Treatment of Significantly Elevated Blood Urea Nitrogen (BUN)

Diagnostic Approach

The American Heart Association recommends evaluating volume status and cardiac function first, as prerenal causes are most common and potentially reversible, looking for signs of dehydration or heart failure 1, 2.

The American College of Cardiology suggests restoring intravascular volume with intravenous fluids if the patient is dehydrated, as this is the most common reversible cause of elevated BUN 2.
The American Heart Association recommends monitoring for progressive deterioration in renal function, as this indicates advanced heart failure and portends poor prognosis 1.

The American College of Cardiology recommends that if on ACE inhibitors or ARBs with rising BUN, an interruption or reduction in dosage may be necessary if BUN rises excessively (>50% above baseline) or if accompanied by significant creatinine elevation 2.

The National Kidney Foundation suggests monitoring for signs of uremia if BUN continues to rise despite treatment, which may indicate need for renal replacement therapy 2.

The American College of Physicians recommends not treating elevated BUN in isolation without identifying the underlying cause, as BUN elevation is a marker of disease severity rather than a disease itself 2.
The American Society of Nephrology suggests not assuming elevated BUN always indicates renal failure—prerenal causes and increased protein catabolism are common and potentially reversible 2.
The National Academy of Clinical Biochemistry recommends not overlooking sampling errors that can falsely affect BUN measurement, including dilution with saline, drawing samples after dialysis has started, or laboratory calibration errors 4, 2.