Acute Kidney Injury

Causes and Symptoms

What is Acute Kidney Injury (AKI)?

In acute kidney injury (previously acute renal failure) reduction or loss of kidney functions occur within a short period (over hours, days or weeks) and is temporary, and usually reversible.

What causes acute kidney injury?

There are many causes of AKI. Common causes include:

1. Reduced blood supply to the kidneys: severe dehydration due to diarrhea, blood loss, burns or fall in blood pressure.
2. Severe infection, serious illness or after a major operation.
3. Sudden blockage of the passage of urine : Kidney stones is the most common cause of urinary tract obstructions.
4. Other causes: Falciparum malaria, leptospirosis, snake bite, certain kidney diseases, pregnancy, complications and side effects of some medications (NSAIDs, aminoglycosides, radio contrast, certain herbal concoctions.

Symptoms of acute kidney injury

In AKI, due to the sudden interruption in kidney function and rapid accumulation of waste products and disturbances in fluid and electrolyte balance, the patient develops early and significant symptoms.

The type of symptoms and their severity differ from patient to patient. These include:

1. Symptoms due to underlying condition (diarrhea, blood loss, fever, chills, etc.) causing kidney failure;
2. Decreased urine output (urine output may remain normal in a few patients).
3. Swelling of ankles or feet and weight gain due to fluid retention.
4. Loss of appetite, nausea, vomiting, hiccups, fatigue, lethargy and confusion.
5. Severe and life threatening symptoms such as breathlessness, chest pain, convulsions or coma, vomiting of blood and abnormal heart rhythm due to high blood potassium levels.
6. In the early stage of acute kidney failure some patients are symptom- free and the disease is detected incidentally when blood tests are done for other reasons.

Diagnosis

Diagnosis of acute kidney injury

Many patients with acute kidney injury have nonspecific symptoms or are asymptomatic. Therefore, in any setting or condition when AKI may develop or in the case of slightest doubt regarding symptoms, one must always suspect and investigate for acute kidney injury.

Diagnosis is confirmed by blood tests (rise in serum creatinine and blood urea), urine output measurements, urinalysis and ultrasound. In patients with acute kidney injury detailed history, examination and different investigations are performed to evaluate causes, complications and progression of the disease.

Treatment and Prevention

Treatment of acute kidney injury

In most patients, with proper management acute kidney injury can be reversed.

However delay or improper treatment of severe acute kidney failure can be life-threatening.

Major steps for the management of acute kidney injury are:

1. Correction or treatment of the causes of kidney injury.
2. Drug therapy and supportive measures.
3. Dietary advice.
4. Dialysis.

1. Correcting/ treating the causes of kidney injury:

• Identification and treatment of the underlying cause is the most important aspect of management of acute kidney injury.
• Specific treatment of underlying causes such as hypotension, infection, urinary tract obstruction etc. is essential for recovery from kidney failure.
• Such therapy prevents further damage to the kidney and subsequently allows it to recover.

2. Drug therapy and supportive measures:

• The goal is to support the kidneys and to prevent or treat any complications.
• Treatment of infections and avoidance of drugs which are toxic and harmful to the kidney (e.g. NSAIDs).

The use of diuretics such as furosemide help to increase the volume of urine and prevent accumulation of fluid in the body especially the lungs which is a cause of breathlessness.

Supportive therapy: drugs are given which help to correct low or high blood pressure, control nausea and vomiting, control blood potassium, reduce breathlessness and prevent or control convulsions.

3. Dietary advice

• Proper dietary restriction prevents or reduces symptoms or complications of acute kidney injury.
• Measurement of fluid intake. Daily fluid intake should be planned, keeping in mind urine volume and body fluid status. Usually, restriction of fluid is necessary to prevent edema and complications such as breathlessness.
• Restriction of potassium intake. Avoid potassium-rich food e.g. fruits, fruit juices, dry fruits etc. to prevent high potassium level in blood (hyperkalemia), which is a very serious and life-threatening complication.
• Restriction of salt intake. Salt restriction helps to reduce thirst, edema and complications such as high blood pressure and breathlessness.
• Provision of adequate nutrition and calories.

4. Dialysis

Short-term replacement of the kidney function by dialysis (artificial kidney) may be necessary in a few patients of acute kidney failure until the kidneys recover their functions.

What is dialysis?

Dialysis is the artificial process to replicate the functions of the damaged kidney. It helps to sustain life in people with severe kidney failure. The most important functions of dialysis are to remove wastes, remove excess fluid and correct acidosis and electrolyte disturbances. There are two main types of dialysis : hemodialysis and peritoneal dialysis.

In AKI, the kidneys usually recover completely with proper treatment.

When is dialysis needed in acute kidney injury?

Dialysis is needed in certain patients with severe forms of acute kidney injury when increasing symptoms and complications occur despite adequate conservative management. Severe fluid overload, uncontrollable hyperkalemia and severe acidosis are the most common indications of dialysis in acute kidney injury.

For how long is dialysis treatment needed in acute kidney injury?

• Certain patients of acute kidney injury need temporary dialysis (hemodialysis or peritoneal dialysis) support till kidney function recovers.
• Patients of acute kidney injury usually recover within 1 - 4 weeks, during which dialysis support may be required.
• Dialysis treatment in AKI is often temporary since the kidneys eventually recover in most cases delaying dialysis because of fear of permanent dialysis can be life-threatening in acute kidney injury.

Prevention of acute kidney injury

• Early treatment of potential causes and frequent check up of kidney function in such patients.
• Prevention of hypotension and its prompt correction.
• Avoidance of nephrotoxic drugs and prompt treatment of infection and reduced urine volume.