Real-time measurement of glomerular filtration rate.

PURPOSE OF REVIEW: Measurement of glomerular filtration rate is an essential tool for determining the health or dysfunction of the kidney. The glomerular filtration rate is a dynamic function that can change almost instantaneously in response to stressors. Despite its central role in nephrology, there are no techniques available to the clinician for monitoring glomerular filtration rate in real time. Recent advances in technology to measure fluorescent compounds through the skin are providing a new approach for real-time monitoring of glomerular filtration rate. This review frames these technologies within how such measurements might be used in clinical medicine.

RECENT FINDINGS: Fluorescent molecules that act as ideal filtration markers are now available. Using transdermal sensors, the plasma disappearance rate of these exogenous markers can be measured rather than their steady state concentration. This eliminates the delay inherent in using an endogenous marker of filtration and permits continuous monitoring of GFR.

SUMMARY: These new technologies provide enhanced opportunities for diagnosis of kidney dysfunction and therapeutic monitoring. Accurate assessment of measured GFR will eliminate the erroneous diagnosis of chronic kidney disease (CKD) from many patients. Assessment of renal reserve will provide a new risk factor for progression of CKD. Real-time monitoring of GFR in critically ill patients will allow for earlier diagnosis of acute kidney injury and a dynamic metric to guide therapeutics. These are but a few of the many opportunities that this new technology will provide in both the clinical and research arenas.