Acute kidney injury

Key points

1. Acute kidney injury (AKI) can happen over a few hours, days or weeks.
2. It affects both your kidneys and can range from minor loss of kidney function to complete kidney failure.
3. It is essential that AKI is detected early, as the earlier AKI is picked up the better the chance of your kidneys fully recovering.
4. You are more at risk of AKI if you already have a kidney problem, certain long-term conditions or take certain medications.
5. If you are at increased risk of AKI, you need to take steps to protect your kidneys.

What is acute kidney injury?

Acute kidney injury (AKI) means that your kidneys have suddenly stopped working as well as they used to. This might have happened in the past few hours, days or weeks.

• Acute kidney injury affects both your kidneys and can range from minor loss of kidney function to complete kidney failure.
• If it's not picked up in time, the kidneys can deteriorate quite quickly and shut down. This can lead to permanent damage and can be life threatening if not detected early and treated quickly. 
• AKI is not the same as chronic kidney disease (CKD), in which your kidneys lose their function gradually over a long period of time.
• CKD often goes unnoticed until your kidney function is significantly impaired, and does not get better with time. Read more about chronic kidney disease.

What causes acute kidney injury?

AKI can happen at any age, but it is more common in older people and in people who are in hospital.

You are at increased risk of AKI if you:

• already have a kidney problem, such as chronic kidney disease
• have a long-term disease such as heart failure, liver disease or diabetes
• are dehydrated, eg, when you have diarrhoea, vomiting, or 'gastro' (a tummy bug)
• have an infection 
• have a blockage of one or both of the tubes leading from your kidneys to your bladder, such as kidney stones, or an enlarged prostate 
• are taking some medicines, especially if you take them while you are unwell.

Medicines and acute kidney injury

Taking some medicines increases your risk of getting AKI, especially if you take these medicines while you are dehydrated, or you take a combination of these medicines.

Read more about how you can protect your kidneys.

What are the symptoms of acute kidney injury?

The most common symptoms are:

• passing less urine (pee) than usual
• very concentrated urine, or urine looking yellow/brown/red in colour
• loss of appetite
• feeling sick (nausea) or vomiting
• feeling tired and short of breath
• feeling confused, anxious and restless, or sleepy
• swelling of your legs or other body parts
• pain in your abdomen or lower back.

Sometimes AKI can occur without any symptoms and can only be picked up by a blood test.

How is acute kidney injury diagnosed?

AKI is usually diagnosed from a blood test that measures the level of a substance called creatinine in your blood. High levels of creatinine mean that your kidneys are not getting rid of waste products as well as they should. Sometimes a sample of urine will be checked for blood and protein (dipstick test) and an ultrasound scan of the kidneys will be done to pick up any blockages. 

In rare cases, a kidney biopsy may be needed to work out what is causing AKI. This involves taking a very small sample of tissue from one kidney using a fine needle. The area will be numbed using local anaesthetic.

What happens to my kidneys after the injury?

After AKI you can make a full recovery and have normal kidney function or you can make a partial recovery with lower levels of kidney function. Some people may have permanent kidney damage that requires dialysis.

After AKI your kidney function can continue to recover over time. People who have a history of AKI have a higher risk of chronic kidney disease. It is recommended that you get your kidney function checked out by your doctor every year for the first 3 years following an AKI.

Learn more

The following links provide further information on acute kidney injury. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Acute kidney injury Kidney Health Australia
How to prevent acute kidney injury if you are sick or dehydrated Kidney Health Australia  
Acute kidney injury NHS, UK

References

1. Acute kidney injury J R Coll Physicians Edinb 2013; 43:323–9
2. Acute-on-chronic kidney disease – prevention, diagnosis, management and referral in primary care BPAC, NZ, 2012

Reviewed by

	Dr Eskildsen is the GP Clinical Lead for the ‘Safety in Practice’ programme with WDHB/ADHB. She is also a GP at a high needs practice in central Auckland. Her particular interests are focused on improvement in processes and systems within General Practice to improve safety and quality.