Blog entry by Meguid El Nahas
When will nephrologists learn that estimated GFR (eGFR; estimated by the MDRD equation or any other equation) does NOT equate to measured GFR (mGFR) or even calculated GFR (cGFR = CrCl + Urea Cl : 2)?!
This month in NDT, an article by Evans et al from Middlesborough UK reports that Irbesartan delays the progression of nephropathy as measured by eGFR: A post hoc analysis of the IDNT trial.
Wow....some findings...so the data reported by IDNT in the NEJM in September 2001 relating to changes in serum creatinine levels...took 10 years to convert to eGFR.... and show...surprise, surprise...that Irbesartan slows the progression of T2Diabetic Nephropathy!!!!!
When will nephrologists learn that changes in serum creatinine and their beloved eGFR does NOT mean changes in TRUE GFR!?
In fact, the observed changes may well be due to changes in tubular sercretion of creatinine, known to be affected by RAAS inhibition and improved peri-tubular capillary circulation and proximal tubular Creatinine transport, known to be attenuated in DM.
When will nephrologists learn that changes in albuminuria are not solely the result of changes in glomerular loss of albumin?
In the report under discussion, Irbesartan decreased albuminuria, an effect somehow linked to improved outcome?!
Nephrologists need to remember that RAS inhibition also improves peritubular circulation and thus proximal tubukle reabsorption of albumin.
When will nephrologists learn:
That in RCT the progression of CKD and GFR have to be MEASURED not estimated by inappropriate derivative equations....?!