Acute kidney injury

Overview

• Acute kidney injury (acute renal failure) occurs when the kidneys suddenly decrease or lose their function, making them unable to filter waste products from the blood, which allows toxic waste to accumulate and pose a danger to the patient's health.
• Acute kidney injury typically progresses rapidly within a few hours or days. It is common in hospitalized patients, particularly critically ill patients admitted to the Intensive Care Unit (ICU). About 5% of hospitalized patients and 40% to 60% of ICU patients experience acute kidney injury.
• Acute kidney injury can be fatal and requires intensive treatment. However, it can recover normal or near-normal kidney function if treated promptly.

Symptoms of Acute Kidney Injury

• Decreased urine output, although urine volume sometimes remains normal.
• Edema, usually in the legs, or generalized edema in severe cases.
• Possible shortness of breath, fatigue, confusion, nausea, and muscle weakness.
• Seizures or coma in severe cases.
• Sometimes acute kidney injury causes no symptoms and is discovered incidentally through tests performed for another reason.
• Blood tests: decreased kidney function.

Causes of Acute Kidney Injury?

Acute kidney injury can occur when:

• There is a condition reducing blood flow to the kidneys, also known as pre-renal causes.
• Damage directly affects the kidneys, also known as intrinsic renal causes.
• The urinary drainage tract of the kidneys (ureters, urethra) is obstructed, preventing urine and waste products from leaving the body, known as post-renal causes.

Decreased Blood Flow to the Kidneys

• Severe dehydration, loss of body fluids, blood loss.
• Severe burns.
• Heart disease, use of blood pressure medications.
• Myocardial infarction causing cardiogenic shock, hypotension.
• Severe infection, liver failure.
• Severe anaphylactic reaction.

Direct Damage to the Kidneys

• Acute glomerulonephritis.
• Hemolytic uremic syndrome (a condition caused by the early destruction of red blood cells).
• Systemic diseases such as lupus.
• Certain chemotherapy drugs, antibiotics, and contrast media (used in CT scans).
• Toxins: grass carp bile, heavy metals, and cocaine.
• Breakdown of skeletal muscle tissue (rhabdomyolysis) leading to kidney damage from toxins released by muscle tissue destruction.
• Breakdown of tumor cells (tumor lysis syndrome), leading to the release of toxins that can cause kidney damage.

Obstruction of the Urinary Drainage Tract

• Ureteral stones, urethral stones.
• Cervical cancer compressing the ureters.
• Colon cancer compressing the ureters.
• Prostate enlargement, prostate cancer, bladder cancer.

Who is More Vulnerable to Acute Renal Failure?

Factors that can increase the risk of acute kidney injury include:

• Hospitalization, especially for critically ill patients requiring admission to the Intensive Care Unit.
• Elderly patients with multiple pre-existing underlying conditions: kidney disease, diabetes, hypertension, heart failure, etc.

Complications of Acute Renal Failure?

Cardiovascular complications:

- Circulatory overload causing dyspnea, acute pulmonary edema.

• Causing hypertension, heart failure, cardiac arrhythmias, myocardial infarction.
• Pericarditis, pericardial effusion, cardiac tamponade.
• Electrolyte disorders: hyperkalemia, hyponatremia, hypocalcemia, etc.

- Acid-base disorders: the body's blood becomes more acidic.

- Neurological complications: confusion, seizures.

- Gastrointestinal issues: nausea, loss of appetite, vomiting, gastrointestinal bleeding.

- Infections: pneumonia, urinary tract infections, sepsis. Consequences of using multiple intravenous lines, mechanical ventilation, etc.

- Permanent kidney damage: acute renal failure can cause permanent loss of kidney function.

- Death: Acute renal failure can lead to loss of kidney function and ultimately death.

How is Acute Renal Failure Diagnosed?

When signs and symptoms suggest acute renal failure, the physician will order several tests for definitive diagnosis and severity assessment:

• Blood tests: urea and creatinine increase rapidly in acute kidney injury.
• 24-hour urine volume measurement: decreased, potentially leading to anuria (urine volume ≤ 100ml/24 hours.
• Urinalysis: proteinuria.
• Diagnostic imaging: abdominal ultrasound or abdominal CT scan to assess urinary tract injuries.

Treatment

• Most cases of acute kidney injury require hospital treatment. The duration of hospital stay depends on the underlying cause of the acute kidney injury and the extent of kidney recovery.

Treating the underlying cause of the patient's kidney injury

• Treating acute kidney injury by identifying the primary disease or injury causing renal failure. Treatment options depend on the cause of renal failure.
• Treating complications until the patient's kidneys recover

Adjusting body fluid balance

• If acute kidney injury is due to fluid depletion, doctors will administer intravenous fluids to compensate for the fluid deficit.
• In other cases, acute kidney injury may lead to swelling in the hands and feet. In such cases, the physician may use diuretics or employ renal replacement therapies (commonly called dialysis) to excrete excess fluid from the body.

Managing hyperkalemia

During acute kidney injury, blood potassium levels can rise. Elevated potassium can cause dangerous, life-threatening cardiac arrhythmias. Therefore, treatment is required to bring blood potassium back to normal levels.

Supplementing blood calcium if necessary

Dialysis to remove toxins or excess fluid from the patient's blood:

• If toxins accumulate in the blood to a severe degree and medication treatment is unsuccessful, the patient requires dialysis (intermittent hemodialysis or continuous renal replacement therapy) to help remove potassium, toxins, and excess fluid from the body while awaiting the recovery of kidney function.
• During dialysis, the dialysis machine system draws blood out of the body, passes it through a filtration system (filter) to remove toxic waste products and excess fluid, and then returns the blood to the patient's body.

The information above is for reference purposes only and is not intended as medical advice. Please contact your doctor for detailed medical consultation.