Clinical Lab Handbook

Serum and urine are required.

Blood Collection Instructions:

Container/Tube: SST

Alternate Container: Lithium Heparin Gel Tube

Specimen Volume: 5 mL of serum

Collection Instructions: Allow specimen to clot for 30 minutes. Spin specimen in centrifuge.

Urine Collection Instructions

Submit an entire 24-hour urine collection in a urine container. No preservative. Send specimen refrigerated.

1. Starting and ending times of collection are required.
2. Follow instructions in Urine Collections in Special Instructions.

Colorimetric, Urease

The Vitros BUN/UREA slide quantitatively measures urea in serum, plasma, or urine. The major pathway of nitrogen excretion is in the form of urea that is synthesized in the liver, released into the blood, and cleared by the kidneys. Urea excretion is influenced by both glomerular filtration and tubular reabsorption. Although the creatinine clearance test is typically used to measure glomerular function, the urea clearance test can also be used to evaluate glomerular function. Several factors may adversely affect the urea clearance, the main ones being dietary effects on the BUN and the rate of urine flow. Therefore, the urea clearance is a more accurate measure of glomerular filtration rate when reabsorption is lowest (at a high rate of urine flow).

Monday through Sunday

84545-Urea Clearance