Diagnostic performance of a point-of-care saliva urea nitrogen dipstick to screen for kidney disease in low-resource settings where serum creatinine is unavailable

Abstract

BackgroundKidney disease is prevalent in low-resource settings worldwide, but tests for its diagnosis are often unavailable. The saliva urea nitrogen (SUN) dipstick is a laboratory and electricity independent tool, which may be used for the detection of kidney disease. We investigated the feasibility and performance of its use in diagnosing kidney disease in community settings in Africa.MethodsAdult patients at increased risk of kidney disease presenting to three community health centres, a rural district hospital and a central hospital in Malawi were recruited between October 2016 and September 2017. Patients underwent concurrent SUN and creatinine testing at enrolment, and at 1 week, 1 month, 3 months and 6 months thereafter.ResultsOf 710 patients who presented at increased risk of kidney disease, 655 (92.3%) underwent SUN testing at enrolment, and were included (aged 38 (29-52) years, 367 (56%) female and 333 (50.8%) with HIV). Kidney disease was present in 482 (73.6%) patients and 1479 SUN measurements were made overall. Estimated glomerular filtration rate (eGFR) correlated with SUN (r=−0.39; p<0.0001). The area under the receiver operating characteristics curve was 0.61 for presenting SUN to detect acute or chronic kidney disease, and 0.87 to detect severe (eGFR <15 mL/min/1.73 m2) kidney disease (p<0.0001; sensitivity 82.3%, specificity 81.8%, test accuracy 81.8%). In-hospital mortality was greater if enrolment SUN was elevated (>test pad #1) compared with patients with non-elevated SUN (p<0.0001; HR 3.3 (95% CI 1.7 to 6.1).ConclusionsSUN, measured by dipstick, is feasible and may be used to screen for kidney disease in low resource settings where creatinine tests are unavailable.

Malaria-Associated Acute Kidney Injury in African Children: Prevalence, Pathophysiology, Impact, and Management Challenges

“…150 SUN has been tested in several adult populations, including populations in lowresource settings, where SUN had good performance of identifying AKI with areas under the ROC curve >0.80. [151][152][153][154][155] There is now evidence that SUN can Neutrophil gelatinase-associated lipocalin (NGAL) is a 25 kDa glycoprotein expressed and secreted by kidney tubular cells and is considered an early biomarker of kidney injury. 157 Recently, a lateral-flow test strip was developed by BioPorto that can facilitate rapid quantitation of urinary NGAL (uNGAL) in resource-limited settings.…”

Assessment of oral and overall health parameters using the SillHa Oral Wellness System

“…Studies have reported that the presence of such ammonia producing bacteria may be beneficial and is correlated with decreased caries incidence, as these species aid in maintaining a more alkaline oral environment that is less prone to demineralization 8 . The source of these metabolic substrates can vary, however, coming from a combination of diet, secretion through salivary glands, or poor oral hygiene 9,10 . As for urea secreted through salivary glands, it can be associated with proteinaceous diets or systemic health conditions 9,10 .…”

“…The source of these metabolic substrates can vary, however, coming from a combination of diet, secretion through salivary glands, or poor oral hygiene 9,10 . As for urea secreted through salivary glands, it can be associated with proteinaceous diets or systemic health conditions 9,10 .…”

“…These results are significant because research shows that >30% of adults with diabetes have kidney disease 20 , and patients with cancer histories have a bidirectional, increased incidence of kidney disease 21 . The potential link between cancer and diabetes and elevated ammonia results is possibly the increase in blood urea nitrogen associated with kidney disease that results in a concomitant increase in salivary urea nitrogen 10 . As discussed above, urea is a substrate for ammonia producing bacteria, which could explain the elevation of ammonia results in these two groups.…”

Pragmatic Recommendations for the Prevention and Treatment of Acute Kidney Injury in Patients with COVID-19 in Low- and Middle-Income Countries

“…Salivary urea nitrogen dipstick test utilization has also proven to be an inexpensive and effective diagnostic test for AKI in sub-Saharan Africa with good specificity and sensitivity. [56][57][58] Other devices for measuring creatinine that do not require refrigeration are also being investigated. 59,60 Availability, feasibility, affordability, and safety.…”