An isolated elevation in blood urea level is not ‘uraemia’ and not an indication for renal replacement therapy in the ICU

Jack Mackenzie, Bobby Chacko

The decision to initiate renal replacement therapy (RRT) and the optimal timing for commencement is a difficult decision faced by clinicians when treating acute kidney injury (AKI) in the intensive care setting. Without clinically significant ureamic symptoms or emergent indications (electrolyte abnormalities, volume overload) the timing of RRT initiation remains contentious and inconsistent across health providers. Current trends of initiating RRT in the ICU are often based on isolated blood urea levels without clear guidelines demonstrating an upper limit for treatment. Although the appropriate upper limit remains unclear, it is reasonable to conclude that a blood urea level less than 40 mmol/L is not in itself an indication for RRT, especially in the absence of supporting evidence of kidney impairment (anuria, elevated serum creatinine), presenting a welcome reminder to treat the patient and not a number.