CHRONIC KIDNEY DISEASE

Chronic kidney disease (CKD) is a long-term condition where the kidneys do not work effectively.

CKD does not usually cause symptoms until it reaches an advanced stage. It is usually detected at earlier stages by blood and urine tests. Main symptoms of advanced kidney disease include:

  • tiredness
  • swollen ankles, feet or hands (due to water retention)
  • shortness of breath
  • nausea
  • blood in the urine

Chronic kidney disease is most frequently diagnosed through blood and urine tests.

If you are at a high risk of developing CKD, you may be screened annually. Screening may be recommended if you have:

  • high blood pressure (hypertension)
  • diabetes
  • a family history of CKD

Symptoms of chronic kidney disease

Most people with CKD have no symptoms because the body can tolerate even a large reduction in kidney function. 

In other words, we are born with a lot more kidney function than is necessary for survival. Kidney function is often sufficient if only one kidney is working. That is why people can give a kidney to someone needing a kidney transplant.

A change in kidney function is usually discovered through a routine blood or urine test. If you are diagnosed with kidney disease, your kidney function will be monitored with regular blood and urine tests, and treatment aims to keep any symptoms to a minimum.

If the kidneys continue to lose function and there is progression towards kidney failure (established renal failure or ERF), this will usually be tracked by blood tests and monitoring. If kidney failure does occur, the symptoms may include:

  • weight loss and poor appetite
  • swollen ankles, feet or hands (due to water retention)
  • shortness of breath
  • blood or protein in your urine (protein in your urine is not something you will notice as it can only be detected during a urine test)
  • an increased need to urinate, particularly at night
  • insomnia
  • itchy skin
  • muscle cramps
  • high blood pressure (hypertension)
  • nausea
  • erectile dysfunction in men (an inability to get or maintain an erection)

These are general symptoms and can be caused by many less serious conditions. Many of the symptoms above can be avoided if treatment begins at an early stage, before any symptoms appear.

Causes of chronic kidney disease

Kidney disease is most often caused by other conditions that put a strain on the kidneys.

High blood pressure (hypertension) and diabetes are the most common causes of kidney disease. The evidence indicates that high blood pressure causes just over a quarter of all cases of kidney failure. Diabetes has been established as the cause of around a quarter of all cases.

High blood pressure

Blood pressure is a measure of the pressure your heart generates in your arteries with each pulse. Too much pressure can damage your body’s organs, leading to heart disease, stroke and worsening of kidney function.

The cause of around 90% of cases of high blood pressure is unknown, although there appears to be a link between the condition and a person’s general health, diet, and lifestyle.

Known risk factors for high blood pressure include:

  • age (the risk of developing high blood pressure increases as you get older)
  • family history of high blood pressure (the condition seems to run in families)
  • being of African-Caribbean or south Asian origin
  • obesity
  • lack of exercise
  • smoking
  • excessive alcohol consumption
  • high amount of salt in your diet
  • high-fat diet
  • stress

Hypertension causes damage by putting strain on the small blood vessels in the kidneys. This prevents the filtering process from working properly.

Diabetes

Diabetes is a condition in which the body produces no – or too little – insulin (type 1 diabetes) or has become unable to make effective use of insulin (type 2 diabetes).

Insulin is needed to regulate levels of glucose (sugar) in your blood, preventing the levels going too high after a meal and too low between meals.

If diabetes is poorly controlled, too much glucose can build up in your blood. The glucose can damage the tiny filters in the kidneys, which affects the ability of your kidneys to filter out waste products and fluids.

It is estimated that 20-40% of people with type 1 diabetes will develop kidney disease before they reach 50 years of age. Around 30% of people with type 2 diabetes also show signs of developing kidney damage.

The first sign of diabetic kidney disease is the appearance of low levels of protein in the urine. Therefore, your GP will ask for an annual urine test so any kidney disease can be detected as early as possible.

All people with diabetes should have a kidney check every year. Early detection of kidney dysfunction in diabetes is important because it identifies people at risk or complications, such as eye problems and impotence.

Other causes

There are many other conditions that less commonly cause CKD, including:

  • glomerulonephritis (inflammation of the kidney)
  • pyelonephritis (infection in the kidney)
  • polycystic kidney disease (an inherited condition where both kidneys are larger than normal due to the gradual growth of masses of cysts)
  • failure of normal kidney development in an unborn baby while developing in the womb
  • systemic lupus erythematosus (a condition of the immune system where the body attacks the kidney as if it were foreign tissue)
  • long-term, regular use of medicines, such as lithium and non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin and ibuprofen
  • blockages, for example due to kidney stones or prostate disease

Diagnosing chronic kidney disease

Chronic kidney disease (CKD) is most frequently diagnosed through blood and urine tests.

