Acute Kidney Injury Aki

Overview

Acute kidney injury (AKI) is a sudden drop in kidney function that happens over hours or days. Your kidneys act as your body's filters, removing waste and extra fluid. When they suddenly stop working well, waste can build up in your blood and make you feel unwell. With prompt treatment, this is often reversible.

Yes. AKI is common, especially in people who are already ill in hospital. It affects about 1 in 5 people admitted to hospital at some point during their stay.

Anyone can get AKI, but it is more likely in older adults, people with long-term health conditions like diabetes or high blood pressure, and people already in hospital with a serious infection.

Symptoms

Common symptoms

• Feeling very tired or weak
• Passing less urine than usual
• Swelling in your legs, ankles, or feet
• Shortness of breath
• Confusion or feeling unclear in your thinking
• Nausea or vomiting

Symptoms in children

• Fever and being irritable
• Not wetting nappies as often as usual
• Poor feeding or vomiting
• Swelling of the face, hands, or feet

Symptoms in older adults

• Being unusually confused or drowsy
• Becoming less mobile or more unsteady
• Poor appetite and not drinking enough
• Passing very little urine

Causes

Main causes

• A severe infection or sepsis (the body's extreme response to infection)
• Severe dehydration from vomiting, diarrhoea, or not drinking enough
• Certain medicines, especially some painkillers (like non-steroidal anti-inflammatory medicines) and blood pressure pills — always check with a healthcare professional
• A blockage in the urinary system, such as an enlarged prostate or a kidney stone
• Major surgery or serious injury, especially if there was blood loss

Risk factors

• Being aged 75 or older
• Having diabetes, high blood pressure, or heart failure
• Already having chronic kidney disease
• Being in hospital, especially in intensive care
• Taking multiple medicines that affect the kidneys
• Having liver disease or a weakened immune system

When to see a doctor

See a doctor urgently if:

• If you are producing much less urine than normal, especially overnight
• If you have sudden swelling in your legs, hands, or face
• If you feel unusually confused, drowsy, or breathless

Book a routine appointment if:

• If you feel generally unwell, tired, or have lost your appetite for more than a few days
• If you have a health condition like diabetes or high blood pressure and notice a change in your usual energy or urine output

Diagnosis

AKI is diagnosed with a blood test that checks your creatinine level — a waste product your kidneys should filter out. A rise in creatinine over a short time confirms AKI. A urine test can also help find the cause.

Tests that may be done

• Blood test (creatinine and electrolytes)
• Urine test
• Ultrasound scan of your kidneys if a blockage is suspected
• Blood pressure check
• Sometimes a chest X-ray or other scans

What to expect at your appointment

A doctor or nurse will ask about your recent health, medicines, and how much you have been drinking. They may take blood samples more than once to see the trend. You may need to stay in hospital for a short time, especially if you need fluids through a drip.

Treatment

Treatment focuses on fixing the cause and giving your kidneys time to heal. Many people need fluids through a drip (intravenous fluids) and close monitoring. If you take medicines that can harm the kidneys, your doctor may temporarily stop or change them.

Self-care at home

• Drink enough fluids — but follow your doctor's advice on how much, especially if you have heart failure or swelling
• Avoid medicines like non-steroidal anti-inflammatory painkillers unless a doctor says they are safe for you
• Rest and let your body recover
• Monitor how much urine you pass and report any big changes

Medical treatments

In hospital, treatment may include intravenous fluids, medicines to manage blood pressure or balance salts, and treating the underlying infection or blockage. In severe cases, a kidney replacement therapy called dialysis (a machine that filters the blood) may be used for a short time, but this is not needed for most people. Always speak to your healthcare team before taking any new medicine, including over-the-counter remedies.

When is surgery considered?

If a blockage in the urinary system (such as an enlarged prostate or a kidney stone) is causing AKI, a urologist may need to insert a small tube called a stent to drain urine. Surgery itself is rarely needed as an emergency, but it may be planned once you are stable.

Living with this condition

After an AKI, your kidneys usually recover gradually over days or weeks. You will have regular blood tests to check kidney function. In the meantime, look after yourself, take medicines exactly as prescribed, and keep any follow-up appointments.

Lifestyle tips

• Stay well hydrated — but follow your doctor's fluid advice
• Stay active with gentle movement like walking, as tolerated
• Avoid alcohol while your kidneys are recovering
• Ask your pharmacist or GP before taking any over-the-counter medicines
• Consider wearing a medical alert item if your kidney function is reduced

Diet and exercise

You do not usually need a special diet after a single AKI unless a kidney specialist advises one. Eat a balanced diet with fruit, vegetables and whole grains. Avoid extremely salty food. Gentle exercise like walking or gentle cycling is good for recovery, but stop if you feel dizzy or breathless.

Mental health and emotional wellbeing

It can be worrying to learn your kidneys have been injured. You may feel anxious, low, or worried about the future. These feelings are normal. Talk to your GP or kidney team if you are struggling. If you have thoughts of harming yourself, reach out for crisis support immediately.

Prevention

Not always, but many cases can be prevented. Staying well hydrated during illness, avoiding high-risk medicines, and keeping chronic conditions like diabetes well controlled all reduce your risk. If you are in hospital, your care team will monitor your kidneys closely.

Vaccines

Keeping up to date with recommended vaccinations — such as flu and COVID-19 — can help prevent infections that could trigger AKI. This is especially important if you have chronic kidney disease. Ask your GP which vaccines they recommend.

Screening programmes

There is no routine screening for AKI in healthy people. But if you have long-term conditions or are admitted to hospital, your kidney function will be checked with blood tests.

Complications

If left untreated

• Worsening kidney failure that may need temporary dialysis
• Fluid build-up in the lungs, causing severe breathlessness
• Chronic kidney disease that develops after recovery
• Damage to other organs like the heart or brain

Long-term outlook

The good news is that most people recover fully from AKI, especially when it is caught early and the cause is treated. A small number of people have persistent kidney damage and need long-term follow-up, but even then, many live well with the right support. Recovery can take time — be patient with your body.

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