CKD (1-3)

Most early kidney disease is asymptomatic – people are unaware of it. It is usefully divided into stages.  Symptoms are usually unimpressive before late stage 4.

The 5 K/DOQI CKD stages (Kidney Diseases Outcome Quality Initiative – KDOQI (NKF, USA)

Management, comments
Normal kidney function but urine or other abnormalities point to kidney disease Stages 1-3 (5-10% of the population?)
Need assessment, long term monitoring, control of blood pressure and CV risk factors
Mildly reduced kidney function; but must also have urine or other abnormalities (e.g. anatomical, genetic) to be classified as CKD
Moderately reduced kidney function; may be subdivided into 3a, 3b according to GFR over or under 45; and proteinuric or not. Few or no symptoms still
Severely reduced kidney function 0.2% of the population. Planning for endstage renal failure if progressive.  Symptoms at lower GFRs.
14 or less
Very severe kidney failure. Sometimes used to imply endstage, ESRF or ESRD, but average GFR for starting dialysis is below 10. 0.2%

Stage 3 CKD is common – estimates of incidence vary, but it may be round about 5% of the population, mostly elderly.  Stages 1 and 2 could add nearly as many again, but this data is less reliably collected.  Stage 4 is much less common, and stage 5 is uncommon.

The widespread adoption of eGFR reporting and in the UK, the QOF (quality outcomes framework) in general practice have led to many more people becoming aware that they have proteinuria or reduced kidney function.  Most of these are elderly – the incidence of stage 3+ CKD rises very steeply over the age of 70 – and most never develop ESRF.  The most important risk factors for developing ESRF are:

  • Deteriorating function – unsurprisingly, if GFR falls with time, ESRF is more likely
  • Severe of CKD – worse kidney function is more likely to deteriorate further
  • Proteinuria is a strong risk factor, risk increasing with the severity of proteinuria.
  • Haematuria can be an indicator of kidney inflammation
  • High blood pressure – and blood pressure reduction reduces risk
  • Young age – younger patients with CKD are more likely to reach ESRD

Most patients do not have these, and for them, increased cardiovascular risk is of greater immediate concern.  CKD is associated with substantially increased risk of heart attacks and all kinds of cardiovascular disease, and if a patient with CKD has a cardiovascular event, or an operation, the risk of doing badly is substantially increased.  Any patient with CKD should therefore have management of all  risk factors attended to; this may involve blood pressure control, cholesterol/lipids, lifestyle alterations (smoking, weight, exercise), etc.

Assessment and referral guidelines use these factors to identify which patients should be referred for specialist assessment and how their risk might be assessed.

Preventing progression – see preventing progression in the next section on CKD 4-5 (CRF).

Early CKD is an invented disease?

Some have accused nephrologists and the renal community of scare mongering and inventing ‘new diseases for healthy people’ in publicity about early CKD. Average GFR falls with age, and the widespread use of equations to report eGFR automatically has led to many older people, especially women, being labelled CKD3.  Are they abnormal?

Probably most of them are, though the female preponderance has not been adequately explained.  Imagine X-raying the hip of an 85 year old.  It is quite likely to show some osteoarthritis.  Is this normal, just because the hip is 85?  No, it is abnormal, but if the patient is 85 it maybe isn’t so surprising.

Seymour Jones and the Temple of CKD (YouTube) … misleading but entertaining.  This video emphasises some of these issues – but the ‘early warning’ symptoms and signs it mentions are in fact late signs of CKD – late stage 4 and stage 5. Useful for students, but not useful for early detection by patients. Stages 1-3 are usually asymptomatic and often CKD 4 is too!

There are more resources on the Internet but beware quality!  Some resources, even paid resources, are quite poor.  We can vouch for the UK CKD eGuide, you’ll learn a lot if you work through that.  Kidney Research UK’s YouTube channel has some good videos on CKD.