Beyond Creatinine: First Real-World Evidence Highlights Proenkephalin A 119–159 (penKid) as a Valuable Kidney Function Biomarker
• Real-World Implementation:
Proenkephalin A 119–159 (penKid) has been successfully integrated into daily practice in intensive care unit (ICU), demonstrating its effectiveness in assessing kidney function and predicting acute kidney injury (AKI) in over 4,000 patients.
• Superior Dynamics:
PenKid augments traditional markers by detecting rapid changes in kidney function, particularly beneficial in critically ill patients where timely information is crucial.
• Clinical Impact:
PenKid proved valuable in identifying high-risk patients at ICU admission, especially those with a normal serum creatinine. Additionally, penKid provided valuable insights into kidney function during renal replacement therapy (RRT).
• International Recognition:
Beyond its use in reference hospitals in Germany, international experts, including those at the Mayo Clinic, acknowledge the added value of penKid on top of standard care.
Hennigsdorf/Berlin, Germany, April 16, 2025 -
Diagnostic company SphingoTec GmbH (“SphingoTec”) announces the publication of real-world data on the effectiveness of Proenkephalin A 119–159 (penKid) in improving kidney function assessment in intensive care units (ICUs) (1). This study confirms penKid's value in identifying high-risk patients at admission and supporting the management of renal replacement therapy (1). The published data complement a recent review from the Mayo Clinic that highlights penKid's potential as a new method to measure renal function beyond creatinine (2).
Acute kidney injury (AKI) is a significant challenge in intensive care units (ICUs), affecting up to half of all patients and leading to increased morbidity and mortality (1). Traditional markers like serum creatinine have limitations, as they may not detect kidney dysfunction until significant damage has occurred. A recent study from the University Hospital Aachen marks the first publication based on real-world data from over 4,000 patients, reporting the outcome implementation of penKid in daily practice.
Study Overview
During a two-year period, the University Hospital Aachen, Germany implemented penKid in their ICU (1). The study analyzed almost 18,000 penKid measurements from 4,169 patients, including the use of a penKid-GFR formula to estimate glomerular filtration rate (GFR). PenKid outperformed traditional markers in assessing kidney function and remained dynamic under RRT, supporting clinical decision-making in critical care.
Key Findings
The data show that penKid allows for a significantly better assessment of renal dysfunction upon admission, particularly in identifying patients at risk of developing severe AKI. In patients with normal serum creatinine levels at admission, penKid and its GFR formula outperformed traditional methods in predicting AKI within 24 and 48 hours.
As penKid is effectively removed by RRT, as demonstrated by studies such as Lorenzin et al. (3), persistently elevated levels during RRT may indicate ongoing renal dysfunction, while declining levels could signal renal recovery. This dynamic nature of penKid – even during ongoing RRT - can support decisions that may optimize RRT duration and reduce associated risks.
Clinical Significance
Prof. Dr. Gernot Marx, the Director of the Clinic for Operative Intensive Care and Intermediate Care at Uniklinik RWTH Aachen highlights, "After using penKid in clinical settings for five years, I see significant value in specific use cases due to its swift dynamics, addressing creatinine blind spots. The published data confirms our clinical observations and paves the way for bringing innovation into daily practice." Early detection of compromised renal function could allow for timely interventions, reducing the risk of emergency RRT and improving the chance for full renal recovery. In RRT scenarios, penKid could help de-escalate treatments and prevent unnecessary RRT, potentially reducing ICU stays.
Recent Review
The critical care community is seeking tools for improving kidney health assessment, as indicated by a recent review published by researchers from the Mayo Clinic (2). This review highlights penKid's ability in detecting rapid GFR changes and predicting AKI, particularly in critically ill patients. PenKid's strong correlation with measured GFR makes it a valuable tool, enabling more accurate and timely assessments of kidney function. The Mayo Clinic review also notes that penKid's ability to predict major adverse kidney events, such as worsening renal function and the need for RRT, aligns with its potential to provide valuable prognostic information in clinical settings.
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References
1. Martin, L. et al. Implementation and One-Year Evaluation of Proenkephalin A in Critical Care. Int. J. Mol. Sci. 2025, 26, 2602. https://doi.org/10.3390/ijms26062602
2. Sheikh MS, Kashani KB. Beyond creatinine: New methods to measure renal function? Eur J Intern Med. 2025 Jan 31:S0953-6205(25)00025-1. doi: 10.1016/j.ejim.2025.01.015.
