Karin Gerritsen, MD, PhD, internist-nephrologist and clinical scientist at University Medical Center (UMC) Utrecht

Karin G. Gerritsen, MD, PhD

A portable sorbent hemodialysis system met its prespecified adequacy threshold for single-pool Kt/V, with no serious adverse device effects, in the first 2 phases of the pivotal RENEW-HD trial.¹

Karin Gerritsen, MD, PhD, of the Department of Nephrology and Hypertension at University Medical Center (UMC) Utrecht and senior author of the study, discussed the data from the 

American Society of Nephrology (ASN) Kidney Week 2026

 in Denver, Colorado. Fluid, electrolyte, and acid-base parameters remained generally stable in the single-arm, open-label trial, and investigators plan to lower dialysate calcium before evaluating more autonomous use.

RENEW-HD: Portable Hemodialysis Data, With Karin Gerritsen, MD, PhD

 that the system was developed in response to “the strong unmet need among dialysis patients for more flexibility, more autonomy, a bit more freedom.”

How the Neokidney Sorbent System Regenerates Dialysate

Conventional hemodialysis requires substantial infrastructure and water, which limits patient mobility.¹ Standard systems use ≥30 L of dialysate per session, and treatment typically runs 4 hours, 3 times per week.² According to Gerritsen, other low-flow home systems still run dialysate in a single pass, which keeps fluid volumes high.

The roughly 13 kg Neokidney instead regenerates 4.5 L of dialysate through sorbents in a closed loop. Urease in the cartridge breaks down urea, and the released ammonium is captured by zirconium phosphate. The device runs at a fixed dialysate flow of 300 mL/min and does not require a connection to water supply or drainage.

RENEW-HD is a pivotal, prospective, open-label, single-arm investigation in adults on maintenance hemodialysis at 4 European centers. In phase 1, 4 participants received assisted in-center treatment with the Neokidney for up to 11 sessions over 3 weeks.

In phase 2, participants received assisted in-center treatment for up to 30 days, at 4 to 7 two-hour sessions per week, with a target of 500 sessions. The primary efficacy endpoint was mean single-pool Kt/V (spKt/V), with adequate performance defined as a lower bound of the 2-sided 95% confidence interval (CI) ≥0.60. Additional outcomes included serious adverse device effects (SADEs), vital and biochemical parameters, and ultrafiltration accuracy.

Neokidney Kt/V and Ultrafiltration Results

As of August 31, 2026, 29 participants had completed 474 sessions, 95% of those planned for phases 1 and 2.¹

In the data presented at the meeting, mean spKt/V was 0.74 per 2-hour treatment, with the lower bound of the CI above 0.60. Gerritsen reported a mean weekly standardized Kt/V of 2.19, not accounting for residual kidney function. Ultrafiltration volumes calculated from body weight agreed with device-reported volumes in 95% of cases.

Vital parameters and blood biochemistry, including sodium and bicarbonate, remained generally stable over the 4-week treatment period.¹ Gerritsen noted that sodium declined slightly, which investigators attributed to a shift toward each patient’s individual sodium set point, as dialysate sodium equilibrates with plasma. Phosphate rose slightly while reduction ratios stayed high, which investigators believe may reflect increased protein intake; this is still under investigation.

Neokidney Safety Findings and Sorbent Exhaustion Alarms

No SADEs or device deficiencies with the potential to cause a serious adverse event occurred, and no hyperammonemia was observed in any of the 474 sessions.¹ In the abstract, sorbent exhaustion occurred once, at the end of a session in which estimated urea removal exceeded the system’s specified capacity, and was correctly detected by the device.

In the updated data presented at the meeting, Gerritsen reported 5 sessions that ended early when cartridge exhaustion triggered an ammonium alarm, which she described as the intended safety response. In each case, urea removal exceeded the cartridge specifications and no hyperammonemia occurred. Two additional sessions ended early near their scheduled end because of system errors after abrupt patient movement.

Dialysate Calcium Elevations Ahead of Phase 3

The most notable adverse device effect involved calcium. Gerritsen reported that ionized calcium rose above 1.5 mmol/L in 3 patients without symptoms, and 1 patient was withdrawn after 2 weeks. In most others, predialysis calcium rose gradually before stabilizing at approximately 1.3 mmol/L.

Investigators traced this to a dialysate calcium concentration >1.6 mmol/L and plan to adjust it for phase 3. Three patients also reported taste disturbances, the cause of which is being investigated.

Next Step: Autonomous Use and Home Certification

Investigators concluded that the dialysis dose was consistent with current adequacy targets, supporting the feasibility of the system.¹ The phase 1 and 2 data will support an application for CE certification for in-center use in Europe. Phase 3, expected to begin by the end of 2026, will evaluate more autonomous use across approximately 500 additional sessions to support certification for home use.

“We think these results provide a solid base to proceed to the third stage, the autonomous use of the device,” Gerritsen said.

Editor’s Note: RENEW-HD was funded by Nextkidney B.V.

Bolhuis DP, Bach D, Bluechel C, et al. Efficacy and safety of the Neokidney portable hemodialysis system: preliminary phase 1 and 2 results of the RENEW-HD trial. Late-breaking abstract presented at: American Society of Nephrology Kidney Week 2026; October 21-25, 2026; Denver, CO. doi:10.1681/ASN.2026yrjf6rv2

UMC Utrecht. Patients test a portable artificial kidney at home for the first time. Published January 2026. Accessed October 24, 2026. 

https://research.umcutrecht.nl/news/patients-test-a-portable-artificial-kidney-at-home-for-the-first-time/

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Early RENEW-HD data support moving the 13 kg Neokidney to autonomous use testing, with dialysate calcium adjustments planned.

Karin G. Gerritsen, MD, PhD

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