Why do kidneys fail?

Your kidneys are vital organs that keep your blood clean and chemically balanced. Healthy kidneys clean the blood by filtering out extra water and waste products. They also produce hormones that keep your bones strong and your blood healthy.

There are many different reasons for decreased kidney function. Two of the most common are diabetes and high blood pressure.

Kidney failure

If the kidneys are damaged, patients produce a lot less urine or no longer urinate at all, while waste products continue to be produced. These waste products build up in the bloodstream, as does the water content. This condition is called uraemia. Your hands or feet may swell and, you may become short of breath. Your blood pressure may rise and your body will not make enough red blood cells. You may develop fatigue, nausea, and loss of appetite. Untreated uraemia may lead to seizures or coma and will ultimately result in death.

When the kidneys function at 15 percent or less, this is called kidney failure. If this happens, treatment is needed to replace your failed kidneys. Your kidney function can only be replaced by dialysis or by transplantation.


There are two types of diabetes. Diabetes type 1 means that your body does not produce enough insulin to break down the sugar in your blood. Diabetes type 2 means that you are not making effective use of the insulin that you produce. If diabetes is not controlled properly, sugar will start to build up in your blood. When the amount of sugar becomes too high, it can cause damage that will reduce the ability of your kidneys to filter out waste products and fluids. Although treatment of diabetes has improved, many people with diabetes may still develop kidney damage within 20-30 years of diagnosis.

High blood pressure/Hypertension

High blood pressure occurs when the pressure of your blood against the walls of your blood vessels increases above the normal. High blood pressure will damage the small blood vessels in your kidneys and prevent the filtering process from working properly. The reasons for high blood pressure are to a large extent unknown. However, there often seems to be a connection with your general health, lifestyle and diet.

Kidney inflammation (glomerulonephritis)

Another common type of kidney disease is inflammation in the kidney’s filtering units. This may cause a decrease in the output of urine, the leakage of blood and protein into the urine, and swelling of hands and feet (oedema).

Other causes for kidney failure

Polycystic kidney disease is an inherited disease which can cause large cysts to form in the kidneys and lead to kidney failure.

Obstructions in the urinary outflow cause urine to flow back up to the kidneys, which may damage them. Obstructions can be caused by: narrowing of the urethra which often develops before birth, kidney stones, tumours or an enlarged prostate gland in men.

Repeated urinary infections may also be a reason for kidney failure.

Causes unknown

For about 20 % of dialysis patients, a cause for their kidney failure is never found. These patients often come for treatment for the first time when their kidney failure is far advanced and, it is difficult to establish the reason behind their disease at this stage.

Replacing your kidney function

For patients recently diagnosed with kidney failure, the prospect of dialysis can be a frightening. To offset the anxiety associated with dialysis treatment, it is important to prepare yourself for treatment, well in advance, to ensure you are physically, mentally and emotionally ready for this life-sustaining treatment.

Most likely, planning will have started much earlier to prepare you for this new stage of your life. Your medical team will discuss the options with you and help you make a decision that will suit your personal and medical needs. Often the preparations for dialysis and transplantation will start at the same time.

Related content

About our kidneys
The main tasks of your kidneys are to filter waste substances and balance the levels of salts and water in your body
Chronic kidney disease is a severe disorder that has become increasingly common worldwide
Treatment & dialysis
When severe loss of kidney function occurs, the kidneys function must be replaced