The development of the clearance concept.
The clearance concept is central to three critical areas of nephrology; it was a key feature to early conceptual analysis of the nature of urine formation, it was utilized as a measure of kidney function in advancing renal diseases, and it was a pivotal concept to elucidate the physiology of the kidneys. This paper describes the clearance concept as currently understood and then it examines how clearance was utilized to understand these various aspects of kidney function.