Bhandari suggests an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 may be normal in patients older than 70,1. The study he cites as evidence showed a decline in creatinine clearance at 0.75 ml/min/year reaching a mean of 107 (SD 22) ml/min in the eighth decade of life.2 His comment, that an 80 year old may be normally expected to have an eGFR of 45-50 ml/min/1.73 m2, is at odds with the evidence. Even allowing for the fact that creatinine clearance overestimates GFR, stage 3 chronic kidney disease is abnormal in elderly people. Importantly, stage 3 chronic kidney disease is associated with increased cardiovascular risk independent of age.3
Bhandari also states that eGFR is not validated in subjects with stage 3 chronic kidney disease and a “normal” serum creatinine.1 4 The study he cites did not calibrate serum creatinine to the modification of diet in renal disease laboratory, which may substantially increase the inaccuracy of eGFR, particularly in patients with low serum creatinine.5 Clinicians should be reassured that most UK laboratories reporting eGFR do calibrate their creatinine assays to an international reference standard.
Patients with chronic kidney disease should not be ignored simply because they are older than 70.
Competing interests: MSM has received lecture and consultancy fees and support to attend academic conferences from companies which manufacture drugs relevant to chronic kidney disease.
References
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