Dynamic and Continuous Monitoring of Renal and Hepatic Functions with Exogenous Markers

Abstract

The liver and kidneys perform vital functions in the body and their numerous roles expose them to various forms of toxic materials and events. To prevent these organ failures, much effort has been devoted to the development of simple and reliable methods to monitor the functional status of the liver and the kidneys. All organ function measurements that use functional or clearance methods rely on the pharmacokinetics of endogenous biomarkers and various forms of exogenous radiopaque, radioactive, paramagnetic, photoactive, and organic molecules to monitor organ status. This review describes advances in the use of exogenous organ function-specific tracers for dynamic and continuous monitoring of renal and hepatic functions. Special emphasis is given to dynamic and continuous methods, which are illustrat- ed with selected organ-specific markers. Thus, we reviewed the use of microsomal and cytoso- lic enzyme activities on lidocaine, caffeine, antipyrine, aminopyrine, coumarin, galactose and amino acids for dynamic measurement of hepatic function. The continuous measurement approach was illustrated by the clearance of indocyanine green. Similarly, the use of creati- nine, iodinated aromatics, metal complexes, and organic dyes in dynamic and continuous renal function measurements is described. We conclude that the newer noninvasive continu- ous organ function monitoring with optical tracers, especially fluorescent markers, represents an important advance in patient care management.