Functional Reserve of the Kidney

An exploration of the normal limits of physiologic responses and how these responses are lost when the kidney is injured rarely occurs in clinical practice. However, the differences between ?resting? and ?stressed? responses identify an adaptive reactiveness that is diminished before baseline function is impaired. This functional reserve is important in the evaluation of prognosis and progression of kidney disease. Here, we discuss stress tests that examine protein-induced hyperfiltration, proximal tubular secretion, urea-selective concentration defects, and acid retention. We discuss diseases in which these tests have been used to diagnose subclinical injury. The study and follow-up of abnormal functional reserve may add considerable understanding to the natural history of CKD.

Automated summary

Exploring the normal limits of physiologic responses and their loss in kidney injury is important for evaluating prognosis and progression of kidney disease. Stress tests can detect changes in functional reserve and be used to diagnose subclinical injury. Studying and monitoring abnormal functional reserve can provide insights into the natural history of chronic kidney disease.