What are the causes of Acute Kidney Injury (AKI)?

From the Guidelines

Acute Kidney Injury (AKI) is primarily caused by prerenal, renal, or postrenal factors.

Causes of AKI

• Prerenal factors: include impaired blood flow from any cause, such as hypotension, hypovolemia, decreased cardiac output, or renal artery occlusion 1.
• Renal causes: include any disease that damages renal parenchyma, such as vasculitis, acute tubular necrosis, glomerulonephritis, interstitial nephritis, renal infection or infiltration, drugs, and toxins 1.
• Postrenal AKI: results from ureteral, bladder, or urethral obstruction, although this accounts for less than 3% of AKI cases 1. Other risk factors for AKI include pre-existing chronic kidney disease (CKD), the use of medications that cause kidney injury, such as nonsteroidal anti-inflammatory drugs, and the use of medications that alter renal blood flow and intrarenal hemodynamics, such as diuretics, ACE inhibitors, and angiotensin receptor blockers (ARBs) 1.

Diagnosis and Classification of AKI

AKI is diagnosed by a rapid increase in serum creatinine, which is also reflected as a rapid decrease in estimated glomerular filtration rate (eGFR), over a relatively short period of time 1. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines classify AKI into three stages based on the increase in serum creatinine and urine output 1.

Importance of Timely Identification and Treatment

Timely identification and treatment of AKI are crucial because AKI is associated with increased risks of progressive CKD and other poor health outcomes 1.

From the Research

Causes of Acute Kidney Injury (AKI)

The causes of AKI can be conceptually classified into three general categories:

• Prerenal causes
• Intrarenal causes
• Postrenal causes 2, 3, 4

Prerenal Causes

Prerenal causes are related to decreased blood flow to the kidneys, which can be caused by:

• Hypovolaemic shock 5
• Sepsis 5, 6
• Dehydration 5

Intrarenal Causes

Intrarenal causes are related to damage to the kidney tissue itself, which can be caused by:

• Acute tubular necrosis caused by ischemia or nephrotoxicity 2
• Nephrotoxicity caused by certain medications or substances 5, 6
• Infections 5

Postrenal Causes

Postrenal causes are related to obstruction of the urinary tract, which can be caused by:

• Kidney stones 3
• Tumors 3

Other Causes

Other causes of AKI include:

• Invasive procedures 5
• Trauma 5, 6
• Certain medical conditions, such as cardiovascular disease 4