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Observational Study
. 2025 May 26;29(1):214.
doi: 10.1186/s13054-025-05452-1.

Spontaneous diuresis in combination with furosemide stress test (SD-FST) as predictor for successful liberation from kidney replacement therapy: a prospective observational study

Lorenz Weidhase #  1 , Stephanie Wille #  2 , Helene Foede  2 , Fanny Gilch  2 , Meinhard Mende  3 , Christina Scharf-Janßen  4 , Sirak Petros  2 , Jonathan de Fallois  5
Affiliations
Observational Study

Spontaneous diuresis in combination with furosemide stress test (SD-FST) as predictor for successful liberation from kidney replacement therapy: a prospective observational study

Lorenz Weidhase et al. Crit Care. .

Abstract

Background: The optimal time for initiating kidney replacement therapy (KRT) in acute kidney injury (AKI) has been extensively studied in recent years. In contrast, there are currently insufficient data on the best time to discontinue KRT. One diagnostic option to unmask tubular reserve and indirectly estimate the glomerular filtration rate is the furosemide stress test (FST).

Methods: We conducted a prospective, observational single-center trial. A FST was carried out in patients who developed spontaneous diuresis (SD) during ongoing KRT with a urine output of at least 400 ml in 24 h without any diuretic therapy. A positive FST was defined with urine output > 200 ml within 2 h following intravenous furosemide application. Follow-up was performed for 7 days and the need to restart KRT was assessed daily.

Results: After 100 patients were enrolled in the trial, 98 patients were eligible for further evaluation. 76 patients were FST-positive, while 22 patients were FST-negative. Resumption of KRT within the 7-day follow-up was required in only 14.5% of the FST-positive, but 72.7% of the FST-negative patients (p < 0.001). The urine output after FST was also significantly associated with successful release from KRT (AUC 0.87; p < 0.001).

Conclusions: In critically ill patients with recovery of SD > 400ml/d during ongoing KRT, the FST helps to identify patients who can be successfully liberated from KRT. By detecting the tubular reserve using FST, the possibility of short-term kidney recovery after AKI can be estimated.

Trial registration: German Clinical Trials Registry (DRKS00030560); date of registration 18/11/2022. https://drks.de/search/de/trial/DRKS00030560 .

Keywords: Acute kidney injury (AKI); Furosemide stress test (FST); Kidney replacement therapy (KRT); Recovery of kidney function.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This study was approved by the local Institutional Review Board at the Medical Faculty of the University of Leipzig (171/22-ek). Informed consent to participate was obtained from all of the participants in the study. Patients under 18 years of age were excluded. All experiments were performed in accordance with relevant guidelines and regulations. Consent for publication: Not applicable. Competing interests: Lorenz Weidhase was involved in scientific projects funded by Fresenius Medical Care Deutschland GmbH (Else-Kröner-Straße 1, D-61352 Bad Homburg, Germany) and CytoSorbents Europe GmbH (Müggelseedamm 131, Berlin, Germany). Christina Scharf got speaker honoraria by CytoSorbents Europe GmbH. The remaining authors have disclosed that they do not have any conflicts of interest.

Figures

Fig. 1
Fig. 1
Recruitment flowchart of patients with recovery spontaneous diuresis during ongoing kidney replacement therapy with a urine output of at least 400 ml in 24 h. FST Furosemide stress test, ICU Intensive care unit
Fig. 2
Fig. 2
Successful liberation from kidney replacement therapy within 7 days after recovery of spontaneous diuresis and furosemide stress test. Data are presented graphically as a bar chart. All patients (n) had spontaneous diuresis (SD) of at least 400 ml/24 h before the furosemide stress test (FST), KRT Kidney replacement therapy
Fig. 3
Fig. 3
Diuresis and successful liberation from kidney replacement therapy within 7 days. Data are presented graphically as ROC curve. Thick continuous line: Diuresis 2 h after FST and successful liberation from KRT within 7 d (AUC: 0.871, CI 0.799–0.943). Thick dashed line: SD of the previous day (24 h) and successful weaning from KRT within 7 d (AUC 0.542; CI 0.409–0.674). Thin dashed line: diagonal reference line SD Spontaneous diuresis, FST Furosemide stress test, KRT Kidney replacement therapy
See this image and copyright information in PMC

References

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