Acute Kidney Injury

Overview

Acute kidney injury (often called AKI) is a sudden drop in your kidneys' ability to filter waste and extra fluid from your blood. It develops over hours or days. With prompt treatment, many people regain normal kidney function.

Yes, it's quite common. In the UK, AKI is found in about 1 in 5 people who are admitted to hospital as an emergency. It can also develop during a hospital stay.

Anyone can get AKI, but it's more likely if you are over 65, have chronic kidney disease, diabetes, heart failure, or liver disease. It also affects people who are very dehydrated, are severely infected (sepsis), or take certain medications that can harm the kidneys.

Symptoms

Common symptoms

• Little or no urine (fewer wet visits to the toilet)
• Swelling in your legs, ankles, or face
• Feeling unusually tired or weak
• Nausea, vomiting, or loss of appetite
• Feeling confused or 'not with it'
• Shortness of breath

Symptoms in children

• Fewer wet nappies or needing less toilet trips than usual
• Vomiting or refusing to feed
• Being very sleepy or hard to wake
• Swelling around the eyes or legs
• Pale or flushed appearance

Symptoms in older adults

• Confusion or drowsiness that is new
• Not making much urine
• Swelling in legs or ankles
• Feeling weak and dizzy
• Nausea and loss of appetite

Causes

Main causes

• Your kidneys are not getting enough blood (for example, from severe dehydration, heavy bleeding, or low blood pressure)
• Direct damage to the kidneys (for example, from a serious infection, certain medicines, or other illness)
• A blockage that stops urine leaving the body (for example, an enlarged prostate, kidney stones, or a stretched bladder)

Risk factors

• Being over 65
• Already having kidney disease or diabetes
• Heart failure or high blood pressure
• Being in hospital for a serious illness or major surgery
• Using medicines that can affect the kidneys (ask your doctor or pharmacist)
• Dehydration from vomiting, diarrhoea, or not drinking enough

When to see a doctor

See a doctor urgently if:

• Go to an urgent care clinic or call your local health service if you notice a big drop in how much urine you pass, swelling in your legs or face, or you feel unusually tired and confused.

Book a routine appointment if:

• If you have a higher risk of kidney problems, talk to your doctor at your next check-up about how to protect your kidneys.

Diagnosis

Your doctor will ask about your symptoms, recent illnesses, and medicines. They will order simple tests to check how well your kidneys are working.

Tests that may be done

• Blood test to measure creatinine (a waste product that shows how your kidneys are filtering)
• Urine test to check for blood, protein, or signs of infection
• An ultrasound scan of your kidneys to look for a blockage
• Sometimes a small tube (catheter) to measure how much urine your bladder holds

What to expect at your appointment

You may need to stay in hospital for observation. The doctor will watch how much urine you pass and do regular blood tests. This helps them adjust your treatment quickly.

Treatment

The main treatment for AKI is to treat the cause. Your care team will give you fluids into a vein if you are dehydrated, stop any medicines that might be harming your kidneys, and monitor your kidney function closely.

Self-care at home

• Follow your doctor's advice about drinking fluids (you may be told to drink more or less than usual)
• Do not take any new medicines, vitamins, or herbal remedies without checking with your doctor or pharmacist first
• Tell your doctor if your urine output goes down or you feel worse

Medical treatments

Depending on the cause, treatment may include fluids through a drip, diuretic (water) tablets to help remove extra fluid, or treatment for the underlying infection or blockage. If your kidneys are not working at all for a period of time, you may need dialysis. Dialysis is a machine that does the filters' job for you. It is temporary in many cases, and the need for it is reviewed often. Medicines are chosen carefully to be safe for your kidneys.

When is surgery considered?

If a blockage is causing your AKI, a urologist may pass a small tube to unblock it or perform a procedure to remove the cause. This is not needed for most people.

Living with this condition

Recovery from AKI takes time. After leaving hospital, you will need regular blood tests to check your kidney function. It may take weeks or months, and some people are left with lasting kidney damage. Your doctor will set a plan for follow-up.

Lifestyle tips

• Stop smoking, as this harms blood vessels, including those in the kidneys
• Limit alcohol to low-risk levels (no more than 14 units a week for most people)
• Keep up with your routine check-ups if you have diabetes or high blood pressure
• Make sure you stay hydrated, but don't overdo it — ask your doctor what fluid goal is right for you

Diet and exercise

A kidney-friendly diet usually means eating a balanced diet and not adding extra salt. If your kidney function is low, you may need to limit potassium and phosphorus. Ask to speak to a dietitian. Light physical activity, like walking, is fine as you recover — but listen to your body and rest when tired.

Mental health and emotional wellbeing

Going through a serious kidney injury can feel scary. It’s normal to feel anxious or low during recovery. Talk to your doctor about these feelings. Help is available.

Prevention

You cannot always prevent AKI, but you can lower your risk. The most important step is to avoid dehydration and to keep conditions like diabetes and high blood pressure under control. Always check with your doctor before starting any new medicine, especially painkillers, and before taking herbal supplements.

Vaccines

It's especially important to get your flu and pneumonia vaccines if you have kidney disease or another long-term condition. Vaccines help prevent infections that could strain your kidneys.

Screening programmes

If you have risk factors such as diabetes or high blood pressure, your doctor may already be checking your kidney function with blood and urine tests. Make sure you attend those checks.

Complications

If left untreated

• Permanent kidney damage that can lead to chronic kidney disease (a long-term decrease in kidney function)
• Fluid buildup in the body causing swelling and trouble breathing
• High potassium levels in the blood, which can be dangerous for the heart
• Heart and blood vessel problems
• In severe cases, kidney failure that needs long-term support with dialysis

Long-term outlook

The outlook for AKI is often good. Many people recover fully with prompt treatment. If your kidneys do not fully recover, treatments can help you live a full life. Your healthcare team will support you at every step, and you will have regular checks to keep your kidneys as healthy as possible.

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