Proenkephalin (PENK) as a Novel Biomarker for Kidney Function

What is it about?

The assessment of kidney function and detection of acute kidney injury (AKI) remain cumbersome. In recent years, several biomarkers have been put forward (e.g., NGAL, KIM-1, TIMP-2*IGFBP-7), but clinical implementation is limited up to now. Proenkephalin (PENK) represents a new candidate to determine kidney function. This peptide is filtrated in the glomerulus and PENK plasma concentration appears to accurately represent glomerular filtration rate in patients diagnosed with sepsis or cardiac diseases. In this review, we present an overview of enkephalins and the assessment of kidney function using this possible new functional biomarker PENK and compare it with established and novel biomarkers.

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Why is it important?

This review presents an overview of the assessment of kidney function and prediction of development of acute kidney injury with the new functional biomarker proenkephalin (PENK). PENK is a stable surrogate marker for enkephalins of which its receptors are mainly expressed in the kidney. PENK was demonstrated to be a more accurate and timely biomarker for kidney function compared with serum creatinine in various patient groups, including patients with heart failure or sepsis. In addition, increased PENK concentrations have been shown to predict deterioration of kidney function and subsequent clinical outcomes. These results warrant confirmation in larger cohorts of patients.