Overview
(AKI) is a sudden drop in how well the kidneys work. It develops over hours or days, not months. The kidneys can no longer clear waste and extra fluid from the blood.
It usually happens on top of another problem, such as a serious infection, dehydration or a blockage to the flow of urine. It can be life-threatening if it is not treated, but many people recover fully.
Symptoms
Many people have no symptoms when AKI is mild. Others may have:
- Passing much less urine than usual
- Strong thirst
- Feeling or being sick
- Swelling in the feet or legs
- Tiredness, dizziness, confusion or drowsiness
- Breathlessness, especially when lying down
When to see a doctor
If you think you may have AKI, for example because you are passing much less urine or have new swelling of the feet or legs with nausea, get medical help the same day. This matters most if you are 65 or older, have had AKI before, have recently had surgery, have long-term kidney, heart or liver disease, or take anti-inflammatory painkillers, medicines or water tablets.
Causes
AKI happens when the blood flow to the kidneys falls, when the kidneys are damaged directly, or when urine cannot drain out. Common causes include:
- Low blood flow to the kidneys: dehydration, heavy bleeding, very low , a severe infection (sepsis) or major surgery
- Direct damage: infection, contrast dye used in some scans, and some medicines, including anti-inflammatory painkillers, certain and some blood pressure medicines
- A blockage: kidney stones, an enlarged prostate or a tumour
Risk factors
- Age 65 or over
- Having had AKI before
- Recent surgery
- Long-term conditions such as kidney, heart or liver disease, diabetes and high
- Long-term use of certain medicines, including anti-inflammatory painkillers, ACE inhibitors and water tablets
- Using illegal drugs
Complications
Possible complications include:
- A dangerous build-up of potassium and other chemicals in the blood
- Fluid collecting in the body, causing swelling and breathlessness
- A need for for a time
- Lasting kidney damage (chronic kidney disease), more likely after a severe episode or with other long-term illnesses
Prevention
- Drinking enough fluids, especially in hot weather or when vomiting or having diarrhoea, so that urine stays pale
- Keeping and diabetes well controlled
- Asking a doctor or pharmacist before starting any new medicine or supplement, if you are at higher risk
Diagnosis
A blood test measures creatinine, a waste product the kidneys normally remove. A raised level suggests the kidneys are not working well. Blood tests also check potassium and other salts. The doctor will ask about your urine output, check your pulse and , and test a urine sample.
To find the cause, an scan is often used to look for a blockage. An , X-ray or may also be done. In severe or unclear cases a kidney specialist (nephrologist) may be involved.
Treatment
Treatment depends on the cause and how severe it is, and it is often given in hospital. The aim is to treat the cause so that the kidneys can recover.
- Careful control of fluids: a drip if dehydrated, or limiting fluids if the body holds too much
- Treating infection, and stopping or changing medicines that may be harming the kidneys
- Medicines to control , remove extra fluid or lower potassium
- A tube (catheter) to drain the bladder, or surgery, to remove a blockage
- Diet changes as advised, usually less salt and potassium
- , a machine that cleans the blood, for severe cases. It is usually needed for a few days or weeks until the kidneys recover
After recovery, regular blood tests and check-ups are needed to make sure the kidneys are working well.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“If my kidneys were failing I would feel it, so I would know.”What is true?
Fact
Many people have no symptoms, especially when the injury is mild. It is often found on blood tests done during a hospital stay or for another illness. That is why signs such as passing much less urine should never be ignored.
Myth“Painkillers like ibuprofen and diclofenac are safe because you can buy them without a prescription.”What is true?
Fact
Anti-inflammatory painkillers (NSAIDs) are among the medicines that can contribute to kidney injury, especially with long-term use. If you are at higher risk, ask a doctor or pharmacist before starting any painkiller or other new medicine.
Myth“Kidney failure always means dialysis for life.”What is true?
Fact
In AKI the loss of kidney function is sudden and often temporary. Many people recover fully within a few weeks, and serious cases can take months. When dialysis is needed it is usually for a few days or weeks until the kidneys recover, although a few people are left with permanent damage.
Myth“Once the symptoms are gone and the tests look better, there is nothing more to do.”What is true?
Fact
Some people are left with lasting kidney damage after AKI, more so if it was severe or they have other long-term illnesses. Regular blood tests and check-ups are needed after recovery.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
Can the kidneys recover after acute kidney injury?
Often, yes. Many people recover fully within a few weeks, though more serious cases can take several months. Some people are left with lasting kidney damage, so follow-up blood tests after recovery are important.
Is acute kidney injury the same as chronic kidney disease?
No. AKI is sudden and often temporary, and develops over hours or days. Chronic kidney disease develops slowly over months or years and is lifelong. However, a severe episode of AKI can sometimes leave chronic kidney disease behind.
Does everyone with acute kidney injury need dialysis?
No. Dialysis is used in severe cases, for example when potassium in the blood becomes dangerously high or the body holds too much fluid. It is usually needed for a few days or weeks until the kidneys recover, but a few people with severe damage need it long term.
Can vomiting and diarrhoea harm my kidneys?
Yes. Losing a lot of fluid can reduce the blood flow to the kidneys and lead to AKI. Sip fluids often, and get medical help if you cannot keep fluids down or are passing much less urine. If you take medicines for blood pressure, fluid or pain, ask a doctor or pharmacist what to do while you are unwell.
