At risk nephrons and the decline in renal function in response to treatment of hypertension.

An examination of change in renal function following blood pressure lowering in more than 4,400 individuals in several clinical trials revealed that renal function declined following initiation of antihypertensive treatment in both essential hypertension and hypertensive diabetics for a period of two years before stabilizing at or near zero change. This initial decline can be related to the severity of preexisting hypertension but does not appear related to the type of antihypertensive regimen used. This phenomenon appears most readily explained by progressive obsolescence of previously damaged nephrons and not by the type of antihypertensive therapy employed. These finding raise questions about validity of interpretation of clinical trials designed to test efficacy of specific drug regimens in preserving renal function when outcome results are predominantly influenced by events during the first two years of intervention.