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Prerenal acute kidney injury—still a relevant term in modern clinical practice?

The traditional, ‘anatomic flow’ model classifies AKI as either prerenal, intrinsic renal or postrenal, and evidence suggests that clinicians treat patients according to this established conceptual framework. There is no consensus definition of prerenal AKI. The condition is generally understood to represent transient kidney dysfunction, as assessed by SCr, which reverts to normal within 24–72 h of the triggering insult. The lack of a widely accepted definition makes it difficult to ascertain its true incidence, natural history and morbidity. Due to its association with inadequate renal perfusion, the term is often used synonymously with hypoperfusion-associated azotemia. By extension, the…

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 Low-Flow Acute Kidney Injury

Prerenal azotemia, also known as functional AKI, results from many different pathophysiologic processes and is the most common cause of AKI, accounting for up to 50% of all AKI cases. Prerenal azotemia is diagnosed by an elevation of serum creatinine or low urine flow rate without positive urinary cell injury biomarkers.

Articles of Interest

Urinalysis and pre-renal acute kidney injury: time to move on

Urinary indices are classically believed to allow differentiation of transient (or pre-renal) acute kidney injury (AKI) from persistent (or acute tubular necrosis) AKI. However, the data validating urinalysis in critically ill patients are weak.

Acute Kidney Injury – A Simple Emergency Approach to AKI

Prerenal AKI, caused by decreased renal perfusion, is the most common cause of all AKIs (90%). Prerenal causes occur in the setting of recent volume losses, such as hemorrhage, gastrointestinal or urinary fluid losses, sepsis, and recent postoperative courses during which the patient was hypotensive. Additional pre-renal causes of AKI to consider include: Hepatorenal syndrome, Abdominal compartment syndrome, Hypertensive emergency, Thrombotic thrombocytopenic purpura & hemolytic uremic syndrome.

Identification of Pre-Renal and Intrinsic Acute Kidney Injury by Anamnestic and Biochemical Criteria: Distinct Association with Urinary Injury Biomarkers

Distinction of AKI types may be, in practice, a complicated task. The gold standard diagnostic biomarker (i.e., plasma creatinine concentration, Crp) provides no etiological information, as it increases in all forms of AKI. Indeed, undamaged renal parenchyma may be found with all levels of Crp, and Crp may be found to be normal through a range of parenchymal damage.

Kidney Boy on Acute Kidney Injury: Myths & Musings

Pre-Renal: Inadequate renal perfusion due to volume deficiency (vomiting, diarrhea, decreased PO intake, bleeding, non-hemorrhagic shock) or heart-failure (volume overload with venous congestion resulting in poor renal perfusion).

Overview Of Prerenal Pathology

Intravascular volume depletion, as well as insufficient fluid supply, are the most common causes of pre-renal failure. A lack of oral intake or excessive fluid loss can result in increased internal volume depletion.

Resources

StatPearls

Prerenal AKI is an extensively researched topic, which requires prompt identification and early intervention to prevent long term sequelae.