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Abstract: SA-PO075

Estimation of the Total Nephron Number in Japanese Living Kidney Donors Using Combined CT Angiography and Biopsy Approach

Session Information

Category: Transplantation

  • 1802 Transplantation: Clinical

Authors

  • Sasaki, Takaya, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Tsuboi, Nobuo, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Okabayashi, Yusuke, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Kanzaki, Go, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Haruhara, Kotaro, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Koike, Kentaro, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Kobayashi, Akimitsu, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Yamamoto, Izumi, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Ogura, Makoto, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Yokoo, Takashi, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
Background

Increasing evidence suggests that individuals with low nephron number have an increased lifetime risk of renal insufficiency, thereby emphasizing the importance of evaluating total nephron number in each individual. In recent years, new methods have been described for estimating human total nephron number using a combination of image analysis and renal biopsy, though the reproducibility and accuracy of these methods remain uncertain. This study estimated total nephron number in healthy Japanese subjects using such a method.

Methods

Implantation biopsies from forty-four living kidney donors were analyzed. Using pre-donation contrast CT angiograms, transplantation donor kidneys were three-dimensionally reconstructed, and total renal cortical volume was estimated. Total nephron number was estimated based on glomerular density in biopsy specimens and total renal cortical volume. The obtained results were analyzed in relation to clinical variables and compared with those of a previously reported Japanese autopsy study.

Results

The estimated total nephron number in this cohort was 650,000±220,000 (mean±SD) per kidney. Total nephron number ranged from 280,000 to 1,220,000 per kidney (4.4-fold) and correlated directly with eGFR (r=0.328, p=0.030) and inversely with age (r=-0.355, p=0.018). The estimated total nephron number obtained in the present study was 25% less than that reported in American living kidney donors using the same procedure, and similar to that obtained in a previous Japanese autopsy study using the dissector/fractionator method (Table).

Conclusion

These results confirm the feasibility of a combined CT angiography and biopsy-based method to estimate total nephron number in humans.

Comparison of estimated total nephron number by different methods
Study populationMethodsSample sizeAge (year) (mean±SD or mean)Estimated nephron number per kidney (mean±SD or mean)
Reference
Caucasian autopsy series (normotensive)Dissector/fractionator5541901,011 ± 298,334Am J Kidney Dis 2008
Japanese autopsy series (normotensive)Dissector/fractionator964.1 ± 6.3640,399 ± 160,016 JCI insight 2017
American kidney donors (92.7% Caucasian)CT angiogram and biopsy163843.2 ± 11.7873696J Am Soc Nephrol 2017
Japanese kidney donorsCT angiogram and biopsy4456.7 ± 9.5650,000 ± 220,000This study