A BUN (Blood Urea Nitrogen) test measures the amount of urea nitrogen in the blood, which is a waste product the kidneys filter out. For people with kidney disease, this is an important marker of how well the kidneys are doing their job.
A normal BUN range is typically between 7 and 20 mg/dL. A result of 4 is actually below Show Full Answer
A BUN (Blood Urea Nitrogen) test measures the amount of urea nitrogen in the blood, which is a waste product the kidneys filter out. For people with kidney disease, this is an important marker of how well the kidneys are doing their job.
A normal BUN range is typically between 7 and 20 mg/dL. A result of 4 is actually below the normal range, which can sometimes indicate:
- Very high fluid intake (overhydration)
- Low protein diet
- Liver-related issues affecting urea production
A low BUN on its own isn't always cause for alarm, but it's worth discussing with a nephrologist, especially alongside other kidney function markers like:
- eGFR (how well kidneys filter blood)
- Creatinine (another waste product)
- Urine protein levels
No single number tells the whole story — kidney health is best understood by looking at all results together.
It's really important to bring this result to a nephrologist or doctor who knows the full picture of health history. They can explain what a BUN of 4 means in context and whether any adjustments to diet or treatment are needed.
August 16
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