From the Research
An elevated BUN to creatinine ratio is a strong indicator of prerenal azotemia, often associated with decreased renal perfusion, and is independently associated with higher all-cause mortality in patients with acute decompensated heart failure, as shown in a study published in ESC heart failure 1. This condition can occur due to various factors, including:
- Dehydration
- Volume depletion
- Congestive heart failure
- Shock
- Gastrointestinal bleeding
- High protein diet
- Catabolic states like burns or fever
- Certain medications such as corticosteroids and tetracyclines The BUN to creatinine ratio becomes elevated because urea is reabsorbed in the kidney tubules during states of decreased renal perfusion, while creatinine clearance remains relatively stable. According to a study published in ESC heart failure, a higher BUN/creatinine ratio at discharge was independently associated with higher post-discharge all-cause mortality in patients with ADHF 1. It's essential to interpret the elevated ratio alongside clinical findings and other laboratory values to determine the underlying cause and guide appropriate management strategies. Treatment typically focuses on addressing the underlying cause, often beginning with appropriate fluid resuscitation in cases of dehydration. The ratio is valuable because it helps distinguish between prerenal azotemia (which is often reversible) and intrinsic kidney disease, guiding appropriate management strategies to improve patient outcomes, particularly in terms of morbidity, mortality, and quality of life.