3. Lorenzin, A. et al. Human Proenkephalin A 119-159 (penKid) in Extracorporeal Therapies: Ex vivo Sieving Coefficient, Diffusive Clearance, and Hemoadsorption Kinetics. Blood Purif. 2024, 53, 773–780. doi: 10.1159/000540061.
About SphingoTec
SphingoTec GmbH ("SphingoTec"; Hennigsdorf near Berlin, Germany) is a diagnostic company focusing on the out-licensing of innovative critical care biomarkers for diagnosing, predicting, and monitoring acute medical conditions. SphingoTec develops its biomarkers to the commercial stage and partners with IVD companies to make them available on different IVD platforms. SphingoTec's proprietary biomarker portfolio includes Proenkephalin A 119-159 (penKid), a biomarker for the assessment of kidney function in critical diseases, commercially available on diagnostic platforms AFIAS and Nexus IB10 and bioactive Adrenomedullin 1-52 (bio-ADM), a biomarker for the assessment of endothelial function in conditions like sepsis. Discover more on www.sphingotec.com
Contact:
Ruxandra Lenz
Head of Marketing and Communication
SphingoTec GmbH
Phone +49-3302-20565-0
Email: press@sphingotec.com
• New ELISA sphingotest® penKid® enables widespread measurement of the kidney function biomarker Proenkephalin 119-159 (penKid) using standard laboratory equipment. • Only available test to match SphingoTec’s reference chemiluminescence assay, developed with patented high-sensitivity technology to provide consistent results across platforms. Hennigsdorf/Berlin, Germany, April 28 2026 - SphingoTec GmbH announces the launch of the ELISA sphingotest® penKid®, a new assay designed to make testing of its proprietary biomarker broadly accessible to research laboratories and pharmaceutical partners. Providing ease-of-use and precision, the test facilitates large-scale investigations of human kidney function in both acute and broader clinical research contexts. Responding to growing research interest The launch follows increasing demand from the scientific community to study penKid - a biomarker reflecting the current state of kidney function in critical care environments. While SphingoTec’s high-sensitivity sphingotest® penKid® assay serves as the reference method for clinical research and third-party IVD assays, the assay technology requiring dedicated equipment was not easily adoptable in research laboratories. The new ELISA sphingotest® penKid® now allows researchers worldwide to benefit from SphingoTec’s patented detection technology using standard photometers, extending penKid testing capability to a wider range of laboratories. Proven performance and data continuity The ELISA sphingotest® penKid® has been developed to achieve excellent correlation with SphingoTec’s reference chemiluminescence assay, ensuring consistent, high-quality results across different assay platforms. Both methods share the same underlying technology capable of detecting penKid concentrations in the picomolar range. Thanks to this technology transfer, researchers can rely on the same analytical precision and reliability that supported the clinical studies establishing penKid as a valuable kidney function biomarker. The assay’s robust design and German manufacturing ensure durable consistency and reproducibility. With this research-use ELISA, SphingoTec responds to the increasing availability of non-validated assays and encourages researchers to not compromise assay quality and performance to ensure trustworthy results - since data from non-validated tests may reflect assay limitations rather than the true performance of the penKid biomarker. Complementary approaches for clinical use and scientific exploration SphingoTec pursues its commercial strategy for the biomarker penKid through strategic out-licensing partnerships such as Boditech Med, which has developed an IVDR-certified assay for routine clinical use and rapid diagnostics. The newly launched ELISA sphingotest® penKid® represents a complementary initiative, specifically designed to support high-throughput clinical and translational research. Through this dual approach, SphingoTec reaffirms its commitment to fostering scientific collaboration and promoting the broader exploration of penKid across diverse research settings. “Developing the ELISA sphingotest® penKid® reflects our long-term commitment to improving critical care diagnostics,” said Deborah Bergmann, Managing Director and CEO of SphingoTec GmbH. “Beyond its currently validated clinical applications, we see strong potential for penKid to support research and improve diagnostics in other fields where kidney function is relevant. By encouraging scientists worldwide to incorporate penKid into their