New Formula Leverages Proenkephalin A 119-159 (penKid) for Improved GFR Estimation in Steady-State and Critically Ill Patients
• PenKid is a kidney function biomarker that correlates with gold standard GFR measurements in stable and acute kidney injury (AKI) patients.
• Based on penKid, a new formula was developed to estimate the GFR, outperforming widely used conventional equations based on creatinine alone.
• Scientists from Radboud University and Mayo Clinic developed and validated this formula in a large cohort of stable, as well as critically ill patients, laying the foundation for future increased clinical vigilance in kidney health assessment.
Hennigsdorf/Berlin, Germany, October 5, 2023 -
Diagnostic company SphingoTec GmbH (“SphingoTec”) announces that a new, improved formula has been developed for estimating the GFR using its kidney function biomarker penKid (1). According to the data, penKid strongly correlates with the measured GFR (mGFR), while the penKid-based formula for estimating GFR performs better than routinely used equations.
In clinical practice, kidney dysfunction is monitored using creatinine-based estimates of GFR. Creatinine is recognized as a late and insensitive biomarker of GFR, with consensus guidelines emphasizing that a more timely and accurate estimation of GFR in AKI is a relevant unmet medical need (2,3,4).
Researchers from the Radboud University Medical Centre, Netherlands, and Mayo Clinic, USA, have included a cohort of over 1,300 patients in a data-driven approach for developing an equation to estimate the GFR using the kidney function biomarker penKid (1). According to the findings, this novel equation performs better in calculating eGFR compared to creatinine-based equations. The formula can be applied to a wide range of patients since the cohort used for its development and validation included a broad spectrum of patients, such as patients with established chronic kidney disease, and critically ill patients. The compelling data is further strengthened by the fact that gold-standard methods to determine the true mGFR were used in all patients, and penKid concentration was most strongly correlated with mGFR.
Prof. Peter Pickkers (Head of Research in Intensive Care Medicine at Radboud University Nijmegen Medical Centre) summarized, “The innovative biomarker penKid has previously demonstrated significant potential in increasing the clinical vigilance and supporting the management of AKI patients. The penKid-based formula will facilitate in future its implementation in the clinical routine since it translates penKid concentrations into a more accurate GFR estimation that can now be implemented by physicians worldwide.“
Dr. Florian Uhle, Medical Director at SphingoTec, added, “With this landmark research, the first formula using penKid has been successfully established in chronic and acute kidney impairment. Starting from this evidence base, we will focus on further validating this formula in critically ill patients and aiming to overcome the shortcomings of our current diagnostic standards in AKI management. We are looking forward to interacting closely with global healthcare providers in the future to drive this concept to clinical reality.”
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References:
(1) Beunders et. al. Assessing GFR With Proenkephalin, Kidney International Reports, 2023, DOI: https://doi.org/10.1016/j.ekir.2023.08.006
(2) Chawla et al. Acute kidney disease and renal recovery: consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup. Nature Reviews Nephrology 2017; 13: 241-257.
(3) Ostermann et al. Report of the first AKI Round Table meeting: an initiative of the ESICM AKI Section. Intensive Care Med Exp 2019; 7: 69.
(4) Pickkers et al. The intensive care medicine agenda on acute kidney injury. Intensive care medicine 2017; 43: 1198-1209.
About SphingoTec
SphingoTec GmbH ("SphingoTec"; Hennigsdorf near Berlin, Germany) is a commercial-stage diagnostic company focusing on innovative critical care biomarkers for diagnosing, predicting, and monitoring acute medical conditions. SphingoTec’s innovative markers are made 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.
About penKid
Proenkephalin A 119-159 (penKid) is a blood-based biomarker for assessing kidney function in acute and critical conditions. The biomarker offers a blood-based alternative for the complex and time-consuming in vivo measurement of true glomerular filtration rate (GFR). PenKid is independent of common comorbidities (e.g., hypertension and diabetes) and the frequently occurring inflammation in critically ill patients. Rising penKid blood levels predict acute kidney injury earlier than today’s standard of care, and decreasing penKid blood levels indicate the improvement of kidney function, even under dialysis. Scientific evidence shows that penKid also reflects kidney function in children, representing a potential biomarker for pediatric AKI.
Media contact:
Ruxandra Lenz
Head of Marketing and Communication
SphingoTec GmbH
Neuendorfstr. 15 A
16761 Hennigsdorf
Tel. +49-3302-20565-0
• 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