What are the pre-renal causes of acute kidney injury (AKI) or impaired renal function?

From the Guidelines

Pre-renal causes of kidney failure are primarily due to reduced blood flow to the kidneys, often resulting from dehydration, volume depletion, cardiovascular problems, hypotension, or renal artery issues, and can be reversible if promptly identified and corrected. The most common pre-renal causes include:

• Dehydration from vomiting, diarrhea, excessive sweating, or inadequate fluid intake
• Volume depletion from hemorrhage or burns
• Cardiovascular problems such as heart failure, cardiogenic shock, or arrhythmias that reduce cardiac output
• Hypotension from sepsis or medications like antihypertensives, NSAIDs, or ACE inhibitors/ARBs
• Hepatorenal syndrome in advanced liver disease
• Renal artery problems like stenosis or thrombosis, as noted in the study by 1. These conditions reduce renal perfusion pressure, activating compensatory mechanisms including the renin-angiotensin-aldosterone system and antidiuretic hormone release to conserve water and sodium. According to the study by 1, management should focus on addressing the underlying cause, discontinuing medications that may worsen kidney function, and restoring adequate blood volume and pressure through IV fluids. Treatment strategies may involve:
• Restoring adequate blood volume and pressure through IV fluids (normal saline or lactated Ringer's)
• Addressing the underlying cause of reduced blood flow
• Temporarily discontinuing medications that may worsen kidney function, such as diuretics, beta-blockers, and nephrotoxic drugs, as recommended by 1. Prompt identification and correction of the underlying cause can often reverse pre-renal kidney failure, as the kidney structures remain intact, highlighting the importance of early intervention and management, as emphasized in 1.

From the Research

Pre-Renal Causes of Kidney Failure

• Pre-renal failure is a result of decreased renal perfusion and can be caused by:
  • True hypovolemia, which complicates hemorrhage, gastrointestinal or renal fluid losses 2
  • Sepsis 2
  • Type 1 hepatorenal syndrome (HRS) 2
  • Administration of non-steroidal anti-inflammatory drugs or intravascular radiocontrast agents 2
• Approximately 70% of community-acquired cases of acute kidney injury are attributed to pre-renal causes, often due to decreased renal perfusion associated with low intravascular volume or decreased arterial pressure 3
• Pre-renal failure may be reversible after restoration of renal blood flow, and treatments target the cause of hypoperfusion, with fluid replacement used to treat non-HRS pre-renal failure 2

Mechanisms and Contributing Factors

• Autoregulatory mechanisms can partially compensate renal perfusion reduction to maintain glomerular filtration rate (GFR), but these mechanisms are impaired in patients with pre-existing chronic kidney disease, making them more susceptible to develop acute-on-chronic renal failure 3
• Adrenergic activity and angiotensin II (Ang II) are the dominant hormonal influences that impact the determinants of glomerular filtration, with interactions between individual adrenoreceptors and Ang II being complex and significant 4
• Tubular injury can also activate pre-renal mechanisms via the tubuloglomerular feedback system, with bidirectional regulatory influences occurring between the vasoconstrictor and vasodilatory hormonal systems 4

Treatment and Management

• Fluid replacement is used to treat non-HRS pre-renal failure, while liver transplantation is the ideal treatment for patients with type 1 HRS 2
• Systemic vasoconstrictor therapy with terlipressin, noradrenaline, or midodrine may improve renal function in patients with type 1 HRS waiting for liver transplantation 2
• Lactated Ringer's solution may be a safe choice for IV fluid therapy in patients undergoing kidney transplantation, with less hyperkalemia and acidosis compared to normal saline 5, 6