LAUSR

The nephron number is thought to be associated with clinical outcomes of chronic kidney disease (CKD). If the nephron number can be estimated in a clinical setting, it could become a strong tool to predict the outcomes. This preliminary study estimated nephron number in CKD patients, and examined the relationship between the nephron number and patient characteristics. Data from a multicenter study of the National Hospital Organization of Japan were analyzed, including 565 CKD patients aged over 14 years who underwent a kidney biopsy. The nephron number was estimated by the glomerular density in biopsy specimens and the renal cortex volume. The renal cortex volume was calculated by the previously established equation using ultrasound measurement of the kidney. Linear regression models were used to investigate the associations of the nephron number separately with age, sex, and estimated glomerular filtration rate (eGFR). A total of 50% of the patients were women, and the mean (±SD) age of the patients was 51±19 years. The mean eGFR was 63±32 ml/min/1.73m2, and the mean estimated number of non-sclerotic nephrons was 660,000±320,000 per kidney. A larger number of estimated nephron number was associated with younger age, male sex, and higher eGFR. To the best of our knowledge, this was the first study to estimate the renal cortex volume and nephron number of CKD patients in the general clinical setting. The results from this study should provide powerful tools for nephrologists in routine clinical practice. Further investigations will be needed to verify the associations between the nephron number and clinical outcomes of CKD patients.