Kidney Week

Abstract: FR-PO0404

Correlation of Urinary Electrolyte Excretion Fractions with AKI Severity in Patients in the Intensive Care Unit

Session Information

• AKI: Biomarkers, Diagnostics, and Risk Prediction
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

• 102 AKI: Clinical, Outcomes, and Trials

Authors

• De La Torre, Juana Citlali, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Mexico City, CDMX, Mexico

Juana Citlali De La Torre, DM

• Alamilla-Sanchez, Mario, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Mexico City, CDMX, Mexico

Mario Alamilla-Sanchez, MD, MSc

• Ulloa Galvan, Victor Manuel, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Mexico City, CDMX, Mexico

Victor Manuel Ulloa Galvan, MD

• Ruiz Rivera, Fani Guadalupe, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Mexico City, CDMX, Mexico

Fani Guadalupe Ruiz Rivera, PhD

• Salazar Hurtado, Jorge David, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Mexico City, CDMX, Mexico

Jorge David Salazar Hurtado, MD

• Gonzalez-Fuentes, Carolina, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Mexico City, CDMX, Mexico

Carolina Gonzalez-Fuentes, MD, MSc

Background

Acute Kidney Injury (AKI) ipresents in up to 70% of patients in the Intensive Care Unit (ICU). The most commonly used biomarker is serum creatinine, which has proven to be inadequate. Proximal tubular secretion function is infrequently measured during an AKI episode.

Methods

A cross-sectional study was conducted. The objetive of the study was to identify if urine electrolyte excretation correlates with the severity of acute kidney injury.

Results

Analysis of urinary indices documented a median fractional excretion of sodium (FeNa) reported at 1.49 (0.40–4.39). The mean fractional excretion of phosphorus (FeP) was 30.52 ± 24. The mean FeMg was 14.48 ± 21.8. The fractional excretion of calcium (FeCa) showed a median of 1.21 (0.41–3.67). The urinary potassium-to-urinary creatinine ratio (Ku/CrU) was evaluated, with a median of 13.03 (9.21–15.00) mEq/g. creatinine-to-serum creatinine ratio (UCr/SCr), a median of 25.9 (12.48–48.5) mg/dL The protein-to-creatinine index (PCI) showed a median of 0.45 (0.17–1.25) mg/mg. Urinary beta-2 microglobulin showed a median of 0.14 (0.02–0.37) mg/L, Correlation with renal recovery, FeNa >3: OR 1.42 (0.56–3.6) FeP >15: OR 1.36 (0.46–4.02), FeCa >2: OR 1.02 (0.35–2.66), FeMg >4: OR 0.97 (0.32–2.7), PCI >0.5: OR 0.12 (0.031–0.148), urinary osmolarity was 334.5 it corraletes with kidney recovery with a AUC curve with 0.71 with a sensibility 0.86 and specificity of 0.7.

Conclusion

In patients with AKI, tubular function tends to manifest through urinary losses of sodium, phosphorus, and magnesium, as well as a failure to reabsorb urinary beta-2 microglobulin. However, the alteration of these urinary indices does not increase the risk of severity for this condition, as part of the analysis we found that urinary osmolarity corralates with concentration capacity during an AKI can be a predictive marker of kidney function recovery.

AUC Osmolarity and kidney recovery