studies and clinical programs, we aim to accelerate innovation and advance best-fit diagnostic solutions that ultimately improve patient care.” About SphingoTec SphingoTec GmbH ("SphingoTec"; Hennigsdorf near Berlin, Germany) is a biomarker company focusing on the out-licensing of innovative critical care solutions for diagnosing, predicting, and monitoring acute medical conditions. SphingoTec develops its biomarkers to the commercial stage and partners with IVD companies to make them available on different IVD platforms. SphingoTec's proprietary biomarker portfolio includes Proenkephalin A 119-159 (penKid), a biomarker for the assessment of kidney function in critical diseases, and bioactive Adrenomedullin 1-52 (bio-ADM), a biomarker for the assessment of endothelial function in conditions like sepsis. Discover more on www.sphingotec.com Media Contact: Email: press@sphingotec.com Phone +49-3302-20565-0 SphingoTec GmbH Neuendorfstr. 15A 16761 Hennigsdorf, Germany
• PenKid surpasses serum creatinine on Day 1 post-transplant in detecting delayed graft function (DGF), with an AUROC of 0.87 versus 0.56 for creatinine. • PenKid differentiates slow graft function (SGF) from DGF up to 8 days earlier than current methods, supporting more timely clinical decisions. • PenKid levels remain unaffected by kidney replacement therapy (KRT), allowing for more accurate assessment of kidney function. • Independent validation in transplant cohort from Australia confirms performance and broad applicability. Hennigsdorf/Berlin, Germany, July 1, 2025 - Diagnostic company SphingoTec GmbH (“SphingoTec”) announces a landmark study (1) published in Transplant International, led by Heidelberg University Hospital in Germany in collaboration with researchers from Sydney, Australia, which identifies Proenkephalin A 119-159 (penKid) as a reliable biomarker for early and precise assessment of graft function trajectories following kidney transplantation. The research demonstrates that PenKid not only identifies patients at risk for DGF significantly earlier than traditional markers but also distinguishes between slow and delayed graft function with remarkable accuracy, offering clinicians a valuable new tool for patient management. The study prospectively evaluated 159 consecutive kidney transplant recipients at Heidelberg University Hospital and validated findings in an independent cohort from Sydney. PenKid consistently outperformed serum creatinine (SCr) in predicting graft function trajectories, particularly in the critical early post-transplant period. Notably, PenKid’s ability to remain unaffected by KRT—a treatment for severe kidney dysfunction—further sets it apart from SCr, which can be influenced by non-renal factors and KRT itself, thereby enhancing the reliability of graft function assessment. Multivariate analysis confirmed PenKid as the strongest independent predictor of both short-term graft function and 30-day outcomes, underscoring its clinical utility for early risk stratification. The biomarker’s superior granularity allows for nuanced classification of DGF severity, supporting more informed decisions regarding the initiation of dialysis or biopsy and offering potential for individualized patient care. With these findings, penKid steps forward as a practical addition to the transplant clinician’s toolkit, promising to sharpen decision-making for optimal outcomes. Its adoption could help transplant teams act with greater confidence and precision, ultimately strengthening the standard of care in kidney transplantation. ## References 1. Benning L et al. (2025) Proenkephalin A 119-159 in Kidney Transplantation: A Novel Biomarker for Superior Tracking of Graft Function Trajectories. Transpl. Int. 38:14366. doi: 10.3389/ti.2025.14366 About SphingoTec SphingoTec GmbH ("SphingoTec"; Hennigsdorf near Berlin, Germany) is a biomarker company focusing on the out-licensing of innovative critical care solutions for diagnosing, predicting, and monitoring acute medical conditions. SphingoTec develops its biomarkers to the commercial stage and partners with IVD companies to make them available on different IVD platforms. SphingoTec's proprietary biomarker portfolio includes Proenkephalin A 119-159 (penKid), a biomarker for the assessment of kidney function in critical diseases, commercially available on diagnostic platforms AFIAS and Nexus IB10 and bioactive Adrenomedullin 1-52 (bio-ADM), a biomarker for the assessment of endothelial function in conditions like sepsis. Discover more on www.sphingotec.com Contact : Ruxandra Lenz Marketing and Communication SphingoTec GmbH Phone +49-3302-20565-0 Email: press@sphingotec.com