Kidney disease in 3 minutes

What do the kidneys do?

They filter the blood to remove waste products, and to get rid of excess water and other things that you eat and drink.  Healthy kidneys filter well over 100mls of blood every minute.  That’s about 150 litres, or 33 gallons (40 US gallons) every day.  This is known as the GFR, short for Glomerular Filtration Rate.  Commonly we use a simple blood test to get an estimate of GFR, as is it tricky to measure GFR accurately.

eGFR is an estimate of kidney filtration

eGFR is an estimate of how well your kidneys are filtering.  It is calculated from the result of a blood test (creatinine) along with your age and sex.  As normal eGFR is round about 100, the eGFR gives you an approximate ‘percentage function’.  So  if your eGFR is 50, your kidneys are probably filtering at about 50% of normal.   It’s very approximate though, and there are times when it can’t be very reliable at all. It is not accurate at near-normal levels, so many labs report eGFR over 60 as just “>60” (more than 60).

What are the signs my kidneys aren’t working properly?

Most people with kidney trouble don’t have any symptoms at all.  Most of the diseases that cause pain (urine infections and kidney stones are examples) only rarely cause kidney failure.  Kidney failure only starts to cause much trouble when you’re down to 30% kidney function or less.  Even then the symptoms aren’t very obviously coming from the kidney.  More often high blood pressure or abnormal urine tests or something else leads to a blood test being done, and that shows it up.

Some of the signs of kidney trouble that you read about are very late signs, and not very helpful for picking up early kidney disease.

What is CKD?

CKD means Chronic Kidney Damage.  It means your kidneys aren’t 100% because

  • They are filtering less than they should.  Filtering less than about 60% of normal is called stage 3 CKD, and less than 15% is stage 5 or;
  • They leak blood or protein into the urine.  If filtration is good, this would be stage 1 or 2.

Chronic renal failure (CRF) is the old term for CKD and it sometimes still used to mean more advanced kidney failure.

Should I be tested for CKD?

  • You should be tested if you have
  • High blood pressure (maybe once a year)
  • Diabetes (once a year)
  • Another disease known to affect the kidney
  • And maybe if there is someone in your family who has developed severe kidney failure (perhaps every 5 years).

I’ve got something wrong with my kidneys – are they going to fail?

Most people with CKD have steady kidney function that doesn’t change much with time.  Warning signs that make eventual kidney failure more likely are:

  • If you are young
  • If you have blood in your urine (but there are other causes of this)
  • If you have a lot of protein in your urine
  • If you have worse kidney function
  • If your kidney function is getting worse

So any of these are signs that things need to be looked at more closely.

What should I do if I have stable CKD?

Stable CKD means that your kidney tests aren’t changing much.  Most people in this position have a very low risk of getting severe kidney disease, but their risk of heart disease and other health problems is increased.  So to look after yourself:

  • Lead a healthy life and eat a healthy diet
  • Look after your blood pressure
  • Look after your cholesterol and general health
  • Take regular exercise
  • Get checked occasionally to make sure your kidney function remains steady
  • Don’t fret about it, lead a full life

What if my kidney function is getting worse?

If it is definitely getting worse you may need to be seen by a kidney specialist to see what can be done to stop it, or make plans if it can’t be stopped.  They will look for

  • Diseases that can be treated
  • High blood pressure that can be improved
  • Other ways to protect you and your kidney function against further damage

and if necessary they will talk to you about what should be done if your kidneys carry on getting worse. More about CKD (patient info); and more about CKD stages 4-5 (staff info)

What about dialysis and transplantation?

Dialysis and transplantation are a modern miracle for people with ‘end stage’ kidney disease whose health is otherwise good.  They are no picnic though. Prevention is much better. More about dialysis and transplantation.

3 minutes wasn’t enough?

Most pages here at are aimed at staff rather than patients.  You may find good for further info, in particular

  • Edren Info has a page each on many kidney diseases, and more info about normal kidneys and kidney tests

Here are some other places you can go for info: