NEXT ONLINE CONSULTATION: Kidney conditions. Send your questions on this topic for Dr Stuttaford's answers online on Wednesday, August 1. How to send a question; recent topics

A 76-year-old reader had a routine blood test that found that his estimated glomerular filtration rate, eGFR, was on the verge of stage 2 and stage 3 chronic kidney failure. It sounded alarming, but his doctor was unconcerned and merely said that he would check the result regularly. Was this response adequate?

Renal failure was formerly assessed by GPs measuring levels of a patient’s serum creatinine and blood urea. Creatinine is produced by muscles and filtered by kidneys. Its level, and that of blood urea, give an indication of how well the kidneys are working. The eGFR test is based on blood creatinine levels, but it also takes into account age, sex and race.

The test gives a better indication of a patient’s kidney performance. Most doctors agree that it raises alarm signals earlier than the older tests but suggest that the result may cause unnecessary alarm. One person in ten, using the standard eGFR, has some chronic kidney disease (CKD). One person in two over 75 years of age has an eGFR that suggests CKD, if they had other biochemical evidence of renal failure.

A patient with an eGFR of more than 90 and other evidence of kidney damage has stage 1 CKD. Patients with between 60 and 90, and other evidence of renal disease, are stage 2 CKD. Between 30 and 59, even without evidence of kidney disease, signifies stage 3 CKD. An eGFR of between 15 and 29 means a severe reduction in kidney function – stage 4 CKD. A score of Iess than 15 means the patient needs dialysis or a kidney transplant – stage 5 CKD.

The reader’s score of 64 denotes only stage 2 kidney disease if he has other biochemical evidence of it. In the absence of this, the doctor was wisely recommending only that the test is repeated annually.

Why does the eGFR matter? Early diagnosis of moderate reduction in kidney function is important. It is vital to slow the progress of renal failure – 3,400 people die each year of end-stage CKD, most of whom would have benefited from a transplant if one was available.

The recent introduction of Mircera, which treats the anaemia of kidney disease by stimulating the bone marrow to produce more red blood cells, reduces the problems of the complications of CKD.

Ask Dr Stuttaford Send your questions on other topics to drstuttaford@thetimes.co.uk
or to times2, The Times, 1 Pennington Street, London E98 1TT.

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