Acute Kidney Injury
Acute kidney injury (AKI), also known as acute renal failure, is the sudden loss of kidney function from any cause, where the kidneys rapidly become unable to filter waste products from the blood. As a result, harmful wastes accumulate, posing serious risks to health.
AKI can develop within hours to days and is most common in hospitalized patients, especially those in intensive care. Although AKI can be life-threatening and often requires intensive treatment, it is typically reversible. With proper care, most people regain normal or nearly normal kidney function.
Acute Kidney Injury Symptoms
- Decreased Urine Output: Often reduced, though in some cases, urine output may remain normal.
- Fluid Retention: Leads to swelling, particularly in the feet, legs and other areas of the body.
- Breathlessness: Fluid buildup can impact lung function, causing shortness of breath.
- Drowsiness: Accumulation of toxins can lead to increased drowsiness or lethargy.
- Fatigue: Waste buildup in the blood causes persistent tiredness and low energy.
- Confusion: Toxin accumulation affects mental clarity, sometimes leading to disorientation.
- Seizures or coma: In severe cases, the buildup of waste products can cause seizures or even coma.
Sometimes, acute kidney injury shows no visible symptoms and is only detected through routine lab tests conducted for other reasons.
Acute Kidney Injury Causes
Acute kidney injury can occur due to
- Decreased Blood Flow to the Kidneys (Pre-renal):
- Direct Kidney Damage (Renal)
- Urinary Obstruction (Post-renal)
Decreased Blood Flow to the Kidneys (Pre-renal)
- Blood loss from major bleeding
- Dehydration (sunstroke, diarrhea)
- Blood pressure medications (ACE inhibitors etc)
- Infection
- Liver injury
- Allergy to drugs
Direct Kidney Damage (Renal):
- Blood clots in the veins and arteries of the kidneys
- Cholesterol deposits that block blood flow in the kidneys
- Glomerulonephritis
- Vasculitis, an inflammation of small blood vessels
- Infection
- Medications like chemotherapy drugs, antibiotics, radiocontrast agents
- Multiple myeloma, a cancer of the plasma cells
- Toxins like heavy metals
Urinary Obstruction (Post-renal):
- Kidney stones
- Cancers of bladder, prostate, cervix, colon
- Nerve damage involving the nerves that control the bladder
Acute Kidney Injury Risk Factors
- Hospitalization, especially for serious conditions requiring intensive care
- Advanced age (low GFR to start with)
- Vascular disease
- Diabetes
- Hypertension
- Heart injury
- Pre existing kidney disease
- Liver disease
Acute Kidney Injury Stages
Acute kidney injury is categorized into three stages based on the degree of kidney dysfunction:
- Stage 1: Mild increase in creatinine levels or a slight decrease in urine output, indicating early kidney stress.
- Stage 2: Moderate elevation in creatinine with more significant reduction in kidney function.
- Stage 3: Severe loss of kidney function, often requiring dialysis to manage waste buildup.
Recognizing these stages is crucial for guiding treatment and determining the urgency of intervention.
Acute Kidney Injury Criteria
The diagnosis of acute kidney injury (AKI) is based on specific changes in serum creatinine levels or urine output:
- Serum Creatinine:: A rise of 0.3 mg/dL or more within 48 hours, or an increase to 1.5 times the baseline value, indicates kidney stress.
- Urine Output:: Less than 0.5 ml/kg/hr for 6 hours or longer suggests reduced kidney function.
These criteria are essential for assessing the severity of AKI and guiding the appropriate treatment approach.
Acute Kidney Injury Complications
Acute Kidney Injury can lead to several serious complications if not properly managed:
- Fluid overload: Buildup of fluid in the lungs, which can cause shortness of breath.
- Electrolyte abnormalities: Derangements of potassium, sodium, calcium, magnesium, pH, acid balance, lactic acid are usually seen
- Permanent kidney damage: Rarely, AKI can cause permanent kidney loss of function, or end-stage renal disease. People with end-stage renal disease require either life-long dialysis or a kidney transplant to survive
- Death: Acute kidney injury can lead to loss of kidney function and, ultimately, death. The risk of death is higher in people who had kidney problems before acute kidney injury.
Acute Kidney Injury Treatment
Treatment for acute kidney injury (AKI) generally requires hospitalization to closely monitor and support kidney recovery. The duration of stay depends on the underlying cause and the kidneys' response to treatment. Treatment primarily focuses on addressing the cause of kidney injury and managing complications as the kidneys heal.
1. Treating the Underlying Cause
The first step in AKI treatment is identifying and addressing the illness or injury that initially damaged the kidneys. Specific treatment options depend on the underlying cause of the kidney injury.
2. Managing Complications During Recovery
While the kidneys heal, additional treatments may be necessary to prevent complications and support kidney function:
- Fluid Balance: If AKI is due to low blood volume, intravenous (IV) fluids may be administered to restore hydration. Conversely, if fluid overload is an issue, diuretics may be used to remove excess water and reduce swelling in the arms and legs.
- Potassium Control: When the kidneys can't filter potassium effectively, potassium binders may be prescribed to prevent hyperkalemia, which could lead to dangerous heart arrhythmias or even cardiac arrest.
- Calcium Restoration: In cases of low blood calcium, calcium infusions may be given to prevent complications like muscle cramps or cardiac issues.
- Dialysis: If toxins and excess fluids build up in the blood, temporary dialysis may be required to assist in their removal while the kidneys recover. Dialysis also helps to manage high potassium levels. During dialysis, a machine pumps blood through an artificial kidney (dialyzer) to filter waste before returning it to the body.
Depending on the severity of AKI and patient needs, several dialysis modalities may be selected:
- Hemodialysis (HD)
- Slow low efficiency hemodialysis (SLED)
- Peritoneal dialysis (PD)
- Extended daily diafiltration (EDDf)
- Continuous renal replacement therapy (CRRT)
This structured approach to treatment helps support kidney function, manage complications, and maximize the chances of recovery.
If you’re experiencing symptoms of Acute Kidney Injury or have been diagnosed with a related issue, it is essential to seek specialized care.
Dr. Kamal Kiran offers expert treatment and personalized care plans to help manage your condition and improve your quality of life. Trust his expertise for top-notch nephrology services tailored to your unique needs.
Tests
- Urine tests: Analyzing a sample of the urine, may reveal abnormalities that suggest the cause of kidney injury
- Blood tests: A sample of the blood may reveal rapidly rising levels of urea and creatinine — two substances used to measure kidney function. Other blood tests maybe done to look for electrolyte abnormalities, acidosis, sepsis, antibodies etc
- Imaging tests: RImaging tests such as ultrasound and computerized tomography may be used to help the doctor to assess the extent of damage to the kidneys
- Removing a sample of kidney tissue for testing: In some situations, the doctor may recommend a kidney biopsy to remove a small sample of kidney tissue for lab testing.
Acute Kidney Injury Medications
Medications play a vital role in managing AKI and its associated complications:
- Diuretics: Used to control fluid levels, especially in cases of fluid overload.
- Potassium Binders: Help prevent hyperkalemia (high potassium levels), reducing the risk of heart complications.
- Calcium Supplements: Correct low calcium levels to prevent issues such as muscle cramps and cardiac complications.
- Vasopressors Administered in cases of low blood pressure to enhance kidney perfusion.
These medications are essential for stabilizing kidney function and managing the effects of AKI.