Saliva Urea Nitrogen Continuously Reflects Blood Urea Nitrogen after Acute Kidney Injury Diagnosis and Management: Longitudinal Observational Data from a Collaborative, International, Prospective, Multicenter Study

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IntroductionKidney disease (KD), including acute kidney injury, is common, severe and leads to significant mortality in the developing world. However, simple tools to facilitate diagnosis and guide treatment are lacking. We studied the diagnostic performance of saliva urea nitrogen (SUN) measured by dipstick to diagnose KD in a low-resource setting.MethodsMedical admissions to a tertiary hospital in Malawi had serum creatinine tested at presentation; SUN was measured using a dipstick. Patients with serum creatinine above normal range underwent serial measurements of SUN and blood urea nitrogen for up to 7 days. Hospital outcome was recorded in all patients.ResultsA total of 742 patients were included (age 41 ± 17·3 years, 56.1% male); 146 (19.7%) had KD, including 114 (15.4%) with acute kidney injury. SUN >14 mg/dl had a sensitivity of 0.72 and a specificity of 0.87 to diagnose KD; specificity increased to 0.97 when SUN levels were combined with self-reported urine output. The diagnostic performance of SUN was comparable with the one of blood urea nitrogen (SUN area under curve, 0.82; 95% confidence interval, 0.78–0.87; blood urea nitrogen area under curve, 0.82; 95% confidence interval, 0.59–1.0). SUN >14 mg/dl on admission was an independent predictor of all-cause mortality (hazard ratio = 2.43 [95% confidence interval, 1.63–3.62]).DiscussionSUN measured by dipstick can be used to identify patients with KD in a low-resource setting. SUN is an independent predictor of mortality in this population.

Section: Discussionsupporting

confidence: 66%

“… 14 , 15 In addition, they corroborate the notion that SUN dipsticks can be used for monitoring the evolution of renal function. 22 Of note, BUN and SUN agreed well throughout all observation days, with SUN consistently reflecting BUN levels over time. Our data also corroborate previous findings of SUN levels being lower than BUN.…”

Section: Discussionmentioning

confidence: 72%

Diagnostic Performance of a Saliva Urea Nitrogen Dipstick to Detect Kidney Disease in Malawi

Evans

Calice‐Silva

Raimann

et al. 2017

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“…Baseline clinical data were recorded, and screening for kidney disease (community-acquired) was undertaken with a SCr alongside simultaneous measurement of SUN using a dipstick (Integrated Biomedical Technology, Elkhart, IN). 10 , 12 , 13 , 14 Patients were excluded if they were unable to undergo concomitant measurement of both SCr and SUN.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously demonstrated, in both developed and resource-limited settings, that the SUN dipstick demonstrates good diagnostic performance to detect kidney injury in adult medical patients with acute and chronic kidney disease, albeit with less sensitivity at lower levels of SUN. 10 , 12 , 13 , 14 In this study, we assessed the performance of the SUN dipstick to detect obstetric-related AKI in Malawi.…”

mentioning

confidence: 99%

A Salivary Urea Nitrogen Dipstick to Detect Obstetric-Related Acute Kidney Disease in Malawi

Evans

Cooke

Hemmilä

et al. 2018

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IntroductionObstetric-related acute kidney injury (AKI) is associated with adverse outcomes for mother and fetus, particularly in low-income countries. However, laboratory-independent tools to facilitate diagnosis are lacking. We assessed the diagnostic performance of a salivary urea nitrogen (SUN) dipstick to detect obstetric-related acute kidney disease in Malawi.MethodsWomen at high risk for AKI admitted to an obstetric unit in Blantyre, Malawi, were recruited between 21 September and 11 December 2015. Patients underwent serum creatinine (SCr) testing alongside measurement of SUN using a dipstick on admission, and every 48 hours thereafter if evidence of kidney disease was found.ResultsA total of 301 patients were included (mean age 25.9 years, 11% HIV positive). Of the patients, 23 (7.6%) had AKI, stage 1 in 47.8%, most commonly due to preeclampsia/eclampsia. Mean presenting SCr values were 108.8 ± 21.8 μmol/l (1.23 ± 0.25 mg/dl), 118 ± 34.45 μmol/l (1.33 ± 0.39 mg/dl), and 136.1 ± 30.4 μmol/l (1.54 ± 0.34 mg/dl) in AKI stages 1 to 3 respectively. SUN > 14 mg/dl had a sensitivity of 12.82% and a specificity of 97.33% to detect acute kidney disease; the area under the receiver operating characteristic curve was 0.551. In patients with normal SUN on admission, perinatal mortality was 11.8%, and was 25.0% if SUN was > 14 mg/dl (P = 0.18).ConclusionThe SUN dipstick was specific but insensitive when used to diagnose obstetric-related AKI. Limited biochemical derangement and low salivary urea concentrations due to physiological changes in pregnancy, as opposed to a technical limitation of the dipstick itself, are the likely reason for the lack of sensitivity in this study.

“…Although traditional dipsticks allow the assessment of renal injury by primarily testing glomerular integrity (albuminuria and/or proteinuria), newer devices have more recently been modified as markers of renal dysfunction by estimating elevated BUN using saliva, or novel blood or urine markers of tubular injury such as kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. 123,127 Recently, newer biomarkers in dipstick format have been made commercially available. 112 …”

Section: Novel Biomarkersmentioning

confidence: 99%

Acute Kidney Injury Recognition in Low- and Middle-Income Countries

Cerdá

Mohan

Garcia-Garcia

et al. 2017

Acute kidney injury (AKI) is increasingly common around the world. Because of the low availability of effective therapies and resource limitations, early preventive and therapeutic measures are essential to decrease morbidity, mortality, and cost. Timely recognition and diagnosis of AKI requires a heightened degree of suspicion in the appropriate clinical and environmental context. In low- and middle-income countries (LMICs), early detection is impaired by limited resources and low awareness. In this article, we report the consensus recommendations of the 18th Acute Dialysis Quality Initiative meeting in Hyderabad, India, on how to improve recognition of AKI. We expect these recommendations will lead to an earlier and more accurate diagnosis of AKI, and improved research to promote a better understanding of the epidemiology, etiology, and histopathology of AKI in LMICs.