Blood Urea Nitrogen (BUN)

Nitrogen waste from protein breakdown. BUN/creatinine ratio helps differentiate causes of kidney injury.

Units

mg/dL

Reference (Male)

7 – 20 mg/dL

Reference (Female)

7 – 20 mg/dL

Aliases

Urea

What it measures

Nitrogen waste from protein breakdown. BUN/creatinine ratio helps differentiate causes of kidney injury.

What a high value can mean

Dehydration, kidney disease, GI bleeding, high-protein diet, heart failure.

What a low value can mean

Liver disease, low-protein diet, overhydration, pregnancy.

Conditions it helps assess

Kidney function
Protein metabolism

Reading these numbers in context

Reference ranges describe the central 95 % of a healthy reference population — 5 % of perfectly healthy people fall outside any given range by definition. A single mildly abnormal value is rarely meaningful on its own. blood-test.life always interprets values together with related biomarkers before flagging.

Related biomarkers in Kidney Panel

Creatinine CR Waste product of muscle metabolism, cleared by kidneys. Used to estimate eGFR. Estimated GFR eGFR Calculated kidney filtration rate. Defines chronic kidney disease (CKD) stage.