Overview
Acute kidney injury(AKI) refers to a medical condition whereby the kidneys suddenly stop functioning properly.Usually, there is a sudden and often reversible reduction in the functioning of the kidneys. Glomerular filtration rate(GFR) is one of the parameters used to measure kidney function.
Earlier on, this condition used to be referred to as acute kidney failure(AKF) or acute renal failure(ARF). If left untreated, AKI can lead to death.
Facts & Statistics
- Most common in hospitalized patients, especially those hat require intensive care.
- In the United States, 1 in every 100 of all hospital admissions have AKI.
- AKI contributes go extended hospital stay and patient morbidity.
- If left untreated, AKI has a significant morbidity and mortality.
- In-hospital mortality rate for AKI is 40%-50% while for ICU patients, mortality rate is more that 50%.
Risk Factors
What are the risk factors for AKI?
It should be noted that that sick or hospitalized individuals have a higher risk of developing AKI.
The following are other risk factors:
- Age. Older individuals who are aged 65 years and above.
- History or presence of a kidney problem such as chronic kidney disease
- Long-term diseases. Foe example, diabetes.
- Sepsis.
- Hypertension. People with severe, uncontrolled blood pressure are at risk.
- Severe dehydration.
- Intake of NSAIDs such as ibuprofen.
- Anti-hypertensives such as diuretics.
Stages
What are the stages of AKI?
Normal GFR is usually estimated at 125 ml/min.
- Stage I: GFR is 90 ml/min or more
- Stage II: GFR is 60-89 ml/min
- Stage IIIa: GFR is 45-59 ml/min
- Stage IIIb: GFR is 30-44 ml/min
- Stage IV: GFR is 15-29 ml/min
- Stage V: GFR is lower than 15 ml/min
Causes
What are the causes of AKI?
Several factors have been identified as causes of AKI. These are:
- Insufficient supply of blood to kidneys(pre-renal).
- Direct injury to kidneys(intra-renal)
- Blockage in the urinary tract(post-renal)
Pre-renal AKI
Some medical conditions which restrict flow of blood to the kidneys include;
- Heart disease
- Low blood pressure
- Severe haemorrhage
- Severe burns
- Severe dehydration
- Severe diarrhea
- Severe allergy
Intra-renal AKI
This is due to damage to the kidneys, which can be as a result of:
- Diseases such as glomerulonephritis.
- Blood clots in kidneys.
- Blood vessel disorders such as vasculitis.
Post-renal AKI
Due to blockage of ureters. Some of the conditions responsible include:
- Renal stones
- Enlarged prostate gland
Signs & Symptoms
What are the signs and symptoms of AKI?
- Reduced urine output
- Tiredness
- Confussion
- Nausea
- Weakness
- Irregular heartbeats
- Edema
- Abdominal pain
- Loss of appetite
- Chest pain
- Seizures
Tests for Diagnosis
What are the tests for diagnosing AKI?
- Blood tests. These measure substances such as creatinine, potassium, sodium and urea nitrogen.
- Urine output measures.
- Urine tests.
- Kidney biopsy.
- Imaging tests such as CT scans.
Differential Diagnosis
What are some of the differential diagnoses considered to be AKI?
- Hypovolemia
- Low cardiac output
- Urinary tract infection(UTI)
- Urinary obstruction
- Renal calculi
- Acute or chronic kidney disease ( chronic kidney disease)
Treatment and Management
Treatment for AKI is based on cause and severity. Often, treatment for AKI needs hospitalization.
- Anti-hypertensives to regulate blood pressure
- Diuretics for restoring normal fluid balance
- Dialysis for severe AKI
- Medications to control blood potassium levels.
- Catheterization to drain the bladder in cases of blockages.
- Diet. Restrict amount of potassium and edible salt.
Note that for AKI patients, dietary intake of potassium and phosphorous must be monitored, in addition to renal adjustment of certain medications.
In cases where hyperkalemia(high levels of potassium in the blood) develops as a complication related to AKI, potassium must be lowered through:
- Dietary restriction
- Potassium-binding resins
- Dialysis for hyperkalemia that is non-responsive
Complications
What are the complications of AKI?
- Metabolic acidosis
- Edema and pulmonary edema
- Hyperkalemia(high levels of potassium in the blood). This can lead to arrhythmias.
- Hyperphosphatemia.
Organ-related complications:
- Renal: Chronic kidney disease.
- Cardiovascular: Heart failure secondary to fluid overload.
- Neurologic: Lethargy, cognitive impairment and disturbed sleep wake cycle.
- Gastrointestinal: Nausea, vomiting and anorexia.
Death can occur when kidneys stop working.
Prevention
Public education. Patients should be educated that regular NSAID consumption is harmful to kidneys. Apart from this, they should be let to know that non-compliance with blood pressure medications can worsen injury to the kidney.
Health check-ups. Regularly pay visits to specialists such as urologists and nephrologists.