Urea Nitrogen (BUN)

Serum urea nitrogen (BUN) is increased in acute and chronic intrinsic renal disease, in states characterized by decreased effective circulating blood volume with decreased renal perfusion, in postrenal obstruction of urine flow, and in high protein intake states.

Decreased serum urea nitrogen (BUN) is seen in high carbohydrate/low protein diets, states characterized by increased anabolic demand (late pregnancy, infancy, acromegaly), malabsorption states, and severe liver damage.

In Europe, the test is called simply “urea.”

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