Fluorescent Detection Technology Advances Nephrology Care

A new noninvasive optical device measures glomerular filtration rate (GFR) in patients with normal or impaired renal function.

The MediBeacon (St. Louis, MO, USA) Transdermal GFR Measurement System (TGFR) is designed to provide clinicians continuous real-time measurements of GFR at the point of care, with no need for blood sampling or urine collection. The renal function system is comprised of MB-102, a fluorescent tracer agent, light emitting diodes (LEDs) that provide excitation of MB-102, a photodiode optical skin sensor that collects the emission light, and a system monitor. The fluorescent tracer agent is administered intravenously as a bolus, and subsequent light excitation is performed using the 450 nm amplitude-modulated LEDs.

The returning fluorescent light emission is measured at the sternum; after amplification and digitization, the data sets are stored in the internal memory of the device, which is later transferred to a PC via a USB connection; a basic PC software package is provided with the device. According to MediBeacon, GFR can be measured for a range of kidney functions, from normal to stage 4 chronic kidney disease (CKD). The system, which is currently in human trials, has not been approved for human use by any regulatory agency.

“Our goal is to establish the new gold standard for evaluating kidney function globally. This system is expected to be of tremendous value to patients with kidney disease,” said Steve Hanley, CEO of MediBeacon. “We also aspire to bring non-invasive monitoring, using light and our proprietary biocompatible fluorescent tracer agents and compounds, to other human health applications.”

Current clinical practice for renal function monitoring is to calculate estimated GFR (eGFR) using one of several empirically derived equations based on serum creatinine concentration (requiring a blood draw) and several other parameters, including height, weight, gender, and ethnicity. The resulting eGFR suffers from several drawbacks, including unreliable feedback during acute renal failure, an up to 72 hour delay before manifestation following renal insult or injury, and an up to 50% reduction in GFR before changes in serum creatinine concentration become evident.

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