What do the kidneys do?
The kidneys have several functions including:
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Removal of waste products, toxins and poisons from the blood | The kidneys filter and clean the blood by putting toxins, waste products and poisons into the urine. |
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Maintaining the right amount of fluid in the body | If there is more fluid than is ideal, the kidneys make more urine. On the other hand, if you are dehydrated, the kidneys hold on to water. |
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Making hormones | The kidneys make hormones that
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What happens when the Kidneys go wrong?
It is common to have no symptoms at all of kidney disease until the kidney function is
significantly reduced. The problems that can then occur include:
- Itchiness, nausea and loss of appetite - due to waste products and toxins that build up in the blood
- Swelling in the feet and legs and shortness of breath - due to build of fluid in the feet, legs and lungs
- Anaemia and problems with bones and muscles – due to lack of hormones
- High blood pressure (hypertension) - due to a combination of problems with hormones and the balance of body fluid
A sudden and short-term problem with the kidneys is often called an “Acute Kidney Injury” (AKI). AKI usually settles with treatment, although sometimes the damage cannot be completely reversed.
A longer-term reduction in kidney function is known as Chronic Kidney Disease (CKD). This does not necessarily mean that kidney damage is severe. Many people with CKD have mild but long-term kidney disease.
Who is more likely to get kidney problems?
Although anyone can run into trouble with the kidneys, some specific conditions, situations and risk factors increase the chance of developing kidney problems. These include:
- Diabetes, especially if blood sugar control is not good
- High blood pressure, especially if not well controlled
- Cardiovascular disease (ischaemic heart disease, chronic heart failure, peripheral
vascular disease or cerebral vascular disease) - Having somebody in the family with kidney disease
- Being of Asian ethnicity
- Smoking
- Being overweight or obese
- Some medications (eg Ibuprofen) and illicit drug (eg cocaine, heroin)
How is kidney function assessed and monitored?
There are two ways of working out how well the kidneys are working:
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Urine tests – the kidneys make urine, so checking that the urine is normal is a very useful way to tell if there are problems with kidney function. Changes in the urine can be the very first sign that the kidneys are struggling. Urine samples can be tested for the presence of blood, protein and infection. Urine should not usually contain either blood or protein. The first line test for protein in the urine is called the “albumin to creatinine ratio” (ACR). If there is a problem with the way that the kidneys filter and clean the blood, then small amounts of protein leak into the urine and the ACR measurement is high. If the ACR is very high, then sometimes a second urine sample called a “protein to creatinine” (PCR) ratio is needed. |
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Blood tests – the usual blood test for kidney function is called “creatinine”. Creatinine is a chemical in the blood that comes from the energy producing processes in muscle. The kidneys usually get rid of creatinine in the urine. If the kidneys aren’t working properly, the creatinine level in the blood can increase. The laboratory will use the creatinine concentration to work out your estimated glomerular filtration rate (eGFR). The eGFR is a mathematical calculation of how well the kidneys are able to filter and clean the blood. A normal eGFR is more than 90 ml/min. |
Who should have their kidney function assessed regularly?
Blood tests for kidney function are often done if people are unwell or have symptoms that may be due to kidney problems.
People on long term medication that can affect kidney function should have regular blood tests to assess eGFR. This is usually done annually.
In addition, some people need routine blood and urine checks. ACR, creatinine and eGFR should be monitored at least once a year for people with any of the following:
- diabetes
- high blood pressure (hypertension)
- previous kidney problems
- cardiovascular disease (ischaemic heart disease, chronic heart failure, peripheral
vascular disease or cerebral vascular disease) - problems with the structure of the kidneys
- recurrent kidney stones
- enlarged prostate
- diseases involving multiple organs, for example, systemic lupus erythematosus
- gout
- kidney disease that runs in families
How can kidney disease be prevented and treated?
Prevention
A lot of kidney problems cannot be prevented, however, if you do have specific risk factors, there are things that you can do to reduce the risk:
- Healthy lifestyle – kidney disease is linked with diabetes, high blood pressure and high cholesterol. Eating a healthy and balanced diet, maintaining a healthy weight, moderating alcohol intake, not smoking and doing plenty of physical activity all significantly reduce blood pressure and cholesterol as well as helping to prevent or control diabetes.
- Diabetes – if you have diabetes, making sure you have good blood sugar levels significantly reduces the risk of developing kidney disease. It is very important to control blood sugar as soon as diabetes is diagnosed. Delays in getting blood sugars to target increases the risk of kidney disease as well as all the other long term complications of diabetes.
