What can a BUN test tell you?
The BUN test helps assess how efficiently your kidneys remove waste and can also provide clues about your hydration status, protein metabolism, and liver function. When interpreted with creatinine and the BUN-to-creatinine ratio, it helps identify whether kidney dysfunction is due to dehydration, intrinsic kidney disease, or obstruction.
What is being tested?
The BUN test measures urea nitrogen, a byproduct of protein metabolism. Your body breaks down dietary proteins into amino acids, which produces ammonia. Your liver then converts ammonia to urea, a less toxic compound, and your kidneys filter urea from your blood so it can be excreted through your urine.
If the kidneys are under-functioning or blood flow to them is reduced, urea builds up in the blood, raising BUN levels. Conversely, if liver function is compromised, urea production declines, lowering BUN.
Because diet, hydration, and liver function influence BUN, providers interpret it alongside serum creatinine and the BUN/creatinine ratio for a fuller assessment of kidney function.
Where is the BUN test typically included?
The BUN test is a standard part of basic and comprehensive metabolic panels (BMP and CMP).
Rarely, BUN may also be ordered separately to monitor known kidney conditions, hydration levels, or response to treatment.
BUN testing is included as part of lab testing through Hers, which goes beyond standard lab tests to help you understand what’s really going on in your body and either address or get ahead of problem areas with a tailored action plan.
Who should get a BUN test?
Providers may order a BUN test if you have potential symptoms of kidney dysfunction, such as fatigue, swelling in the legs or ankles, or changes in urine output.
You may also need this test if you take certain medications that affect the kidneys or you’re at higher risk for kidney disease, especially if you have diabetes, high blood pressure, heart disease, or a family history of kidney issues.
