pressure (BP), still below the 140/90 mmHg level used to define hypertension, are associated with increased renal arteriosclerosis in autopsies . Since adequate control of hypertension slows the rate of renal dysfunction , the effects of antihypertensive therapy on renal function need to be carefully considered.
Antihypertensive therapy has both acute and chronic effects on renal function in patients with primary hypertension (formerly called "essential" hypertension). In early disease, for example, renal function is usually normal; in this setting, lowering the BP induces little change in glomerular filtration rate (GFR) . In comparison, some patients have early renal vasoconstriction leading to a fall in GFR below 80 mL/min. Reversal of the vasoconstriction with an angiotensin-converting enzyme (ACE) inhibitor or calcium channel blocker can raise the GFR by 20 to 30 mL/min in these patients . (See "Renal effects of ACE inhibitors in hypertension".) Blacks may have an initial decrease in GFR compared with an increase in whites .
Patients with prolonged uncontrolled hypertension are at increased risk of developing chronic renal failure . The risk of this complication is much greater in blacks and in patients with moderate and severe hypertension (figure 1). (See "Hypertensive complications in blacks".)
It must be emphasized, however, that the percentage of patients with mild hypertension who develop end-stage renal disease (ESRD) is relatively small, being less than 1 percent after 16 years in the MRFIT trial . (See "Clinical features, diagnosis, and treatment of hypertensive nephrosclerosis", section on 'Incidence of renal failure'.)
Prolonged blood pressure (BP) control will usually minimize the degree of renal damage, leading to a stable plasma creatinine concentration . There are, however, patients in whom proteinuria develops or the plasma creatinine concentration continues to rise slowly over a period of years despite seemingly adequate antihypertensive therapy. This is most likely to occur in blacks, in patients who have underlying chronic kidney disease (CKD) or a family history of ESRD, and in patients with vascular disease as manifested by older age, higher baseline BP, and hyperuricemia.