Kidneys

Overview

Your kidneys are two bean-shaped organs, each about the size of your fist. They sit near the middle of your back, one on each side, just below your ribs. Their main job is to clean your blood. Each day they filter about 150 litres of blood and take out waste, extra salt and extra water. That waste leaves your body as urine (pee). Your kidneys also help control your blood pressure, keep your bones strong, and help make red blood cells. When doctors talk about 'kidney disease', they mean the kidneys have been damaged and are not filtering as well as they should. This usually happens slowly over many years, and it can range from mild to serious.

Yes. Kidney problems are common. Around 1 in 10 adults worldwide has some form of kidney damage, and many of them do not know it. Most cases are mild and stay stable for years, especially when they are found early and looked after.

Anyone can be affected, but some people are at higher risk. This includes people with diabetes or high blood pressure, people over 60, people with a family history of kidney disease, people who have had kidney stones or repeated urine infections, and people who smoke or are very overweight. Kidney disease is also more common in people of South Asian, African or Caribbean background. Some children are born with kidneys that did not form or develop typically, and this is often picked up on a scan before birth or in early childhood.

Symptoms

Common symptoms

• Often no symptoms at all in the early stages — this is very common
• Feeling more tired than usual, or lacking energy
• Swelling in your ankles, feet, hands or around your eyes
• Peeing more often, especially at night
• Frothy or foamy urine
• Blood in your urine (it may look pink, red or cola-coloured)
• Dry, itchy skin
• Feeling short of breath after light activity
• Feeling sick, or not wanting to eat
• Muscle cramps, especially at night
• Finding it hard to think clearly or concentrate

Symptoms in children

• Poor feeding, vomiting or slow weight gain in babies
• Swelling around the eyes, especially in the morning
• Puffy ankles or a swollen tummy
• Growing more slowly than expected
• Peeing very often, or wetting the bed after being dry
• Repeated urine infections or fevers with no clear cause
• Pale skin or unusual tiredness
• Some children have no symptoms and are found through a routine scan or urine test

Symptoms in older adults

• Feeling unusually tired, weak or 'not yourself'
• Confusion or trouble concentrating, which can sometimes be the main sign
• Poor appetite and unplanned weight loss
• Swollen legs or ankles
• Muscle cramps and restless legs
• Passing much less urine than usual, or feeling very thirsty
• Dehydration, especially during hot weather or after illness
• Symptoms that are blamed on 'just getting older' — a simple blood test can check your kidneys

Causes

Main causes

• Diabetes (high blood sugar) — the most common cause of kidney damage
• High blood pressure, which damages the tiny filters over time
• Glomerulonephritis — inflammation of the kidney filters, caused by the immune system
• Polycystic kidney disease — an inherited condition where fluid-filled sacs grow in the kidneys
• Blockages in the urinary system, such as kidney stones or an enlarged prostate gland
• Repeated urine infections, especially in children or when a kidney is scarred
• Long-term use of some everyday painkillers, which can harm the kidneys if taken regularly for a long time
• Certain other medicines, such as some used after an organ transplant or for some immune conditions
• Sudden kidney injury (acute kidney injury) after severe illness, dehydration, infection or major surgery

Risk factors

• Having diabetes or high blood pressure
• Having heart disease or having had a stroke
• A family history of kidney disease
• Being over 60 years old
• Smoking
• Being overweight
• Having had kidney stones or repeated urine infections
• Being of South Asian, African or Caribbean background
• Taking some medicines long term — ask your pharmacist or doctor to check
• Long-term dehydration, or repeated bouts of severe illness

When to see a doctor

See a doctor urgently if:

• You can see blood in your urine
• You have a fever with pain in your back or side, or you feel shivery
• You are passing much less urine than usual
• Your legs, ankles or face have suddenly become swollen
• You are pregnant and have new swelling, headache or visual changes
• A child has swelling, blood in the urine, or is passing urine very often

Book a routine appointment if:

