BUN
Blood urea nitrogen
High
21.8mg·dL⁻¹Ref 7–20 mg·dL⁻¹
Z +2.55↑ Bad

The card shows an example result of 21.8 mg·dL⁻¹, which is 2.55 SD above the mean.

What it measures

Blood urea nitrogen comes from protein broken down in the liver and is cleared by the kidneys.

Reference range

FieldValue
AbbreviationBUN
GroupKidney and protein
Unitmg·dL⁻¹
Healthy range7–20
Mean13.5
SD3.25
Direction↑ Bad — a raised value is the concern.

The mean is (low + high) / 2 and the SD is (high − low) / 4, so the healthy range covers Z from −2 to +2.

Reading the result

  • High — Can mean reduced kidney function, dehydration, a high-protein diet, or bleeding in the gut.
  • Low — Not the concern this panel tracks. Low values can come from a low-protein diet or liver disease.

Notes

  • The BUN-to-creatinine ratio helps tell kidney causes from others.
  • This page is general information, not medical advice. Discuss results with a clinician.