- High PENK levels do not predict kidney failure in dialysis patients.
- This marker works for healthy kidneys, not those on machines.
- Dialysis clears this protein, but it doesn't track your GFR.
When Your Kidneys Stop Working
Imagine your kidneys as a complex filtration plant. They clean your blood, remove waste, and balance fluids. When this plant fails completely, it is called end-stage kidney disease.
About 37 million people worldwide have chronic kidney disease. For many, the damage is so severe that their kidneys can no longer keep up. These patients need dialysis to survive.
Doctors currently use specific markers to track how well a patient's remaining kidney function is working. One of these markers is Proenkephalin A 119–159, often called PENK.
Why This Marker Failed Here
In people with healthy or partially working kidneys, high PENK levels usually mean the filtration rate is dropping. It acts like a warning light on a dashboard.
But here's the twist: this warning light does not work the same way when the engine is completely off.
A new study looked at 100 patients who were already on maintenance hemodialysis. These are people whose kidneys have stopped working well enough to need a machine.
Researchers measured PENK levels before and after a dialysis session. They also checked other common markers like creatinine and blood urea nitrogen.
The results were surprising for anyone hoping to use PENK in this setting. There was no link between PENK levels and the estimated glomerular filtration rate.
In plain English, the amount of PENK in the blood did not change based on how well the patient's kidneys were filtering. The numbers stayed flat regardless of the patient's condition.
This held true even for patients who still made some urine. In those cases, PENK levels still did not match their kidney function.
How Dialysis Changes The Picture
Think of dialysis as a powerful vacuum cleaner. It sucks waste out of your blood. During the session, the machine successfully removes PENK from the bloodstream.
However, removing the protein does not tell you how much waste is still sitting in your body. The study showed that while BUN (a waste product) dropped significantly, PENK levels did not provide useful data for doctors.
If you or a loved one is on dialysis, do not look for PENK tests to monitor your progress. These tests are designed for earlier stages of kidney disease.
Your medical team will continue to use standard tests like creatinine and eGFR. These tools remain the most reliable way to track your treatment.
The Limitations
This study only looked at patients on dialysis. It did not test people with early-stage kidney disease. That is where PENK is still very useful.
The researchers were clear: this marker is not a replacement for current methods in advanced kidney failure.
Doctors will keep using proven methods to manage dialysis patients. Research continues to find better ways to monitor health, but PENK is not one of them for this group.
Talk to your nephrologist about the best tests for your specific situation. They know your history and can guide you on what matters most.
