Dr Alvin Ng
Senior Consultant Nephrologist

Bachelor of Medicine and Surgery (Auckland, New Zealand)
Fellow of the Royal Australasian College of Physicians
Fellow of the Academy of Medicine, Singapore (Renal Medicine)

Acute kidney injury (AKI) or acute renal failure, is when your kidneys experience a sudden and often reversible decline in kidney function. When this occurs, the kidneys are not able to eliminate waste products from your blood effectively and have difficulty in maintaining the right balance of salt, acidity and fluid in your body. This will affect the normal functioning of other organs, such as the brain, heart, and lungs. It can range from a minor loss to a complete loss of kidney function.

Symptoms of Acute Kidney Injury

As AKI can occur rapidly, a person will experience various acute kidney injury symptoms, such as reduced urination or no urine flow, fatigue, swelling in legs, ankles and around the eyes, muscle weakness, breathlessness, confusion, nausea, seizures or even coma in severe cases.

In some cases, this disease can occur without any apparent acute kidney injury symptoms and is detected only while a person is hospitalised in an intensive care unit or being treated for a different condition.

Symptoms

Causes of Acute Kidney Injury (AKI)

AKI can be categorised to three main causes:

Pre-renal AKI causes

Reduced blood flow to the
kidneys due to:

Sepsis (severe infection)
Liver failure
Heart failure
Heart attack
Hypovolemia

Intra-renal AKI causes

Direct damage to the
kidneys due to:

Severe kidney infections
Toxic medications affecting the kidneys, such as anti-inflammatory drugs, antibiotics, or proton pump inhibitors
Tumour lysis syndrome
Traumatic injuries such as blunt-force trauma and crush injuries
Rhabdomyolysis

Post-renal AKI causes

Obstruction in the
urinary tract due to:

Prostate cancer
Enlarged prostate
Neurogenic bladder
Bladder or kidney stones
Bladder cancer
Renal artery thrombosis

Symptoms of Acute Kidney Injury

Due to the instantaneous nature of acute kidney injury, a person may develop multiple acute kidney injury symptoms rapidly. The symptoms they experience can include a lack of urine or no urine flow, swelling in legs, ankles and around the eyes, fatigue, tiredness, breathlessness, confusion, nausea, seizures or even coma in severe cases.

In some cases, acute kidney injury can occur without any apparent symptoms and is detected only while a person is hospitalised or being treated for a different condition.

Risk Factors of Acute Kidney Injury (AKI)

The elderly
Those who suffer from pre-existing kidney diseases
Those who have a long-term disease such as heart failure, liver failure or diabetes
Those who have severe infection or sepsis (blood poisoning),
Those who have a urinary blockage
Those taking certain medications, especially in excess or were unwell when taking regular doses of medicine.

Diagnosis

Blood tests (e.g., creatinine, blood urea nitrogen) to measure kidney function.
Urine tests to check for abnormalities.
Imaging studies (e.g., ultrasound or CT scans) to identify structural issues in the kidneys or urinary tract.

Treatment Options

If left untreated, acute kidney injury can develop into many other complications, all of which may be fatal. For example, the rapid build-up of toxins can cause pulmonary oedema or hyperkalemia, which can then lead to heart rhythm problems or respiratory failure.

Acute kidney injury treatment depends on the underlying cause:

Fluid and electrolyte management: Correcting dehydration or overload
Medications: To control blood pressure, reduce swelling, or treat infections
Dialysis: In severe cases, temporary dialysis may be required to filter waste until kidney function recovers.

Early detection and intervention can often lead to complete recovery, but if left untreated, AKI can lead to chronic kidney disease or permanent loss of kidney function.

What are the differences between AKI vs CKD?

CKD and AKI are both conditions that affect the kidneys. They may seem similar, but their causes, onset, and duration differ.

Onset and Duration:
- Chronic Kidney Disease: CKD is a prolonged condition that develops gradually. It may take months or years for symptoms to become noticeable. CKD is often the result of underlying health conditions such as diabetes or high blood pressure. Once kidneys are damaged, the condition is usually irreversible, and the aim of treatment is to slow the progression of the disease.
- Acute Kidney Injury: AKI, on the other hand, is a sudden and often reversible condition where the kidneys lose their function over a short period. It can develop rapidly, sometimes within hours or days, and is often triggered by severe infections, dehydration, or certain medications.

Causes:
- Chronic Kidney Disease: CKD is commonly caused by conditions that gradually damage the kidneys over an extended period. Causes are often diabetes, high blood pressure, glomerulonephritis, and polycystic kidney disease.
- Acute Kidney Injury: AKI is usually caused by a sudden drop in blood flow to the kidneys (prerenal), direct damage to the kidneys (intrinsic renal), or obstruction of urine flow (postrenal). Common causes include severe infections, dehydration, kidney infections, and certain medications.

Do you have a question about your kidney or medical condition?

Reach out to us for a consultation with Dr Alvin Ng.

Our Acute Kidney Injury Specialist

Dr Alvin Ng (黄国雄医生)

Bachelor of Medicine and Surgery (Auckland, New Zealand)
Fellow of the Royal Australasian College of Physicians
Fellow of the Academy of Medicine, Singapore (Renal Medicine)

Dr Alvin Ng is a senior consultant nephrologist with over two decades of experience in kidney care. Prior to setting up his own practice, Dr Ng was the Director of Peritoneal Dialysis at Changi General Hospital and an executive committee member of the Singapore Society of Nephrology. He has held teaching appointments for medical students and residents; and is also a recipient of various service awards – a testament to the quality of care he provides.