Living Donor Research Living Donor Risks Living Kidney Donor

Measure Kidney Function Don’t Estimate It


Because direct measurement of GFR is cumbersome, it is often estimated using serum creatinine clearance. Problem is, most folks must lose more than 50% of their kidney function before the SCr measures above normal. The goal, of course, of eGFR is to produce results as close to mGFR as possible.


So – the authors compared estimated GFR with measured GFR in 508 consecutive living kidney donors.

“The level of agreement between mGFR [measured GFR] and all three eGFR [estimated GFR] values was poor…We conclude that reliance on creatinine-based eGFR values is unsatisfactory for the evaluation of potential living kidney donors.”


According to MedLine from the National Institute of Health, “measuring” GFR involves a blood test. Over here it talks about a catheter to ensure collection of all urine. OPTN’s policy on the medical evaluation of living kidney donor requires “Measurement of glomerular filtration rate by isotopic methods or a creatinine clearance calculated from a 24-hour urine collection”. To me, that sounds more like eGFR than mGFR (Neither of those methods involve blood). Disconcerting if true.


Admittedly, much of this can be confusing to a non-medical person (myself included). If you’re interested in reading further about ways to measure GFR, this might be a place to start:


Bhuvanakrishna, T., Blake, G., Hilton, R., Burnapp, L., Sibley-Allen, C., & Goldsmith, D. (2014). Comparison of estimated GFR and measured GFR in prospective living kidney donors International Urology and Nephrology DOI: 10.1007/s11255-014-0859-y

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