Prerenal AKI (e.g., dehydration, hypovolemia): This is often the most common cause of AKI, especially in hospitalized patients. It occurs when there's a decrease in blood flow to the kidneys, which can be due to various factors such as dehydration, blood loss, or heart failure. The kidneys themselves are structurally normal, but the reduced blood flow leads to a decrease in glomerular filtration rate (GFR).

Acute Tubular Necrosis (ATN): This is a common cause of intrinsic AKI, often resulting from ischemia or nephrotoxicity (e.g., certain medications like aminoglycosides or contrast agents). ATN leads to damage of the tubular cells of the kidneys, impairing their ability to reabsorb and secrete substances.
Postrenal AKI (obstruction): This occurs when there's a blockage in the urinary tract, preventing the normal flow of urine. Common causes include kidney stones, bladder outlet obstruction (e.g., due to an enlarged prostate), and tumors.
Medication-induced AKI: Various medications can cause AKI through different mechanisms, including NSAIDs (which can reduce renal blood flow), certain antibiotics, and chemotherapeutic agents.

Rhabdomyolysis: This condition, characterized by the breakdown of muscle tissue, can lead to AKI due to the release of myoglobin, which is toxic to the kidneys. It's crucial to identify and treat promptly to prevent severe kidney damage.
Sepsis: Sepsis can cause AKI through a combination of hypoperfusion and the direct effects of inflammatory mediators on the kidneys. Early recognition and management of sepsis are critical to prevent organ failure.
Atheroembolic disease: This condition involves the release of cholesterol crystals from atherosclerotic plaques, which can embolize to the kidneys and cause AKI. It's often seen in patients undergoing vascular procedures or with severe atherosclerosis.

Vasculitis (e.g., ANCA-associated vasculitis): These are autoimmune conditions that can affect the blood vessels of the kidneys, leading to inflammation and damage. They are less common but can be severe and require specific treatment.
Thrombotic microangiopathies (e.g., HUS/TTP): These disorders involve the formation of blood clots in small blood vessels throughout the body, including the kidneys, and can lead to AKI. They are rare but have significant morbidity and mortality if not recognized and treated appropriately.
Glomerulonephritis: This refers to a range of kidney diseases that involve inflammation of the glomeruli. While not all forms are rare, certain types like Goodpasture's syndrome or anti-GBM disease are uncommon and can present with AKI.