✍️ Written by the MedTestBD Editorial Team · Last reviewed: July 2026
What is the Blood Urea Nitrogen (BUN) Test?
The Blood Urea Nitrogen (BUN) test measures the amount of urea nitrogen in your blood. Urea is a waste product formed in the liver when the body breaks down protein, and it is filtered out of the blood by the kidneys. When the kidneys are not working properly, urea builds up. The BUN test is therefore one of the key indicators of kidney function and is commonly ordered alongside serum creatinine.
Why is the BUN Test Done?
- To assess kidney function and detect chronic kidney disease (CKD)
- To investigate symptoms like swelling, reduced urination, fatigue, or nausea that may suggest kidney problems
- To detect dehydration — BUN rises when the body is under-hydrated even with normal kidneys
- To monitor patients with known kidney disease or those at risk — diabetics, hypertensive patients
- To evaluate liver function indirectly — a very low BUN can suggest liver failure, as the liver produces urea
- Routine part of a kidney function panel or pre-operative workup
Normal BUN Levels
| Group | Normal BUN Range |
|---|---|
| Adults | 7 – 20 mg/dL (2.5 – 7.1 mmol/L) |
| Elderly (over 60) | Slightly higher values are normal |
| Children | 5 – 18 mg/dL |
BUN is most useful when interpreted alongside serum creatinine. The BUN-to-creatinine ratio helps distinguish between kidney disease and dehydration. A high BUN with normal creatinine usually suggests dehydration or a high-protein diet rather than kidney damage.
How to Prepare for the BUN Test
- Fasting for 8 hours may be recommended depending on your doctor's instructions, though it is not always required
- Avoid eating large amounts of red meat or high-protein food the day before the test, as dietary protein raises BUN temporarily
- Drink adequate water unless your doctor has advised fluid restriction
- Inform your doctor about any diuretics, antibiotics, or steroids you are taking
- Avoid heavy exercise before the test
BUN Test Price in Bangladesh
Blood urea nitrogen test prices vary between diagnostic centers across Bangladesh. Compare BUN test prices on MedTestBD →
⚠️ This information is for general reference only. Always consult a qualified physician before undergoing any medical test.
