A new study published in Kidney Blood Pressure Research evaluated the influence of hemodialysis HD and hemodiafiltration HDF on plasma beta trace protein BTP and analyzed the inter and intra individual variability of plasma BTP over time in HD and peritoneal dialysis PD patients. Here the effect of a single session of low flux HD high flux HD and HDF on plasma BTP was studied in 12 prevalent HD patients. While in 13 HD patients and 10 peritoneal dialysis PD patients inter and intra individual variability over three months was studied. The findings showed no significant decrease in plasma BTP following a session of low flux HD. In contrast both high flux HD and HDF resulted in a significant decrease in plasma BTP immediately after dialysis. Moreover a significant reduction of the molecule persisted only in HDF and a significant decrease persisted immediately before the initiation of the next dialysis session. Furthermore in both HD and PD patients the reproducibility over time was remarkable. Additionally in a small cohort of PD patients fair agreement existed between mGFR average of renal urea and creatinine clearance from a 24 hours urine collection and the BTP based GFR glomerular filtration rate estimation. Thus it was concluded that BTP is a stable marker and a promising tool for residual renal function RRF estimations in PD and HD patients. It was stated that in patients receiving HDF plasma levels of BTP should be interpreted with caution.