Adult: 10–20 mg/dL; SI units: 3.6–7.1 mmol/L
Child: 4–16 mg/dL; SI units: 1.4–5.7 mmol/L
Critical Levels:
>40 mg/dL (not dehydrated/no history of renal disease)
>100 mg/dL (patient with history of renal disease)
>20 mg/dL increase in 24 hr (indicates acute renal failure)
. Red-top tube.
■ BUN, a by-product of protein metabolism, is excreted
primarily by the kidneys and therefore reflects kidney
function.
■ Elevated BUN (azotemia) occurs in most renal diseases;
also rises with GI bleeding, dehydration, high protein diet,
and CHF.
