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Abstract: SA-PO1112

Quantitation of Urinary Sediment Podocalyxin (u-sed-PCX) Predicts Urinary Podocyte Numbers

Session Information

Category: Pathology and Lab Medicine

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • Hara, Masanori, Niigata Wellness (Iwamuro Health Promotion Center), Niigata, Japan
  • Kurosawa, Hiroyuki, Denka Seiken Co., Ltd, Gosen, Japan
Background

Immunostaining of urine sediments shows a small number of podocytes and numerous cell debris resulting from the destruction of podocytes due to cell death, therefore, to know the exact number of urinary podocytes it needs to add a portion of cell debris to the number of podocytes evaluated as whole cells. In the present study we developed a procedure to count the exact podocyte numbers (podocytes + cell debris) in the sediments.

Methods

1) Urinary sediment PCX was quantified by ELISA (Diabetologia 55:2913, 2012) in normal control and various glomerular diseases.
2) The idea to obtain the exact number of urine podocytes is based on the calculation of urine sediment PCX (reflecting whole podocytes + cell debris from destructed podocytes) divided by PCX content belonging to single podocyte. We named this number as estimated urine podocyte number (eUPN).
3) To obtain the PCX content belonging to single podocyte we caluculated from 3 models; model 1 (assuming that it takes 150 years until complete podocyte loss from glomeruli in normal control), model 2 (evaluating podocyte loss during the interval in serial performed renal biopsies from our own patient with IgA nephropathy) and model 3 (evaluating podocyte loss from the published data in diabetic kidney disease (Diabetes 51;3083-3089, 2002). The mean value from 3 models was used in this study.
4) Several assumptive figures for normal control were used such as; urine volume:1000ml/day, Creatinine excretion:1 g/day, nephron number:1.5x106, podocyte number/glomerulus:500 cells.

Results

1) Single podocyte PCX content was calculated as 141.6, 153.2 and 100.0 pg/podocyte by model 1, 2 and 3, respectively. The mean value (131.6 pg/podocyte) was taken for determining eUPN in this study.
2) U-sed-PCX and (eUPN) in normal control, DKD, IgAGN, Nephrotic syndrome, Lupus nephritis, membranous nephropathy, ANCA related GN, and others were1.9 ng/mg creatinine (14.7 podocytes/mg creatinine), 3.6 (27.3), 2.0 (15.0), 11.5 (87.0), 7.1 (54.3), 5.2 (39.1), 1.7 (13.1), and 1.8 (13.3), respectively.
3) U-sed-PCX and (eUPN) in diabetic kidney diseases (normoalbuminuric, microalbuminuric and macroalbuminuric) was 1.6 (11.8), 3.7 (27.9) and 8.8 (66.7), respectively.

Conclusion

Quantitation of u-sed-PCX predicts more exact urinary podocyte number (eUPN), indicating this might be a better podometric biomarker in clinical nephrology.