- Blood pressure – although it is a common risk factor, not everyone with high blood pressure develops CKD. Maintaining a healthy lifestyle reduces the risk of having high blood pressure in the first place and improves blood pressure control. There are also many good medications for blood pressure which can prevent the kidneys from being damaged
Treatment of established / chronic kidney disease (CKD)
Although there is no cure for established kidney disease, there are things that can be done to slow down any deterioration in kidney function. In addition, there are many treatments for the symptoms associated with kidney problems. The options available depend a bit on the stage of kidney disease and include:
- Lifestyle – staying healthy through regular exercise, eating a healthy diet, including reducing the salt that you eat, and controlling blood pressure can help kidney disease from getting worse. Some people with CKD need to be on a special diet to reduce the risk of complications.
- Medicines – Some medicines can help slow any reduction in kidney function. There is also medication available to control disease complications such as high blood pressure and high cholesterol as well as treatments to reduce the risk of CVD. Finally, there are some medications (such as over-the-counter Ibuprofen or similar) that should be avoided to protect kidney function. Your healthcare team will advise you on the best mix of medication for you.
- Dialysis – Removal of waste products and excess fluids from the blood. This is used for people with significant kidney disease (also known as CKD stages 4 – 5). There are two types of dialysis:
- Haemodialysis – this is when blood is diverted into an external machine to be filtered before returning to the body. Haemodialysis is usually done three times a week, either in a clinic or at home.
- Peritoneal dialysis – the abdomen (tummy), has a lining called the peritoneal membrane which can be used as a filter. A small soft tube, called a catheter, is put through the skin of the tummy in a minor operation. Special dialysis fluid can then be used to draw waste products and excess fluid out of the blood. This is done at home several times a day or overnight.
- Kidney transplant – The average kidney transplant lasts around 20 years, so many people will need more than one in their lifetime. Kidney transplants require a major surgical procedure and long-term medication to prevent rejection of the transplant.
What is the link between Cardiovascular disease and Kidney Disease?
Cardiovascular and kidney disease can be connected in two ways:
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Although heart disease is more common in people with kidney problems, there is a lot that can be done to reduce the risk:
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Healthy Eating
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Just making changes to what you eat can help reduce risk your risk of CVD. In addition, eating a healthy diet can help with weight management as well as bring down your blood fats and blood pressure. Some people with kidney disease need to be on special diets and it is often useful to see a dietician as it can be difficult to be sure what is best for you. |
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Lowering high blood fats
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Your healthcare professional will talk to you about your targets for blood fats. Eating a healthy diet, being a healthy weight and doing physical activity are critical to achieving good levels of cholesterol and triglycerides. Many people also need medication to reach their blood fat goals. |
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Losing weight
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Although not everyone with kidney disease at risk of CVD is overweight, achieving and maintaining a healthy weight is an extremely effective way of reducing CVD. In addition, if you are overweight, you can improve blood pressure, blood fats and diabetes control by losing weight. Your healthcare team will support you in your journey with weight management. |
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Increasing physical activity
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Physical activity is important for people with long-term kidney problems to improve muscle strength and bone health as well as reducing the risk of CVD. In addition, physical activity can help with weight management, control of blood pressure, blood fats and diabetes. Most importantly of all, increasing physical fitness improves mental health, making people feel better in themselves. If you have kidney disease, you may have to make changes to the way you do physical activity and your healthcare team will support you in this. |
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Lowering high blood pressure
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Your healthcare professional will talk to you about your targets for blood pressure. Eating a healthy diet and reducing salt intake can make a huge difference to blood pressure. Many people also need medication to control blood pressure. |
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Giving up smoking
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This is very hard but extremely important as smoking is a major risk factor for kidney disease. Many GP practices have programmes to support people to stop smoking |
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Medication
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Some of the medications used to protect kidneys also reduce the risk of CVD. Drugs called SGLT-2 inhibitors (eg Dapagliflozin and Empagliflozin), which were originally used to treat diabetes, are now being given to people without diabetes because they both help stop kidney function from worsening and reduce the risk of CVD. |
Kidney health resources
Kidney Care UK
- https://kidneycareuk.org/
National Kidney Federation
- https://www.kidney.org.uk/
Kidney Research UK
- https://www.kidneyresearchuk.org/
UK Kidney Association
- https://ukkidney.org/
NICE Guidelines - Chronic kidney disease: assessment and management
- https://www.nice.org.uk/guidance/ng203/resources/chronic-kidney-disease-assessment-and-management-pdf-66143713055173
