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Kidney Week

Abstract: TH-PO134

Dimensions of Muddy Brown Granular Casts and Anthropometrics in Patients With Acute Tubular Injury

Session Information

  • AKI: Mechanisms - I
    November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Antley, Mckinley H., College of Charleston, Charleston, South Carolina, United States
  • Chalmers, Dustin, The University of Queensland Ochsner Clinical School - New Orleans, New Orleans, Louisiana, United States
  • Ramanand, Akanksh, The University of Queensland Ochsner Clinical School - New Orleans, New Orleans, Louisiana, United States
  • Velez, Juan Carlos Q., The University of Queensland Ochsner Clinical School - New Orleans, New Orleans, Louisiana, United States
  • Janech, Michael G., College of Charleston, Charleston, South Carolina, United States

Group or Team Name

  • Ochsner Nephrology
Background

“Muddy” brown granular casts (MBGC) are identifiable by microscopic examination of the urinary sediment (MicrExUrSed). The presence of MBGC is pathognomonic for acute tubular injury (ATI). Although, MBGC have been noted for years, there are no reports regarding their length nor width. The objective of this study was to measure MBGC using images obtained by light microscopy and correlate them to patient anthropometric and urine chemistry values.

Methods

At Ochsner Medical Center, data from patients seen in nephrology consultation who had a urine specimen subjected to MicrExUrSed is prospectively collected. Representative images from each case are routinely stored. A subset of patients with diagnosis of ATI as evidenced by visualization of abundant MBGC (>30% low power fields) were sampled. Images were obtained under bright field microscopy at 400x magnification with an accompanying stage micrometer for external calibration and were measured using ImageJ. Length was measured at 3 sections parallel to the longitudinal axis. Width was measured in 6 sections parallel to the transverse axis. A minimum of 15 MBGC were measured per specimen. Spearman rank test was performed to examine correlations between MBGC width and demographics, anthropometrics, and urine chemistry.

Results

height 1.70 ± 0.1 m, mean BMI 32 ± 7. Mean MBGC length was 98.1 ± 42.1 (range 39–72) µm. Mean width was 33.5 ± 12.3 (range 9–110) µm. Based on a previous report of cortical tubular diameters, MBGC width corresponded well with the median reported range of 30–40 µm. MBGC width did not correlate with age, race, sex, BMI or weight. Height was positively correlated with mean MBGC width (rho = 0.48, p<0.05). There was no significant correlation between mean MBGC width and urine sodium, potassium, chloride, creatinine, urea nitrogen, pH, specific gravity or total protein.

Conclusion

This is the 1st study reporting dimensions of MBGC from patients with ATI. MBGC length is highly variable compared to width. Because kidney size is known to correlate with height, the correlation of MBGC with height suggests that nephron size influences MBGC width. Clinical implications of these observations require further study.

Funding

  • NIDDK Support