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AKI Staging (KDIGO)Anion Gap + Delta-Delta CKD Stage (KDIGO)Creatinine Clearance Electrolyte & Free Water FENa FEUrea KFRE — Kidney Failure Risk Kt/V Dialysis Sodium Correction UACR UPCR Urea Reduction Ratio (URR) Calculator Uric Acid & FEUA Urinary Anion Gap Winter's Formula eGFR (CKD-EPI)

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Recent Journal Updates

Alzheimers & DementiaJun 8, 2026

Differential associations of plasma biomarkers with Alzheimer's disease and small vessel disease: A multimodal imaging study

Clinical Context

We think this has broad domain relevance to FENa — Fractional Excretion of Sodium.

British J Clinical PharmacologyJun 6, 2026

6‐Mercaptopurine metabolic profiles and clinical outcomes in TPMT and NUDT15 phenotypes during maintenance therapy for Thai paediatric acute lymphoblastic leukaemia

Clinical Context

We think this has broad domain relevance to FENa — Fractional Excretion of Sodium.

WHO NewsJun 5, 2026

Africa CDC and WHO launch joint continental Ebola response plan

Clinical Context

We think this has broad domain relevance to FENa — Fractional Excretion of Sodium.

FENa

FENa Calculator

Fractional Excretion of Sodium

Plasma Values

Sodium (PNa) mmol/L

Creatinine (PCr) mg/dL

Urine Values

Sodium (UNa) mmol/L

Creatinine (UCr) mg/dL

Unreliable in the presence of diuretics.

Fractional Analyst

Enter paired plasma and urine chemistries to determine renal etiology.

Guidelines & Evidence

Verified

Last Review: 2026

When to Use

When to Use

Differential diagnosis of Acute Kidney Injury (AKI) in oliguric patients (urine output < 400 mL/day).

Distinguishing prerenal azotemia (hypoperfusion) from intrinsic renal injury, specifically Acute Tubular Necrosis (ATN).

Assessing tubular integrity in the setting of rising serum creatinine.

Required Parameters

Requires simultaneous (paired) spot urine and serum samples for Sodium (Na) and Creatinine (Cr).

When Not to Use

Non-oliguric AKI: Accuracy is significantly lower if urine output is preserved.

Recent diuretic use (within 24 hours): Diuretics inhibit Na reabsorption, falsely elevating FENa.

Chronic Kidney Disease: Damaged tubules in CKD have a baseline defect in Na handling, making the 1% threshold unreliable.

Related Scores in Practice

In clinical practice, this assessment is frequently evaluated alongside other validated measures. Depending on the patient's presentation and specific diagnostic requirements, you may also need to utilize the FEUrea, AKI Staging (KDIGO) or the Urinary Anion Gap to formulate a comprehensive care plan.

Last Comprehensive Review: 2026

Related Nephrology Tools

Uric Acid & FEUA

KFRE — Kidney Failure Risk

Urea Reduction Ratio

Urinary Anion Gap

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