Urea nitrogen is a product of protein breakdown. The blood urea nitrogen (BUN) assay is a method for measuring urea nitrogen levels in standardized blood samples. According to the American Association for Clinical Chemistry (AACC), the BUN assay is primarily used to assess kidney health. Recently, Dr. Jennifer Huizen published an article on the MNT website detailing the reasons, timing, precautions, and interpretation of the results of BUN assays, organized as follows: Reasons and Timing of BUN Assays There are various reasons why healthcare professionals perform BUN assays, mainly to check or monitor kidney and liver function. Because urea nitrogen is a breakdown product of protein, blood urea nitrogen levels are highly susceptible to liver and kidney effects. Urea is released into the blood by the liver, filtered by the kidneys and excreted through the urine. Nitrogen, however, is present in urea and helps to remove more than the nitrogen from the body. Therefore, “urea” and “urea nitrogen” usually refer to the same thing. Patients suspected of having kidney or liver disease often need to have their BUN measured. According to the Centers for Disease Control and Prevention (CDC), 10 percent of adults in the United States have long-term kidney disease. And most people are not aware of it. Symptoms of kidney disease 1. frequent urination, especially at night 2. change in urine volume 3. burning sensation in the urethra during urination 4. foamy, coffee-colored, or hematuria 5. diarrhea 6. joint or bone pain, especially around the kidneys 7. muscle cramps 8. hyperactive legs during sleep 9. interrupted sleep 10. fatigue 11. difficulty concentrating 12. itching 13. loss of appetite 14. swelling or puffiness, especially in the face, wrists, ankles 15, hypertension Symptoms of liver disease 1, dark urine 2, pale face, blood in stools, or tarry stools 3, yellowish staining of skin or sclera 4, easy bruising 5, loss of appetite 6, nausea or vomiting 7, weight loss 8, fatigue or weakness 9, stomach pain and swelling 10, swollen legs and ankles 11, itching Precautions before BUN measurement National Institute of Diabetes and Digestive and Kidney Diseases explains that most medications can affect BUN levels and kidney function. Over-the-counter painkillers, especially NSAIDS, can affect kidney function, such as ibuprofen, naproxen and aspirin. Natural diuretics, such as caffeine and steroids, can also affect kidney function. Antibiotics can also affect BUN levels. Prescription drugs that can affect the kidneys causing abnormal BUN levels are: 1. Amphotericin B 2. Carbamazepine 3. Celecoxib 4. Cephalosporin 5. Tachyphylaxis 6. Methotrexate 7. Methyldopa 8. Penicillin 9. Rifampin 10. Ampicillin 11. Sulfonamides 12. Tetracycline 13. Thiazide diuretics 14. Vancomycin The National Kidney Foundation believes that dietary supplements can also have a negatively, leading to abnormal BUN levels. In general, natural health products are not regulated by the FDA. This means that there is no strong evidence on the effective dose, source, and precise mix of dietary supplements. It also means that herbal supplements may contain nephrotoxic ingredients, such as heavy metals or chemicals similar to aristolochic acid. Patients with kidney disease are generally advised to avoid natural supplements and to control phosphorus and potassium intake. Interpretation of BUN measurements Normal blood urea nitrogen levels are 7-22 mg/dl. Blood urea nitrogen > 50 mg/dl indicates the presence of a possible disease. The causes of elevated BUN level are: 1, kidney injury, kidney failure or kidney disease 2, dehydration 3, shock 4, urinary tract obstruction or disease 5, gastrointestinal tract disease or bleeding 6, heart disease 7, heart failure 8, excessive protein intake 9, poor circulation 10, obesity 11, hypercholesterolemia The causes of decreased BUN level are: 1, liver failure 2, water toxicity 3, insufficient protein intake 4, poor nutrition Malnutrition BUN level is also affected by age, gender, and pregnancy. Usually, BUN level increases with age. BUN levels by age and gender Children: 5-18 mg/dl Adult men: 8-20 mg/dl Adult women: 6-20 mg/dl BUN measurement also helps to determine the efficacy of renal treatments such as dialysis. Follow-up treatment and testing BUN measurements alone are not sufficient to confirm any diagnosis of disease. If the BUN result is abnormal, the clinician usually needs to perform additional tests. Creatinine tests and kidney tests can help diagnose kidney and liver disease. Potassium, sodium and calcium levels may also be tested, as well as urine tests. In some cases, a blood urea nitrogen/creatinine ratio may also be performed. The normal value is 10:1-20:1. Treatment of patients with abnormal BUN levels varies depending on the cause and severity of the disease. Patients with organ failure usually require intensive therapy and dialysis, while those with small changes in BUN levels may only require long-term monitoring. Those with abnormal BUN levels due to excessive protein intake may limit the intake of protein-rich foods such as meat, fish, legumes and dairy products, and increase the intake of fruits and vegetables. Maintaining hydration status can also help prevent an increase in BUN. BUN levels are also associated with hypertension and diabetes. Since stress has a greater impact on blood pressure, exercising and relieving stress may help stabilize BUN levels. Controlling blood sugar levels can also help maintain normal BUN levels.