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Kidney Week

Abstract: PO0053

Urinary Waxy Casts Are Associated with Persistence of AKI Requiring Dialysis

Session Information

Category: Acute Kidney Injury

  • 102 AKI: Clinical, Outcomes, and Trials

Authors

  • Rivera, Maria Soledad, Ochsner Clinical School - University of Queensland, New Orleans, Louisiana, United States
  • Varghese, Vipin, Ochsner Clinical School - University of Queensland, New Orleans, Louisiana, United States
  • Ramanand, Akanksh, Ochsner Clinical School - University of Queensland, New Orleans, Louisiana, United States
  • Alalwan, Ali Abdulrazzaq, Department of Nephrology, Ochsner Clinic Foundation, New Orleans, Louisiana, United States
  • Velez, Juan Carlos Q., Ochsner Clinical School - University of Queensland, New Orleans, Louisiana, United States

Group or Team Name

  • Ochsner Nephrology
Background

Waxy casts (WxCs) can be identified during microscopic examination of the urinary sediment (MicrExUrSed) and they have been classically linked to chronic kidney disease (CKD). We previously shown that WxCs predict severity of acute kidney injury (AKI). Thus, we hypothesized that WxCs may inform about duration and persistence of AKI and AKI requiring renal replacement therapy (AKI-RRT).

Methods

We conducted a prospective observational study in patients seen in inpatient nephrology consultation with AKI stage ≥ 2 (AKIN) over 2.5 years. On the day of consult, MicrExUrSed was performed to determine the percentage of low power fields with WxCs. The outcome measures were persistence of need for RRT at the time of hospital discharge (AKI-RRT-Persist) and ≥ 50% rise in serum creatinine (sCr) from baseline at the time of hospital discharge (AKI-Persist).

Results

Urine specimens from 286 patients [median age 60 (20 – 88), 37% women] were assessed. The etiology of AKI (de novo AKI 67%, AKI on CKD 33%) was ischemic ATI (47%), toxic ATI (9%), ischemic/toxic ATI (11%) or other (33%). WxCs were found in 85 patients (30%), 61 (72%) of which had de novo AKI. Median sCr for those with WxCs was 3.5 (0.9 – 22.0)mg/dL and 3.1 (0.9 – 12.5) mg/dL for those without WxCs (p=0.12). AKI-RRT at any point during the course of AKI was seen in 45% (38/85) of those with WxCs compared to 32% (54/201) of those without WxCs (p=0.043). There was a greater risk for AKI-RRT-Persist for those withWxCs [15.3% vs 7.5%, odds ratio (OR): 2.2, CI 1.1 – 4.9, p=0.046)]. Presence and abundance of WxCs were also associated with a greater risk for AKI-Persist [62% (94/152), 75% (45/60), 81% (29/36) and 93% (13/14), for those with no WxC, any WxC, >10% WxCs and >50% WxCs , respectively; chi-square for trend, p=0.014].

Conclusion

In patients with AKI, the presence and abundance of WxCs are associated with a greater risk for persistent need for RRT and persistent increase in sCr at the time of hospital discharge. These findings suggest that WxCs inform about the severity of AKI and the timeline of significant AKI recovery.