BUN AND CREATININE LEVELS NORMAL RANGE MANUAL

There is no definite value of BUN that would diagnose kidney failure. A decline in kidney function can cause an increase in BUN levels. There may be slight variations between labs. The normal range of blood urea nitrogen (BUN) is between 7 and 20 mg/dL or 2.5 and 7.1 mmol/L.

BUN AND CREATININE LEVELS NORMAL RANGE MANUAL

For the adult male, the normal range is 0.6 to 1.2 mg/dl, or 53 to 106 μmol/L by the kinetic or enzymatic method, and 0.8 to 1.5 mg/dl, or 70 to 133 μmol/L by the older manual Jaffé reaction. There is no definite value of BUN that would diagnose kidney failure. The normal serum creatinine ( sCr) varies with the subject's body muscle mass and with the technique used to measure it. In contrast, the rugged rancher who eats in excess of 125 g protein each day may have a normal BUN of 20 mg/dl. Her higher glomerular filtration rate (GFR), expanded extracellular fluid volume, and anabolism in the developing fetus contribute to her relatively low BUN of 5 to 7 mg/dl. A BUN of 15 mg/dl would represent significantly impaired function for a woman in the thirtieth week of gestation. The range is wide because of normal variations due to protein intake, endogenous protein catabolism, state of hydration, hepatic urea synthesis, and renal urea excretion. The normal range of urea nitrogen in blood or serum is 5 to 20 mg/dl, or 1.8 to 7.1 mmol urea per liter. The BUN, then, is roughly one-half (28/60 or 0.446) of the blood urea. In Europe, the whole urea molecule is assayed, whereas in the United States only the nitrogen component of urea (the blood or serum urea nitrogen, i.e., BUN or SUN) is measured. Both are relatively small molecules (60 and 113 daltons, respectively) that distribute throughout total body water. Creatinine is the product of muscle creatine catabolism. Urea is the primary metabolite derived from dietary protein and tissue protein turnover. Urea and creatinine are nitrogenous end products of metabolism.

Bun and creatinine levels normal range