• You feel tired all the time and cannot explain why
• You have diabetes or high blood pressure and have not had a kidney check recently
• A close relative has kidney disease
• You keep getting urine infections
• You have itchy skin, muscle cramps or a poor appetite that will not settle
• You take regular painkillers and want to know if they are safe for your kidneys
• You are just worried and would like a check-up — this is a good enough reason on its own

Diagnosis

Kidney problems are usually found with two simple tests: a blood test and a urine test. Neither takes long. The blood test measures how well your kidneys are filtering, and the urine test looks for protein that should not be there. Your doctor will also check your blood pressure and ask about your health, your family history and any medicines you take. If the results are abnormal, you may have a scan of your kidneys, or be referred to a kidney specialist (a nephrologist — a doctor who specialises in kidneys).

Tests that may be done

• Blood test for creatinine, used to work out your 'eGFR' — an estimate of how well your kidneys filter
• Urine test for protein, called the albumin-to-creatinine ratio (ACR) — a very early warning sign
• Urine dipstick test, done in the GP surgery, which can show blood, protein or infection
• Blood pressure measurement
• Blood tests for salts such as sodium, potassium and calcium
• A full blood count to check for anaemia (low red blood cells)
• An ultrasound scan, which uses sound waves to take pictures of the kidneys
• A CT scan or MRI scan for stones, blockages or unusual shapes
• A kidney biopsy, where a tiny sample of tissue is taken with a needle and looked at under a microscope

What to expect at your appointment

Usually you will be asked for a blood and urine sample, and you will get the results within a few days. If your results are mildly abnormal, your GP will often repeat the test after a few weeks to see whether the change is permanent or just a one-off. Your results are usually put together with your age, sex and background to give a single number, your eGFR. It is easy to feel anxious, so it helps to ask: 'What does this number mean for me, and what happens next?' You can also ask for a printed copy of your results to keep.

Treatment

Treatment depends on what is causing the kidney problem and how much the kidneys have been affected. For most people, the aim is to protect the kidneys, slow any damage and keep you feeling well. There is no single cure for long-term kidney disease, but a lot can be done. Small, steady changes often make a big difference over the years.

Self-care at home

• Cut down on salt — most of it comes from ready meals, bread, cheese, sauces and processed meats rather than the salt cellar
• Keep well hydrated, unless your doctor has told you to limit fluids
• Stay active — regular walking, swimming or cycling helps blood pressure and heart health
• If you smoke, get support to stop. Your GP or pharmacist can help
• Keep alcohol within the general advice for everyone
• Lose a little weight if you need to — even small amounts help
• Check any painkillers or supplements with your pharmacist before taking them regularly
• Take any prescribed medicines as agreed, and ask if you are unsure why you take one
• Keep your blood pressure and blood sugar in the range your care team sets for you
• Go to your annual kidney check even when you feel well

Medical treatments

Doctors treat kidney problems by tackling the underlying cause and protecting the kidneys themselves. Common approaches include medicines to lower blood pressure, medicines that protect the kidneys in people with diabetes, and medicines that help remove extra fluid from the body. Other treatments can support problems that come with kidney disease, such as low red blood cells, weak bones or a build-up of acid in the blood. Some people with inflammation of the kidney filters are given medicines that calm the immune system. If the kidneys become seriously damaged, treatments to replace kidney function are used — either dialysis (a machine that cleans the blood, done at home or in hospital) or a kidney transplant. Your care team will explain each option in plain terms and help you decide what suits your life.

When is surgery considered?

Surgery is not needed for most kidney problems. It may be considered to remove a kidney stone that is blocking the flow of urine, to clear a blockage such as an enlarged prostate, to place a small tube (stent) to help urine drain, or to create a safe access point in the body for dialysis. A kidney transplant is a major operation that is an option for some people with advanced kidney disease. Your doctor will explain the benefits and risks in full before anything goes ahead.

