Therefore, an elevated BUN by itself may not be clinically meaningful. As mentioned above, mild elevations on a scale of 10 to 20 units can be normal for your dog if other testing of kidney function is also normal. With kidney disease, the BUN begins to slowly elevate. Unfortunately, it’s also affected by other factors such as intestinal bleeding and dietary protein levels. Kidney function BUNīUN is a common test of kidney function. Let’s take a look at some commonly performed tests and what they mean. However, re-do the test every few months, especially if you have an older dog since kidney disease is more common in senior animals. If they weren’t, it’s likely your dog’s BUN value of 40 is nothing to worry about. Look at other tests of kidney function (creatinine, phosphorus, complete urinalysis, etc.) and see if those were abnormal. If he has never had this test done before, repeat it in one to two weeks and compare the value to the current one. If your dog has always had BUN values close to 40, it’s probably safe to say this is another normal test. How do you determine if this is normal, or a sign of potentially serious kidney disease? This is where the vet’s medical training and experience comes in to determine if it was normal for your dog (in which case it’s nothing to worry about) or abnormal.įirst, look at BUN values from prior tests, if available. Let’s suppose your dog has a BUN value of 40, which is outside the normal range on the high end.

However, 5% of normal dogs will have a lab value less than 10 and 5% a value greater than 30. This means 90% of normal dogs will have a BUN value anywhere from 10 to 30. Normal values for most labs are 10 to 30. A low BUN-to-creatinine ratio may be caused by a diet low in protein, a severe muscle injury called rhabdomyolysis, pregnancy, cirrhosis, or syndrome of inappropriate antidiuretic hormone secretion (SIADH).As an example, let’s look at the BUN test (blood urea nitrogen), commonly used to determine kidney disease.Women and children may have lower BUN levels than men because of how their bodies break down protein.Drinking too much liquid may cause overhydration and cause a low BUN value.A low BUN value may be caused by a diet very low in protein, by malnutrition, or by severe liver damage.A very high BUN-to-creatinine ratio may be caused by bleeding in the digestive tract or respiratory tract. High BUN-to-creatinine ratios occur with sudden (acute) kidney problems, which may be caused by shock or severe dehydration.A high BUN value may be caused by a high-protein diet, Addison's disease, or tissue damage (such as from severe burns), or from bleeding in the gastrointestinal tract.Be sure to tell your doctor about all the non-prescription and prescription medicines you take. High BUN levels can also be caused by low blood flow to the kidneys caused by dehydration or heart failure. Kidney damage can be caused by diabetes or high blood pressure that directly affects the kidneys. A high BUN value can mean kidney injury or disease is present.A value that isn't in the normal range may still be normal for you. Your doctor will also look at your results based on your age, health, and other factors. Your lab report should show the range that your lab uses for each test. A BUN-to-creatinine ratio can help your doctor check for problems, such as dehydration, that may cause abnormal BUN and creatinine levels.Įach lab has a different range for what's normal. Blood urea nitrogen (BUN) and creatinine tests can be used together to find the BUN-to-creatinine ratio (BUN:creatinine). The level of creatinine in your blood also tells how well your kidneys are working-a high creatinine level may mean your kidneys are not working properly. Blood urea nitrogen to creatinine ratio (BUN:creatinine)Ī BUN test may be done with a blood creatinine test. A low BUN level can occur normally in the second or third trimester of pregnancy. Liver disease or damage can lower your BUN level. Heart failure, dehydration, or a diet high in protein can also make your BUN level higher. If your kidneys are not able to remove urea from the blood normally, your BUN level rises. Urea is made in the liver and passed out of your body in the urine.Ī BUN test is done to see how well your kidneys are working. Urea is made when protein is broken down in your body. A blood urea nitrogen (BUN) test measures the amount of nitrogen in your blood that comes from the waste product urea.

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