Blood Urea Nitrogen BUN
Also known as
BUN, Urea Nitrogen, BUN to Creatinine Ratio
The test is ordered by the doctor when he or she wants to assess the health of the patient’s kidneys and diagnose kidney disease. The test results are also used to evaluate whether the treatment plan for diagnosed kidney disorders, damage, or disease is progressing well and whether dialysis is effective or not.
The test can be ordered as part of a routine health exam – in this case, a comprehensive or basic metabolic panel is ordered. The doctor also orders it when the patient has signs and symptoms linked to kidneys disease or when the patient already has a condition that can be further aggravated by kidney dysfunction. It is also ordered are regular intervals when the patient is being treated for kidney disease or damage.
This is a blood test. The technician draws a sample of blood from a vein in the arm using a syringe.
There is no preparation needed for the test.
This test measures the components of blood, urea, nitrogen in the blood. Urea is a waste product that is formed in the liver when protein is broken down into amino acids. In this process, ammonia is made as a by-product, which is then converted into a less toxic form of urea. In some cases, the BUN to creatinine ratio is ordered to identify why the levels are elevated in the blood. Nitrogen is found in both ammonia and urea both. Urea and urea nitrogen can be referred to as one another interchangeable, as urea contains nitrogen, and urea nitrogen is the way excess nitrogen is eliminated from the body.
Urea is made in the liver and released into the blood. From here on, it is carried into the kidneys, where it is filtered out of the blood and released into the urine. This process is always going on in the body. Therefore, there are small yet stable amounts of urea nitrogen to be found in the blood always. However, when the kidney malfunctions, it can not filter waste out of the body as effectively, which leads to elevated levels of urea in the blood. The kidneys are a small pair of bean-shaped organs that are found at the bottom of the ribcage. Structurally, they host blood-filtering units called nephrons, which filter blood via the glomerulus. The glomerulus permits the flow of water and small molecules but retains blood cells and larger molecules.
The tubules in the glomerulus reabsorb what can be used by the body, and the remaining waste is expelled from the body in the form of urine. The disease of the kidney often impacts the amount of urea found in the blood. Difficulty in filtering waste can cause the levels of urea to rise, while disorders which inhibit the production of urea cause BUN levels to fall.
The test is used in conjunction with a creatinine test in order to evaluate how the kidney is functioning in different circumstances, to help in the diagnosis of kidney disease, and to monitor people that have kidney disease or failure. It is also useful in evaluating the general health status of individuals as part of a renal panel, basic metabolic panel or comprehensive metabolic panel. If the levels are not normal, or the patient has a known underlying disease that impacts kidneys, then the results are used to evaluate if the treatment is effective or not. Furthermore, the test may also be used to assess kidney function before some procedures like CT.
The test is ordered when it is suspected that the patient has kidney problems. The signs and symptoms are:
- Blood and/or protein in your urine
- Swelling or puffiness (oedema), particularly around the eyes or in the face, wrists, abdomen, thighs, or ankles
- Urine that is foamy, bloody, or dark in color
- A marked decrease in the amount of urine
- Problems urinating, such as a burning feeling or abnormal discharge during urination, or a change in the frequency of urination, especially at night
- Mid-back pain (flank), below the ribs, near where the kidneys are located
- High blood pressure (hypertension)
In general, normal ranges of BUN vary. If test results indicate high levels of BUN, it is assigned that the kidneys are not working properly. But abnormal test results are not specific, as they don’t always imply that the patient has a condition that warrants treatment. Higher levels of BUN can also be caused by things like dehydration, burns, some medicines, high protein diets, and other factors. BUN levels tend to increase with age. However, there are some known conditions that can increase BUN levels. These include:
- Kidney disease, kidney damage, or kidney failure
- Decreased blood flow to the kidneys, caused by conditions such as congestive heart failure, shock, stress, recent heart attack, or severe burns
- Conditions that can block the flow of urine, such as kidney stones
Related Tests Creatinine serum, Creatinine Clearance, Estimated Glomerular Filtration Rate (eGFR), Comprehensive Metabolic Panel (CMP blood test), Basic Metabolic Panel (BMP), urinalysis complete, Cystatin C, Urine Albumin and Albumin to Creatinine Ratio, Renal Panel, Beta-2 Microglobulin, Kidney Disease, Urine Protein and Urine Protein to Creatinine Ratio,
Frequently ordered together
Microalbumin 24 Hour Urine
Basic Metabolic Panel BMP
Comprehensive Metabolic Panel CMP
Creatinine Serum
Creatinine Urine
Microalbumin Urine
Renal Function Test
Urine Analysis Complete
Ultrasound Kidney
Ultrasound Kidney Ureter Bladder
Protein Total and Albumin-Plasma
Glomerular Basement Membrane GBM Antibody
BETA-2-MICROGLOBULIN
Blood Urea Nitrogen BUN-Creatinine Ratio
Kidney Profile
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See Physicians Online
Conditions Treated
- Hypertension
- Acid Base Disorders
- Hematuria (Blood in urine)
- Proteinuria (Protein in urine)
- Acute Kidney Failure
- Chronic Kidney Diseases (CKD) including diabetes related CKD
- End stage renal disease needing dialysis or Kidney Transplant
- Kidney Stones
Hasan Riaz MD
Conditions Treated
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- Valvular Heart Diseases (aortic valve stenosis, mitral valve regurgitation etc)
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- General and Urgent Care- all ages
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- Abdominal Pain and Pelvic Floor Disorders
- Achalasia
- Anorectal Diseases
- Barrett's Esophagus
- Biliary and Pancreatic Disorders
- Esophageal Disorders
- Gastroesophageal Reflux Disease or GERD
- Gastrointestinal Malignancies
- High Grade Dysplasia
- Inflammatory Bowel Disease, Crohn's Disease, and Ulcerative Colitis
- Liver Disease
- Motility Disorders
- Zenker's Diverticulum
- Interventional gastroenterology procedures like Endoscopic ultrasound, ERCP, Barrett’s treatment. liver and lymph node biopsies etc
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Conditions Treated
- Acute And Chronic Conditions
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