What does a high BUN (blood urea nitrogen) level indicate?

A high blood urea nitrogen (BUN) level primarily indicates the possibility of kidney dysfunction or dehydration. BUN is a waste product formed from the breakdown of proteins and is normally filtered out of the blood by the kidneys. When the kidneys are not functioning properly, they may be unable to eliminate urea effectively, leading to elevated levels in the bloodstream. Additionally, dehydration can concentrate urea in the blood due to reduced blood volume and decreased kidney perfusion, also resulting in higher BUN levels.

In cases of kidney dysfunction, a higher BUN can indicate conditions such as acute kidney injury or chronic kidney disease. Dehydration may also present with high BUN levels, especially when it is severe, affecting the kidneys' ability to filter waste properly.

While elevated BUN can hint at various conditions, its specificity towards kidney function and hydration status makes it a crucial parameter in evaluating renal health and identifying possible underlying issues.