Increased urinary excretion of kynurenic acid is associated with non-recovery from acute kidney injury in critically ill patients.

Aregger, Fabienne; Uehlinger, Dominik; Fusch, Gerhard; Bahonjic, Aldin; Pschowski, Rene; Walter, Michael; Schefold, Joerg C. (2018). Increased urinary excretion of kynurenic acid is associated with non-recovery from acute kidney injury in critically ill patients. BMC nephrology, 19(1), p. 44. BioMed Central 10.1186/s12882-018-0841-5

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Acute kidney injury (AKI) is often observed in critically ill patients and is associated with high morbidity and mortality. Non-recovery from AKI has a negative impact on the prognosis of affected patients and early risk stratification seems key to improve clinical outcomes. We analyzed metabolites of a conserved key inflammatory pathway (i.e. tryptophan degradation pathway) in serial urine samples of patients with AKI.


One hundred twelve ICU patients with AKI were included in a prospective observational analysis. After exclusion criteria, 92 patients were eligible for analysis. Serial urine samples were collected and tryptophan levels including key tryptophan metabolites were measured using tandem mass spectrometry.


Sixty-seven patients recovered in the first 7 days of AKI (early recovery, ER) whereas n = 25 had late-/non-recovery (LNR). Urinary concentrations of tryptophan, kynurenine, 3-OH anthranillic acid, serotonine, and kynurenine/tryptophan were significantly lower in LNR patients. In contrast, creatinine normalized excretion of kynurenic acid (KynA) was substantially increased in LNR patients (7.59 ± 6.81 vs. 3.19 ± 3.44 (ER) μmol/mmol, p <  0.005). High urinary KynA excretion was associated with higher RIFLE class, longer AKI duration, increased need for RRT, and 30-day mortality. Logistic regression revealed KynA as the single most important predictor of renal recovery on days 1 and 2 of AKI.


Increased urinary levels of kynurenic acid, a key inflammatory metabolite of the tryprophan degradation pathway, are associated with adverse renal and clinical outcomes in critically ill patients with AKI. Urinary KynA may serve as an early risk stratificator in respective patients with AKI.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Dermatology, Urology, Rheumatology, Nephrology, Osteoporosis (DURN) > Clinic of Nephrology and Hypertension
04 Faculty of Medicine > Department of Intensive Care, Emergency Medicine and Anaesthesiology (DINA) > Clinic of Intensive Care

UniBE Contributor:

Uehlinger, Dominik and Schefold, Joerg C.


600 Technology > 610 Medicine & health




BioMed Central




Mirella Aeberhard

Date Deposited:

18 Apr 2018 09:20

Last Modified:

25 Oct 2019 07:19

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

IDO Inflammation Intensive care unit Kynurenines Renal failure Renal recovery Tryptophan metablism




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