Screening

If you are in a high-risk group for developing CKD, it is important to be regularly screened for the condition. People who are not in a high-risk group are not normally screened for CKD.

Annual screening is recommended for the following groups:

  • people with high blood pressure (hypertension)
  • people with diabetes
  • people with acute kidney injury caused by medications such as lithium or NSAIDs such as ibuprofen, kidney stones or an enlarged prostate
  • people with cardiovascular disease (conditions that affect the heart, arteries and veins, such as coronary heart disease or heart failure)
  • people with a family history of stage five CKD (see below for more information about staging) or an inherited kidney disease
  • people with diseases that affect several parts of the body and may affect the kidneys, such as systemic lupus erythematosus
  • people with blood in the urine (haematuria) or protein in the urine (proteinuria) where there is no known cause

Your GP can advise you about whether or not you should be screened for CKD.

Most often, the diagnosis of kidney disease is made because a routine blood or urine test indicates the kidneys may not be functioning normally. If this happens, the test is usually repeated to confirm the diagnosis.

Glomerular filtration rate (GFR)

An effective way of assessing how well your kidneys are working is to calculate your glomerular filtration rate (GFR). GFR is a measurement of how many millilitres (ml) of waste fluid your kidneys can filter from the blood in a minute (measured in ml/min). A healthy pair of kidneys should be able to filter more than 90ml/min.

It is difficult to measure the GFR directly, so it is estimated using a formula. The result is called the estimated GFR or eGFR. Calculating your eGFR involves taking a blood sample and measuring the levels of a waste product called creatinine and taking into account your age, gender and ethnic group. The result is similar to the percentage of normal kidney function. For example, an eGFR of 50ml/min equates to 50% kidney function.

The following tests are used to detect proteinuria (protein in the urine)

  • urine tests – used to see whether there is blood or protein in your urine
  • albumin and creatinine testing – this is another urine test which compares the amounts of albumin (a protein) and creatinine in your urine. The ratio of the two (the albumin:creatinine ratio or ACR) can be used with eGFR to give doctors a more accurate idea of how the kidneys are functioning

Staging

A six-stage system, based on eGFR levels, is used to describe the progression of CKD. The higher the stage, the more severe the CKD. The six stages are described below.

  • Stage one (sometimes called G1): the eGFR is normal (above 90 or more), but other testing shows evidence of kidney damage.
  • Stage two (G2): the eGFR has decreased slightly (60–89), but is still considered to be in the normal range for a young adult.

If you have stage one or two CKD, it is recommended you have annual eGFR tests so the progression of the condition can be carefully monitored.

  • Stage three is divided into two – stage 3a (G3a) and 3b (G3b).
    In stage 3a, the eGFR has decreased mildly (45–59) and this is termed a mild to moderate decrease in kidney function and should be checked annually. In stage 3b (G3b) it has decreased moderately (30–44) and is termed a moderate to severe reduction in kidney function and should be checked every six months.
  • Stage four (G4): the eGFR has reduced severely (15-29). By this time, it is possible you will be experiencing symptoms of CKD. Further testing should be carried out every six months.
  • Stage five (G5): the kidneys have lost almost all of their function (an eGFR of below 15), which is known as established renal failure. Further testing should be carried out every three months.

However, over time, GFR can fluctuate, so one abnormal test result does not automatically mean you have CKD. A diagnosis of CKD is usually only confirmed if repeated eGFR tests show your eGFR is consistently lower than normal over three months.

Other tests

A number of other tests are also used to assess the levels of damage to your kidneys. These are outlined below:

  • kidney scans, such as an ultrasound scan, a magnetic resonance imaging (MRI) scan or a computerised tomography (CT) scan – used to find out whether there are any unusual blockages in your urine flow. In cases of advanced kidney disease, the kidneys are shrunken and have an uneven shape
  • kidney biopsy – a small sample of kidney tissue is taken so that the cells can be examined under a microscope for damage

Preventing chronic kidney disease

In most cases, chronic kidney disease (CKD) cannot be completely prevented, although you can take steps to reduce the chances of the condition developing.

Managing your condition

If you have a chronic (long-term) condition, such as diabetes, that could potentially cause chronic kidney disease, it is important it is carefully managed.

Follow the advice of your GP and keep all appointments relating to your condition. People with diabetes are advised to have their kidney function tested every year.

Smoking

Smoking increases your risk of cardiovascular disease, including heart attacks or strokes, and it can increase the likelihood that any existing kidney problems will get worse.

