How does chronic kidney disease progress?

Chronic kidney disease has five stages:

• Stage 1: Urine tests show clear signs of kidney damage. But healthy parts of the kidneys help them to keep working normally overall.
• Stage 2: Kidney function is slightly reduced, but there are no noticeable symptoms.
• Stage 3: Kidney function is moderately reduced. Even at this stage you usually won't notice any problems.
• Stage 4: Kidney function is significantly reduced. That means that the kidneys are barely able to do their job. This can cause symptoms such as itching, anemia, bone pain, fluid retention and physical weakness.
• Stage 5: Kidney failure: The kidneys are no longer able to clean the blood properly. Only a kidney transplant or dialysis can prevent the symptoms from getting worse and life-threatening complications from arising.

How chronic kidney disease develops will depend on what other health problems you may have. Heart disease, uncontrolled high blood pressure or diabetes can make kidney disease get worse faster. So it is important that your doctor keeps an eye both on how your kidneys are working and your overall health. Then the medications can be adjusted to meet your individual needs and your risk of kidney failure can be also be estimated better.

Various measurements that can be tested regularly at check-ups show how well your kidneys are working.

Each kidney has about one million tiny “filtering stations” in it called renal corpuscles. The glomerular filtration rate (GFR) shows how much blood is filtered per minute. This is between 85 and 135 milliliters per minute in people who are healthy. GFR gradually decreases in people with kidney disease.

It would be very difficult to measure the GFR directly. That's why it's usually estimated – for instance, using the level of creatinine in the blood. The formula for estimating the GFR also includes things like the person's age and sex.

Healthy kidneys stop certain components of the blood from getting into your urine and being flushed out of the body. Examples include blood proteins like albumin. If your kidneys have been damaged, then more blood proteins are released into the urine. The amount of protein in urine is taken as a sign of how bad the damage is.

A kidney transplant is often the best option for people who have kidney failure, but it isn't always possible to do immediately. A suitable donor organ needs to be found first. It can take several years to receive a donor kidney from a deceased person. It is often possible to get a living donor organ faster - for example from a close relative. Some people don't want to have a transplant though. Then it’s necessary to have dialysis, which you will also need while waiting for a donor organ.

Either peritoneal dialysis or hemodialysis can be used. But it can take some time to decide on one of these types of dialysis and to prepare the treatment. So the necessary preparations should be made as soon as it is clear that the kidneys will soon be failing. That is often the case if GFR drops below 30. Kidney failure occurs in most people who have a GFR below 10.