• Assay Type Detection Kit
  • Sample Types Serum, Plasma, Urine, Saliva
  • Sensitivity 30 µg/dL
  • Species Species Independent
  • Assay Duration 30 Minutes
  • Samples/Plate 40 in Duplicate
  • Readout Colorimetric, 450 nm
  • Standard Curve
  • Description

    Assay Principle: 

    The Urea Nitrogen (BUN) Colorimetric Detection Kit quantitatively measures urea nitrogen levels in serum, plasma, urine, and saliva. The Urea Nitrogen (BUN) Colorimetric Detection Kit is a Detection Kit with a run time of 30 minutes. Please read the complete kit insert for more information before performing this assay.

    Use our provided Urea Nitrogen standard to generate a standard curve for the assay. Pipette the standards or diluted samples into a transparent microtiter plate. Add color reagents A and B to each well, tapping the plate to ensure sufficient mixing of reagents. Then, incubate the mixture at room temperature for 30 minutes. The color-generating reaction occurs between the color reagents and the Urea Nitrogen within the sample or standard. 

    After the 30-minute incubation with the color reagents, use a plate reader to detect and record the generated signal at 450nm. Use the intensity and the standard curve to calculate the Urea Nitrogen concentration in the samples.


    The liver generates Urea as a by-product of protein metabolism, which is later filtered from the blood by the kidneys. Urea freely filters through the glomerulus but is reabsorbed by the renal tubules in a flow-dependent fashion. A higher flow rate causes more urea nitrogen clearance from the circulation and elimination through the kidneys. As a result, the level of circulating urea nitrogen and serum creatinine serves as a primary measure of kidney function.

    Average adult blood urea nitrogen (BUN) levels should be between 7 and 21 mg urea nitrogen per 100 mL blood (mg/dL). Azotemia, poor kidney function, will cause elevated BUN levels (≥ 50 mg/dL) and is associated with acute kidney failure or injury, severe acute pancreatitis, congestive heart failure, or gastrointestinal bleeding. Azotemia also can occur with dehydration, as a result of alcohol abuse, or with high protein diets. Lower than expected BUN levels are usually not clinically predictive but are primarily associated with liver disease or malnutrition, including malabsorption and low protein diets. Urine and saliva are acceptable non-invasive samples for the measurement of urea nitrogen.