If you stop smoking, you will improve your general health and reduce your risk of developing other serious conditions, such as lung cancer and heart disease.

The NHS smoking helpline can offer you advice and encouragement to help you quit smoking. Call 0300 123 1044 or visit the

Diet

A healthy diet is important for preventing chronic kidney disease. It will lower the amount of cholesterol in your blood and keep your blood pressure at a healthy level. Eat a balanced diet that includes plenty of fresh fruit and vegetables (5 A DAY) and whole grains.

Limit the amount of salt in your diet to no more than 6g (0.2oz) a day. Too much salt will increase your blood pressure. One teaspoonful of salt is equal to about 6g.

Avoid eating foods high in saturated fat because this will increase your cholesterol level.

Foods high in saturated fat include:

  • meat pies
  • sausages and fatty cuts of meat
  • butter
  • ghee (a type of butter often used in Indian cooking)
  • lard
  • cream
  • hard cheese
  • cakes and biscuits
  • foods that contain coconut oil or palm oil

Eating some foods that are high in unsaturated fat can help decrease your cholesterol level. Foods high in unsaturated fat include:

  • oily fish
  • avocados
  • nuts and seeds
  • sunflower oil
  • rapeseed oil
  • olive oil

Alcohol

Drinking excessive amounts of alcohol will cause your blood pressure to rise, as well as raising cholesterol levels in your blood. Therefore, sticking to the recommended alcohol consumption limits is the best way to reduce your risk of developing high blood pressure (hypertension) and CKD.

The recommended limits for alcohol are:

  • 3-4 units of alcohol a day for men
  • 2-3 units of alcohol a day for women

A unit of alcohol is equal to about half a pint of normal strength lager, a small glass of wine or a pub measure (25ml) of spirits.

Exercise

Regular exercise should help lower your blood pressure and reduce your risk of developing CKD.

At least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity (such as cycling or fast walking) every week, is recommended.

Painkillers

Kidney disease can be caused by the improper use (such as taking too many) of non-steroidal anti-inflammatories, such as aspirin and ibuprofen.

If you need to take painkillers, make sure you follow the instructions. This can help to avoid kidney damage.

Living with chronic kidney disease

A diagnosis of kidney disease can be worrying for you and your family, but it does not have to take over your life.

Although it is not possible to repair the damage that has already happened to your kidneys, it does not mean your kidney disease will definitely get worse. Less than 1% of people with stage three kidney disease develop kidney failure.

By leading a healthy lifestyle and following your doctor’s advice on treatment for high blood pressure and other conditions, it is possible to live without symptoms or further deterioration of your kidney function. At all stages of kidney disease, you can help reduce the chances of your kidneys getting worse and your risk of cardiovascular disease by living a healthier lifestyle.

Looking after your kidneys

The following steps can help keep your kidneys as healthy as possible:

  • do not smoke
  • maintain a healthy blood pressure (neither too high nor too low). You can do this by eating a varied diet (particularly avoiding added salt), living an active lifestyle (for example, doing gentle exercise and avoiding stress) and taking medication prescribed by your GP
  • reduce the amount of cholesterol in your diet. Cholesterol increases blood pressure and can impair kidney function
  • people with diabetes should make sure their blood sugar levels are kept under control

Self care

Self care is an integral part of daily life. It means you take responsibility for your own health and wellbeing, with support from the people involved in your care. Self care includes the things you do each day to stay fit, maintain good physical and mental health, prevent illness or accidents, and effectively deal with minor ailments and long-term conditions. People living with long-term conditions can benefit enormously if they receive support for self care. They can live longer, have less pain, anxiety, depression and fatigue, have a better quality of life, and be more active and independent.

Regular reviews

Because kidney disease is a long-term condition, you will be in regular contact with your healthcare team. A good relationship with your team means you can easily discuss your symptoms or concerns. The more the team knows, the more they can help you.

Keeping well

Everyone with a long-term condition such as kidney disease is encouraged to get a flu jab each autumn to protect against flu (influenza). They are also recommended to get an anti-pneumoccocal vaccination. This is a one-off injection that protects against a specific serious chest infection called pneumococcal pneumonia.

Healthy eating and exercise

Regular exercise and a healthy diet are recommended for everyone, not just people with kidney disease. They can help prevent many conditions, including heart disease and some forms of cancer. Exercising regularly can help relieve stress and reduce fatigue. Try to eat a balanced diet, containing all the food groups, to give your body the nutrition it needs. You will be advised by a dietitian if you need to follow a special diet. The advice you are given will depend on how well your kidneys are working, your blood test results and your own preferences about what you normally eat and drink.

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