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Test Code BUN BUN

Clinical System Name



Blood Urea Nitrogen


A high serum urea nitrogen occurs in glomerulonephritis, shock, urinary tract obstruction, pyelonephritis, severe congestive heart failure, hyperalimentation, diabetic ketoacidosis, dehydration, bleeding from the gastrointestinal tract, and other causes of acute and chronic renal failure. Low urea nitrogen often occurs in normal pregnancy, with decreased protein intake, in acute liver failure, and with intravenous fluid administration.

Sample Requirements

Specimen: Whole Blood

Container(s): Gold SST, Dark Green/Sodium Heparin, Red, Gold Microtainer, Lt. Green/Li Heparin Microtainer

Preferred Vol: 1 mL

Minimum Vol: 0.5 mL


Note: Method is affected by hemolysis. Not affected by icterus, lipemia or heparin.


Processing Instructions

Reject due to: Hemolysis, age of specimen

Spin: Y

Aliquot: Y

Temp: 2-8oC

Storage location: Core 5 Chemistry Refrigerator


Off-site collection: Avoid hemolysis. Spin blood, refrigerate serum or plasma at 2-8oC.



Specimen Type Temperature Time
Serum or Plasma RT

24 H

Serum or Plasma 2-8oC

 5 D

Serum or Plasma -20oC or -70oC

180 D



STAT Performed TAT
Y 24/7 1 H


Performing Laboratory

Seattle Children's Laboratory    


Department:  Core Chemistry

Phone Number: 206-987-2617

Reference Range

All Ages: 6 - 20 mg/dL


Method: Colorimetric by Vitros 4600

Analytical Volume: 0.02 mL + 0.03 mL dead space



CPT Codes


Critical Values

≥ 100 mg/dL