A peer-reviewed study published in Physiological Reports is the first evaluation of Proenkephalin A 119-159, or penKid, as a marker of kidney functional reserve, a stress test designed to reveal loss of kidney capacity that may not be apparent from routine blood tests. SphingoTec said the results extend the published evidence for the biomarker beyond acute kidney injury into a potential complementary application.
Researchers at the University of New South Wales and Prince of Wales Hospital in Sydney studied 62 participants: 40 patients having heart surgery and 22 healthy people, among them volunteers, kidney donors and patients who had received a kidney auto-transplant. Participants drank a protein shake and gave hourly blood samples over five hours, and urine samples were collected for creatinine clearance testing.
Filtration rises for a few hours after high protein intake, and the study measured that extra work. penKid showed the largest dynamic response, with a median fractional change of 44.2 percent against 10.5 percent for cystatin C, while creatinine clearance rose by a median 30 percent. penKid reached its maximal response in about two hours, similar in timing to a two-hour diabetes test, and it differentiated healthy participants from cardiac surgery patients, who had a lower reserve; creatinine clearance did not. penKid measurements were also reported as more homogeneous than creatinine clearance measurements.
Prof. Zoltan H. Endre, the study's corresponding author and a researcher in the Department of Nephrology at Prince of Wales Hospital and the School of Clinical Medicine at the University of New South Wales, said penKid gave a fast, consistent read on how much filtration capacity a kidney still has in reserve, and that a signal captured that quickly turns a kidney stress test from a research tool into something a clinic could use.
The authors point to practical features of reserve testing with penKid: no urine collection is needed, only minimal fasting is required, and the assessment can be made from blood samples in near real time. SphingoTec, based in Hennigsdorf near Berlin, says penKid levels are not influenced by inflammation, age or sex, and that earlier studies showed it can detect acute kidney injury up to 48 hours before conventional criteria are met. More information is published at sphingotec.com.
