What does the term "elevated BUN" indicate in renal function testing?

Elevated Blood Urea Nitrogen (BUN) levels can indicate possible impaired kidney function because BUN is a waste product formed in the liver from protein metabolism and is normally excreted by the kidneys. When the kidneys are not functioning properly—due to conditions such as acute or chronic kidney disease—there tends to be a backlog of urea in the bloodstream, leading to an increase in BUN levels.

While elevated BUN can also be associated with dehydration, it specifically points to an issue with the kidney's ability to filter and excrete waste products effectively when viewed in the context of renal function. Therefore, focusing on the implications for kidney health makes the understanding of "elevated BUN" especially relevant to monitoring renal function. Conditions that highlight this issue include kidney damage or dysfunction, which is critical when evaluating a patient's renal health.