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

From the Guidelines

Renal AKI, or Acute Kidney Injury, is a sudden decline in kidney function that develops over hours to days, and its management should focus on identifying and treating the underlying cause, maintaining fluid balance, and preventing complications, as outlined in the KDIGO guidelines 1. The diagnosis of AKI is based on an increase in serum creatinine by 0.3 mg/dL within 48 hours, or an increase in serum creatinine to 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days, or urine volume less than 0.5 mL/kg/hour for 6 hours 1.

Causes of AKI

• Prerenal causes, such as decreased kidney perfusion due to hypotension, hypovolemia, or decreased cardiac output
• Intrinsic causes, such as direct kidney damage from acute tubular necrosis, glomerulonephritis, or interstitial nephritis
• Postrenal causes, such as urinary tract obstruction

Management of AKI

• Initial treatment involves ensuring adequate hydration while avoiding fluid overload, discontinuing nephrotoxic medications, and correcting electrolyte imbalances
• Specific interventions depend on the cause, such as volume resuscitation with isotonic fluids for prerenal AKI, supportive care for intrinsic AKI, and relieving the obstruction for postrenal AKI
• Monitoring includes tracking urine output, daily weights, serum creatinine, BUN, and electrolytes

Prognosis and Complications

• The prognosis varies based on the cause, severity, and patient's baseline health, with some patients recovering completely while others develop chronic kidney disease
• Early nephrology consultation is recommended for severe AKI, rapidly rising creatinine, or when dialysis might be needed, as indicated in the ACR Appropriateness Criteria for renal failure 1
• Renal replacement therapy (dialysis) may be necessary in severe cases, and the need for dialysis indicates stage 3 AKI, the highest stage of AKI 1

From the Research

Definition and Causes of Acute Kidney Injury (AKI)

• Acute kidney injury (AKI) is defined as an increase in serum creatinine or a decrease in urine output over hours to days 2.
• The underlying cause of AKI can be categorized as prerenal, intrinsic renal, or postrenal 2.

Management and Treatment of AKI

• Initial evaluation and management of AKI in the community setting includes laboratory work-up, medication adjustment, identification and reversal of underlying cause, and referral to appropriate specialty care 2.
• Prevention and early diagnosis are key, as no interventions to improve outcomes of established AKI have yet been developed 3.
• Fluid management should aim for early, rapid restoration of circulatory volume, but should be more limited after the first 24-48 h to avoid volume overload 3.
• Renal replacement therapy should only be started on the basis of hard criteria, but should not be delayed when criteria are met 3.
• Conservative management should first be attempted for patients with AKI, and if conservative management fails, renal replacement therapy or hemodialysis can be used 4.

Use of Furosemide in AKI Management

• Although current guidelines for AKI suggested against the use of furosemide in AKI management, the effect of furosemide on outcomes in real-world clinical settings remains uncertain 5.
• Furosemide administration was associated with improved short-term survival and recovery of renal function in critically ill patients with AKI 5.
• However, the current evidence does not suggest that furosemide can reduce mortality in patients with acute kidney injury 6.
• Furosemide may be useful in achieving fluid balance to facilitate mechanical ventilation according to the lung-protective ventilation strategy in patients with acute lung injury without haemodynamic instability 6.

Outcomes and Risks of AKI

• Even one episode of AKI increases the risk of cardiovascular disease, chronic kidney disease, and death 2.
• The course of AKI can be variable, from single hit and complete recovery, to multiple hits resulting in end-stage renal disease 3.
• Awareness campaigns and education for health-care professionals on diagnosis and management of AKI can improve outcomes 3.