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Kidney Week

Abstract: FR-OR13

Breath Ammonia Is a Useful Biomarker Predicting Kidney Function in CKD Patients

Session Information

Category: CKD (Non-Dialysis)

  • 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention


  • Tian, Ya-chung, Linkou Chang Gung Kidney Research Center and Department of Nephrology, Gueishan, Taoyuan, TW, Taoyuan, Taiwan

Chronic kidney disease (CKD) is a public health problem and its prevalence has increased worldwide; patients are commonly unaware of the condition. Early identification and immediate intervention are crucial to delay CKD progression. Finding a tool to predict kidney function without visiting hospitals is an attractive method for CKD monitoring in COVID-19 pandemic. The present study aimed to investigate whether exhaled breath ammonia measurement could be used for rapid CKD screening.


CKD patients (n=121), including CKD stage 1-5 patients, were enrolled and breath ammonia was detected. Correlation between breath ammonia and blood urea nitrogen (BUN) levels, serum creatinine levels, estimated glomerular filtration rate (eGFR) were determined. The predictive value of breath ammonia for the presence of CKD was assessed.


Correlation analysis demonstrated a good correlation between breath ammonia and blood urea nitrogen levels (R=0.756, p<0.0001), serum creatinine levels (R=0.735, p<0.0001), eGFR (R=-0.535, p<0.0001) and inversed eGFR (R=0.685, p<0.0001). Breath ammonia concentration was significantly elevated with increased CKD stage compared with the previous stage (CKD stage 1/2/3/4/5: 636±94; 1020±120; 1943±326; 4421±1042; 12781±1807 ppb, p<0.05). The receiver operating characteristic curve analysis showed an area under curve (AUC) of 0.835 (p<0.0001) for distinguishing CKD stage 1 from other CKD stages at 974 ppb (sensitivity, 69%; specificity, 95%, positive predictive value [PPV] 0.99; negative predictive value [NPV], 0.36). The AUC was 0.831 (p<0.0001) for distinguishing between patients with/without eGFR ≥60 mL/min/1.73 m2 (cut-off 1187 ppb: sensitivity, 71%; specificity, 78%; PPV, 0.84; NPV, 0.61). At 886 ppb, the sensitivity increased to 80% but the specificity decreased to 69%. For a non-life threating or non-serious CKD, breath ammonia at a cut-off concentration of 886 ppb is a good screening tool for detection of patients with potential CKD and suitable for kidney function monitoring.


Because CKD is non-life threating and breath ammonia detection was conducted in real time, inexpensive, easy to administer, and had an acceptable diagnostic accuracy, breath ammonia can be used as a good surrogate for kidney function and a reliable tool for CKD screening.


  • Government Support - Non-U.S.