Can Total Nephron Number Predict Progressive CKD after Radical Nephrectomy?

Abstract

The histologic assessment of the nontumoral kidney parenchyma is recommended in kidney cancer management. This analysis allows an estimation of CKD risk in patients with favorable cancer-related prognosis and whose survival is correlated with progression toward ESKD.1 Denic et al.2 identify several predictive features of CKD progression by analyzing large wedges of nontumoral kidney parenchyma among patients with kidney cancer. Other than larger glomerular size and nephrosclerosis, the authors focused on the larger cortex per glomerulus as an independent predictor of progressive CKD. This observation emphasizes the clinical relevance of glomerular density as a witness of the total nephron mass. However, the significant inter-individual variability in kidney size requires to relate the glomerular density to the cortical volume, resulting in an estimation of the total nephron number, which in our opinion is a more accurate marker of kidney health than the glomerular density alone. The initial assessment of patients with kidney cancer generally includes a pre-treatment abdominal computed tomography, which allows us to estimate the total cortical volume of the nontumoral kidney. In patients without underlying kidney disease, the cortical volume of the healthy kidney combined with the glomerular density estimation assessed in the nontumoral parenchyma provides an accurate evaluation of the total nephron number of the concerned kidney.3 This method is on the basis of the hypothesis of a homogeneous repartition of the glomeruli between two similar-sized kidneys (not taking the tumor into account). The total nephron number is probably a crucial determinant of CKD progression after the removal of half of the nephron mass, reflecting the adaptation capacities of the remaining kidney due to the increased filtered load per glomerulus.4 Considering its relevance, the total nephron number should be more commonly measured to predict progressive CKD. Disclosures J. Rebibou reports other interests/relationships with French Society of Nephrology Dialysis and Transplantation and ISN. All remaining authors have nothing to disclose. Funding None.