Does antihypertensive therapy protect the kidney in essential hypertension?

AIM

To review the beneficial effect on renal function of antihypertensive treatment in patients with essential hypertension.

EPIDEMIOLOGY

Several prospective, randomized trials have demonstrated that blood pressure control reduces the incidence of stroke and coronary heart disease mortality but end-stage renal disease secondary to essential hypertension has increased by 16-26% during the last decade. This apparent discordance can be explained by the reduction in brain and heart mortality, so that a greater proportion of renal damage is produced, or by a failure of antihypertensive drugs to protect the kidney as efficiently as other organs. MECHANISMS OF RENAL DAMAGE IN ESSENTIAL HYPERTENSION: Two mechanisms have been proposed. One hypothesis is that renal ischemia affects different kidney zones by producing periglomerular fibrosis, intimal amplification with hyaline deposits and reduction of the vessel lumen. The second hypothesis proposes that the elevation of intraglomerular pressure observed with secondary glomerular sclerosis is regulated by afferent-efferent arteriolar vasoconstriction or vasodilation. PARAMETERS FOR MEASURING RENAL FUNCTION: Creatinine clearance is the most appropriate method to measure glomerular filtration rate in routine clinical practice. Serum creatinine is not elevated until renal function is reduced below 50 ml/ min. The Cockcroft formula has been proposed in order to calculate creatinine clearance from plasma creatinine levels. Microalbuminuria and proteinuria are two other parameters that can be used to measure renal damage. ANTIHYPERTENSIVE TREATMENT: Antihypertensive therapy with concomitant control of blood pressure reduces protein excretion and the hypertension-induced deterioration in renal function. Angiotensin converting enzyme (ACE) inhibitors and calcium antagonists have shown good renal protection, and a combination of these two types of drugs may improve results and reduce side effects.

CONCLUSIONS

In the past decade, end-stage renal disease secondary to essential hypertension is increased despite a clear reduction in stroke and coronary heart disease mortality resulting from blood pressure control. Measurements of creatinine clearance, serum creatinine in advanced renal failure, microalbuminuria and proteinuria are adequate indicators of renal damage. Blood pressure control with any class of drugs reduces the progression of renal failure and proteinuria, but ACE inhibitors and calcium antagonists seem to provide better renal protection; ACE inhibitors have a greater antiproteinuric effect. The combination of these two types of drugs might further reduce renal damage and side effects.