Blood Urea Nitrogen (BUN)
CPT Code(s):
84520
Turnaround Time:
8 hours
Specimen Requirements
Preferred Specimen:
Serum
Minimum Volume:
1.0 mL
Transport Container:
Serum Separator Tube (SST)
Transport Temperature:
Room Temperature
Collection Instructions:
Allow blood to clot completely prior to centrifugation. Separate serum from cells within 45 minutes of collection.
Rejection Criteria:
Citrate, Fluoride,Sodium Heparin, or EDTA plasma specimen; gross hemolysis; lipemia; improper labeling
Stability Criteria
Room Temperature:
5 days
Refrigerated:
7 days
Frozen:
30 days
Clinical Significance
The Blood Urea Nitrogen (BUN) test holds specific clinical significance and diagnostic use in the field of clinical chemistry and nephrology. This test measures the level of urea nitrogen in a patient's blood, providing valuable information about kidney function and overall health.
The clinical significance and diagnostic use of Blood Urea Nitrogen include:
1. Evaluation of Kidney Function: BUN is commonly used as a marker of kidney function. Urea is a waste product produced during the breakdown of proteins in the body, and it is primarily eliminated through the kidneys. Elevated BUN levels can indicate impaired kidney function or acute kidney injury. BUN helps identify kidney dysfunction and provides baseline values for monitoring kidney health and assessing the effects of medications or treatments on renal function.
2. Assessment of Dehydration: In cases of dehydration, BUN can be used to assess fluid balance. When the body is dehydrated, there is less fluid available for excretion, leading to an increase in urea nitrogen concentration in the blood. Elevated BUN levels, along with other clinical and laboratory findings, can suggest dehydration and aid in determining appropriate fluid replacement strategies.
3. Monitoring Kidney Diseases: BUN is valuable in monitoring the progression and treatment response of kidney diseases. Serial measurements of BUN levels can help assess the severity of kidney dysfunction, track disease progression, and monitor the effectiveness of interventions or medications aimed at improving renal function.
4. Assessment of Protein Intake and Digestion: BUN can provide insight into protein intake and digestion. Urea nitrogen is a byproduct of protein metabolism, and increased BUN levels may be observed in individuals with high protein diets or certain gastrointestinal disorders affecting protein digestion.
5. Assessment of Bleeding in the Digestive Tract: In some cases, bleeding in the upper digestive tract can lead to elevated BUN levels. The breakdown of blood proteins in the gastrointestinal tract results in increased urea production and subsequent elevation of BUN levels. BUN can assist in the evaluation of gastrointestinal bleeding when considered alongside other clinical findings.
In summary, Blood Urea Nitrogen has specific clinical significance in assessing kidney function, evaluating hydration status, monitoring kidney diseases, assessing protein intake and digestion, and aiding in the evaluation of gastrointestinal bleeding. By measuring BUN levels, healthcare providers gain valuable insights into renal function and overall health, assisting in the diagnosis, management, and monitoring of various conditions, and guiding appropriate treatment decisions.