Only Sparse Data Are Available for Elderly Patients
In our opinion, the article contains a few imprecisions. The authors describe methods of determining the measured and estimated glomerular filtration rates (mGFR and eGFR). With regard to the measurement approach we miss a more detailed explanation of the different approaches, or, at least, a citation of a recent review (1). With regard to the eGFR, the authors did not mention the so called CKD-Epi equation, which was published in May 2009 (2). This formula is more precise than the MDRD equation, and many laboratories are now providing this test.
Further, we do not agree with the reference ranges for the GFR listed in table 2. Especially in estimating renal function in patients older than 60 years, the data are scarce, and not a single eGFR formula has been validated. The Cockcroft-Gault equation as well as the MDRD equation underestimate renal function in this age group; when the CKD-Epi formula was developed the number of older people was too low to reach a definite conclusion. Giving an “age specific” GFR in elderly people is therefore difficult if not downright impossible. In view of current demographic trends, this is an important topic. Renal function in patients of an advanced age is being investigated in the context of the Berlin initiative study, a population based age exploration of renal failure in patients aged 70 or older.
PD Dr. med. Elke Schäffner, MS
Prof. Dr. med. Ralf Schindler
Universitätsmedizin Charité, Campus Virchow
Medizinische Klinik mit Schwerpunkt Nephrologie und
Augustenburger Platz 1
13353 Berlin, Germany
|1.||Stevens LA, Levey AS: Measured GFR as a confirmatory test for estimated GFR. J Am Soc Nephrol 2009; 20: 2305–13. MEDLINE|
|2.||Levey AS, Stevens LA, Schmid CH, et al.: A new equation to estimate glomerular filtration rate. Ann Intern Med 2009; 150: 604–12. MEDLINE|
|3.||Thomas C, Thomas L: Renal failure-measuring the glomerular |
filtration rate [Niereninsuffizienz – Bestimmung der glomerulären Funktion]. Dtsch Arztebl Int 2009; 106(51–52): 849–54.