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Abstract: FR-PO966

A Modified Ellipsoid Formula for Estimating Total Kidney Volume

Session Information

Category: Pathology and Lab Medicine

  • 1601 Pathology and Lab Medicine: Basic

Authors

  • Chao, Kristen, Angion, Uniondale, New York, United States
  • Liao, Kimberly, Angion, Uniondale, New York, United States
  • Khan, Maheen, Angion, Uniondale, New York, United States
  • Goldberg, Itzhak D., Angion Biomedica Corp., Uniondale, New York, United States
  • Narayan, Prakash, Angion Biomedica Corp., Uniondale, New York, United States
Background

Total kidney volume (TKV) informs progression of polycystic kidney disease, enables matching of donor organ to recipient, and surgical management of kidney tumors. The existing ellipse-based formula underestimates TKV by as much as 30%. We have reported (https://doi.org/10.1371/journal.pone.0190815) a modified ellipse-based formula to better estimate renal parenchymal area by extending the minor axis to the renal hilum. We sought to determine whether this modified formula better informs TKV.

Methods

PKC and Sprague-Dawley rats were used as kidney donors. True TKV was determined by the formalin displacement method. Renal thickness (t) was measured by a pair of Vernier calipers. Kidneys were then cut coronally and photographed. Treating the coronal section as an ellipse, the major axis (a), the minor axis (b) and the extender minor axis (be) were measured. TKV was calculated by entering t, a and b or be into an ellipsoid formula.

Results

Compared to true TKV, use of the existing formula underestimated calculated TKV by 14% (n=6, **, p<0.01). By contrast, there was no difference between true TKV and TKV calculated using the modified formula.

Conclusion

Use of a modified ellipsoid formula more accurately estimates TKV and has important ramifications for clinical management of polycystic kidney disease, kidney transplant, and surgical resection of renal tumors.

Treating the kidney as an ellipse and extending the minor axis into the hilum provides a better estimate of renal dimensions. The existing formula underestimated TKV significantly in healthy and PKC rats whereas use of the modified formula provided an estimate of TKV no different than true or measured TKV.

Funding

  • Private Foundation Support