Comparison between fractional excretion of sodium and fractional excretion of urea in differentiating prerenal from renal azotemia in circulatory shock

Yassin, Abdel Rahman; Sherif, Hossam; Mousa, Ahmed; Esmat, Amr Y.

doi:10.1016/j.ejccm.2013.05.001

Cited by 5 publications

(4 citation statements)

References 16 publications

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“…Interestingly, RFI seems to be a little known but helpful index that is easy to obtain in any hospital. In contrast to previous data, certain co-comorbidities and co-medications did not have a significant impact on the examined parameters and indices ( 32 , 33 ). This is important since drugs targeting the renin–angiotensin–aldosterone-system are very common, making U Na , U SG and RFI useful means to differentiate prerenal AKI and ATN in hospitalized patients.…”

Section: Discussioncontrasting

confidence: 99%

Evaluation of simple diagnostic parameters in acute kidney injury in hospitalized patients—diagnostic recommendations for non-nephrologists

Buckenmayer,

Siebler,

Haas

2023

Intern Emerg Med

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Acute kidney injury (AKI) is very common in hospitalized patients, affecting patient’s mortality and morbidity. Major causes are prerenal AKI and acute tubular necrosis (ATN). Even though a variety of parameters/indices exist, their reliability and practicability are controversial: in fact, there is a need for a simple diagnostic approach for AKI in in-patients with parameters easily obtained in any hospital. The objective of the study was: (1) to assess reliability of simple laboratory parameters/indices to differentiate pre-/intrarenal AKI; (2) to evaluate the most reliable and feasible parameters/indices; and (3) to identify the possible impact of confounding factors. Retrospectively, in-patients with AKI hospitalized in 2020 in a university nephrology department were included. Spot urine and 24-h collection urine was analyzed with urine sodium (UNa), urine specific gravity (USG), fractional excretion of sodium (FENa), fractional excretion of urea (FEUrea), urine osmolality (UOsm), urine to plasma creatinine ratio (UCr/PCr) and renal failure index (RFI). Overall, 431 patients were included. UNa, UOsm, USG and RFI showed high specificity > 85% for prerenal AKI, UNa and RFI provided good specificity for ATN. Loop diuretics, ACE inhibitors/AT1 blockers or pre-existing chronic kidney disease had no impact. In patients with AKI, UNa, USG and RFI: (1) proved to be very specific for prerenal AKI and showed high sensitivity for ATN; (2) can be easily determined using serum and spot urine; and (3) are not confounded by medication or comorbidities. These parameters/indices are helpful to identify the aetiology of AKI and to guide therapy, thereby improving patients’ safety and outcome.

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Section: Discussioncontrasting

confidence: 99%

Evaluation of simple diagnostic parameters in acute kidney injury in hospitalized patients—diagnostic recommendations for non-nephrologists

Buckenmayer,

Siebler,

Haas

2023

Intern Emerg Med

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“…Although the FENa test should be done early in the disease before the final diagnosis, six studies (21,23,26,29,39,40) were unclear if the index test was interpreted separately from the reference standard. In five (9,21,23,26,29) of the included studies, we were uncertain whether the interval between the index test and the reference standard was appropriate. Finally, most of the studies' patients were hospitalized, which may affect the external validity of our findings.…”

Section: Discussionmentioning

confidence: 99%

“…All of the studies used the clinical responsiveness to fluids as a reference standard, and two of them included patients with HRS and AKI (19,24,25). Additionally, four studies (6,7,21,26) used histopathologic examination other than response to fluid expansion, whereas nine studies (4,9,20,(22)(23)(24)(27)(28)(29)(30) supported their findings using microscopic urine analysis.…”

Section: Study Selection and General Informationmentioning

confidence: 99%

“…All studies included hospitalized patients or patients in the intensive care unit, except for one study that did not report patients' settings (6) and one study that enrolled patients in the emergency room (18). All but five studies (18,(21)(22)(23)(24) used the 1% threshold. In addition, we obtained the necessary data to apply the 1% threshold in one study (22).…”

Section: Study Selection and General Informationmentioning

confidence: 99%

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Diagnostic Performance of Fractional Excretion of Sodium for the Differential Diagnosis of Acute Kidney Injury

Abdelhafez

Nayfeh

Atieh

et al. 2022

CJASN

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Background and objectivesAKI is classified as prerenal, intrinsic, and postrenal. Prerenal AKI and intrinsic AKI represent the most common causes for AKI in hospitalized patients. This study aimed to examine the accuracy of the fractional excretion of sodium for distinguishing intrinsic from prerenal AKI.Design, setting, participants, & measurementsWe searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, the Cochrane Library, and Scopus for all available studies that met the criteria until December 31, 2021. We included studies that evaluated fractional excretion of sodium in differentiating AKI etiologies in adults, whereas studies that did not have sufficient data to extract a 2×2 table were excluded. We assessed the methodologic quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool and extracted the diagnostic accuracy data for all included studies. We conducted a meta-analysis using the bivariate random effects model. We performed subgroup analysis to investigate sources of heterogeneity and the effect of the relevant confounders on fractional excretion of sodium accuracy.ResultsWe included 19 studies with 1287 patients. In a subset of 15 studies (872 patients) that used a threshold of 1%, the pooled sensitivity and specificity for differentiating intrinsic from prerenal AKI were 90% (95% confidence interval, 81% to 95%) and 82% (95% confidence interval, 70% to 90%), respectively. In a subgroup of six studies (511 patients) that included CKD or patients on diuretics, the pooled sensitivity and specificity were 83% (95% confidence interval, 64% to 93%) and 66% (95% confidence interval, 51% to 78%), respectively. In five studies with 238 patients on diuretics, the pooled sensitivity and specificity were 80% (95% confidence interval, 69% to 87%) and 54% (95% confidence interval, 31% to 75%), respectively. In eight studies with 264 oliguric patients with no history of CKD or diuretic therapy, the pooled sensitivity and specificity were 95% (95% confidence interval, 82% to 99%) and 91% (95% confidence interval, 83% to 95%), respectively.ConclusionsFractional excretion of sodium has a limited role for AKI differentiation in patients with a history of CKD or those on diuretic therapy. It is most valuable when oliguria is present.

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Updates in Nephrology for the Hospitalist

Kandalam

Malone²,

Vu³

et al. 2022

Clinical Approaches to Hospital Medicine

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Comparison between fractional excretion of sodium and fractional excretion of urea in differentiating prerenal from renal azotemia in circulatory shock

Cited by 5 publications

References 16 publications

Evaluation of simple diagnostic parameters in acute kidney injury in hospitalized patients—diagnostic recommendations for non-nephrologists

Evaluation of simple diagnostic parameters in acute kidney injury in hospitalized patients—diagnostic recommendations for non-nephrologists

Diagnostic Performance of Fractional Excretion of Sodium for the Differential Diagnosis of Acute Kidney Injury

Updates in Nephrology for the Hospitalist

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