Living with this condition

Most people with a kidney condition carry on with work, family life and hobbies much as before. The main difference is usually a yearly review, a few medicines, and paying a bit more attention to salt, fluids and blood pressure. It helps to keep a simple record of your readings and test results, and to bring a list of your medicines to every appointment. Ask for the name of the person to contact if you feel unwell between visits.

Lifestyle tips

• Build a routine around your medicines so you do not forget them
• Keep a home blood pressure monitor and log your readings if your care team advises it
• Plan meals ahead so salt and processed food are less likely to creep in
• Stay physically active most days, in a way you enjoy
• Get enough sleep, and rest when your body asks for it
• Tell any doctor, dentist or pharmacist that you have a kidney condition
• Ask before taking new over-the-counter medicines, herbal remedies or supplements
• Keep up with routine vaccinations as your care team advises
• Have a plan for hot weather and for days when you are ill, such as vomiting or diarrhoea — ask your team what to do about fluids and medicines

Diet and exercise

You do not usually need a strict diet, but a balanced, home-cooked way of eating helps. Aim for plenty of vegetables, fruit, beans, lentils, wholegrains and plain water. Cut back on salt by flavouring food with herbs, spices, lemon and pepper instead of stock cubes and sauces. Some people are asked to watch potassium or phosphate, which are found in foods such as bananas, nuts, dairy and cola — only limit these if your care team tells you to, because over-restricting can do harm. For exercise, aim for something that makes you slightly warm and a bit out of breath, for around 30 minutes on most days. Walking counts. If you are new to exercise or have heart problems too, start gently and ask your GP or a physiotherapist for advice.

Mental health and emotional wellbeing

It is normal to feel worried, low or overwhelmed when you are told something is wrong with your kidneys. Some people feel angry (why me?), and some feel a loss of control. These feelings usually soften as you learn more and see that there is a clear plan. Talking helps — with a friend, your GP, or a counsellor. If you are feeling low, hopeless or having thoughts of harming yourself, please reach out today. Contact your GP, your local mental health service, or a crisis line in your country straight away. If you feel you are in immediate danger, call your local emergency number.

Prevention

You cannot prevent every kidney problem — some are inherited or caused by conditions you cannot control. But many of the most common causes are very preventable or manageable. Keeping blood pressure and blood sugar in a healthy range, not smoking, staying active, eating less salt and keeping to a healthy weight all protect your kidneys. Get your kidneys checked if you have diabetes, high blood pressure or a family history, because finding a problem early is the biggest advantage you can give yourself. Also ask your pharmacist before using painkillers regularly or combining medicines.

Vaccines

People with kidney conditions are often advised to have routine vaccinations, such as flu and pneumonia vaccines, because infections can be harder on the body. Ask your GP or pharmacist which vaccinations are recommended for you and when to have them.

Screening programmes

There is no national screening programme for kidney disease for everyone. Instead, doctors test people who are at higher risk. If you have diabetes, high blood pressure, heart disease or a family history of kidney disease, ask your GP for a kidney blood and urine test — it is quick and usually done alongside your routine checks. A simple urine test in pregnancy and in children with repeated infections also helps catch problems early.

Complications

If left untreated

• Waste products building up in the blood, causing tiredness, nausea and confusion
• High blood pressure that is harder to control, which puts strain on the heart
• Anaemia — too few red blood cells, causing breathlessness and tiredness
• Weaker bones and a higher chance of fractures
• Fluid building up in the lungs, causing breathlessness
• Heart and blood vessel disease, which is the most common complication
• Nerve damage causing tingling in the hands and feet
• Advanced kidney failure, where dialysis or a transplant may be needed
• A higher chance of sudden kidney injury during another illness

Long-term outlook

The outlook is better than many people expect. Most kidney problems are found at a mild stage, and with steady blood pressure, good blood sugar control, a sensible diet and regular check-ups, many people stay stable for decades. Even with more advanced kidney disease, people live full lives — working, travelling and spending time with family. Dialysis and transplant are treatments that many people adapt to well. The most useful thing you can do is keep your appointments and ask questions when something is unclear. Your care team is on your side.

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