Acute Kidney Injury

Acute Kidney Injury (AKI) is when the kidneys suddenly lose their ability to filter waste products from the blood. This impairment leads to the accumulation of toxins in the body and disturbances in fluid and electrolyte balance, which can have profound health implications for the patient.

Epidemiologically, acute kidney injury is a common condition, especially among hospitalized patients. Its incidence increases with age and is more common in individuals with pre-existing chronic conditions such as chronic kidney disease, diabetes mellitus, and heart failure. Patients in intensive care units are at higher risk of developing AKI due to the severity of their illnesses and the aggressive treatments they undergo.

The pathophysiology of acute kidney injury involves three primary mechanisms: prerenal, intrinsic renal, and postrenal AKI. Prerenal AKI is caused by decreased blood flow to the kidneys, which can result from dehydration, hypotension, or heart failure. Intrinsic renal (intrarenal) AKI results from direct kidney damage from medications, infections, or autoimmune diseases. Postrenal AKI is caused by an obstruction in the urinary tract, such as from stones or tumors.

The causes of acute kidney injury are varied and include dehydration, shock, nephrotoxic substances (such as nonsteroidal anti-inflammatory drugs and antibiotics), infections, autoimmune diseases, and urinary tract obstructions. Risk factors include age, pre-existing kidney disease, heart failure, diabetes mellitus, and the use of nephrotoxic drugs.

Symptoms of acute kidney injury include reduced urine output, fluid retention, which can manifest as swelling in the legs, shortness of breath due to fluid buildup in the lungs, fatigue, nausea, confusion, and, in severe cases, coma.

Differential diagnosis of acute kidney injury is essential to distinguish it from other conditions that can cause similar symptoms, such as chronic kidney disease, acute tubular necrosis, acute interstitial nephritis, and urinary tract obstructions.

Complications of acute kidney injury can be severe and include hyperkalemia, metabolic acidosis, fluid overload, hyponatremia, hypocalcemia, and an increased risk of infections. Long-term, patients with AKI may develop chronic kidney disease or even renal failure requiring dialysis.

Treating acute kidney injury involves addressing the underlying causes, restoring fluid and electrolyte balance, and supporting renal function. In cases of severe hyperkalemia or acute oliguria, dialysis may be necessary. Management also includes monitoring fluid intake and avoiding nephrotoxic drugs.

Laboratory tests play a central role in diagnosing and monitoring acute kidney injury. Critical tests include measuring blood levels of creatinine and urea, which are indicators of kidney function. An increase in these values suggests a reduction in kidney filtration. Measuring electrolytes (sodium, potassium, calcium) is crucial in assessing possible imbalances. Urinalysis can reveal the presence of protein, blood, or casts, indicating kidney damage.

Monitoring patients with acute kidney injury involves regular clinical evaluations and repeated laboratory tests to track kidney function and fluid and electrolyte balance. Continuous monitoring is crucial to detect potential complications and adjust treatment as the disease progresses.

This article belongs to a new series on our blog that covers all fields of health! We present information on the most frequent pathological conditions in a comprehensive, clear, understandable, but always scientifically documented way so you can know and protect the most crucial good: your health!

Ioannis Sideris, Medical Doctor