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Updated: Jun 23, 2025
A Large Animal Model for Acute Kidney Injury by Temporary Bilateral Renal Artery Occlusion
Published on: February 2, 2021
Dimensions of muddy brown granular casts in patients with acute tubular injury
McKinley H Antley1, Dustin Chalmers2, Akanksh Ramanand2
1Department of Biology, College of Charleston, 66 George Street, Charleston, SC 29424, USA.
Background:
The presence of "muddy" brown granular casts (MBGC) in the urine sediment 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 investigate associations with clinically relevant parameters.
Methods:
Patients with diagnosis of ATI as evidenced by visualization of abundant MBGC (>30% low power fields) were sampled. Bright-field images were measured using ImageJ. Twenty-five patients were included: 44% women; median age 64 yrs; 52% white, 36% black. Mean MBGC width (n = 350) was 34.4 ± 13.1 µm (range: 9 to 110 µm).
Results:
Mean MBGC length was 98.7 ± 42.7 µm (range: 33 to 317 µm). Based on a previous report of cortical tubular diameters, MBGC width corresponded well with the median reported range. MBGC width was positively correlated with patient height (ρ=0.41, p=0.04), and length was positively correlated with fractional excretion of sodium (ρ=0.57. p=0.02) and urine chloride concentration (ρ=0.90, p=0.001). Mean MBGC length was negatively correlated with age (ρ=-0.47, p=0.02) and urine phosphate concentration (ρ=-0.72, p=0.03). There were no differences between cases that required renal replacement therapy (RRT, n =10) and those that did not require RRT (n=15).
Conclusion:
This is the first study reporting dimensions of MBGC from cases with ATI. Clinical implications of these observations require further study.
Insights
This study measured "muddy" brown granular casts (MBGC) in acute tubular injury (ATI) patients, finding correlations between MBGC dimensions and clinical factors like height and urine chemistry. These measurements offer new insights into ATI.
Area of Science:
- Nephrology
- Uropathology
- Medical Diagnostics
Background:
- "Muddy" brown granular casts (MBGC) are pathognomonic for acute tubular injury (ATI).
- Previous research has not quantified MBGC dimensions.
- Understanding MBGC morphology may provide diagnostic and prognostic information.
Purpose of the Study:
- To measure the length and width of MBGC in patients with ATI.
- To explore associations between MBGC dimensions and clinical parameters.
Main Methods:
- Light microscopy images of MBGC from 25 ATI patients were analyzed using ImageJ.
- Measurements included MBGC width (n=350) and length.
- Patient data on demographics, urine chemistry, and renal replacement therapy (RRT) were collected.
Main Results:
- Mean MBGC width was 34.4 ± 13.1 µm; mean length was 98.7 ± 42.7 µm.
- MBGC width correlated positively with patient height.
- MBGC length correlated with fractional excretion of sodium, urine chloride, and inversely with age and urine phosphate.
Conclusions:
- This study provides the first quantitative data on MBGC dimensions in ATI.
- MBGC dimensions show correlations with specific clinical and laboratory findings.
- Further research is needed to determine the clinical significance of these measurements.
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