Blood Urea Nitrogen (BUN): Low and High BUN Ranges

Blood Urea Nitrogen (BUN): Low and High Ranges

July 22, 2019

Blood urea nitrogen test is one of the many tests requested for in the hospital. This test helps a doctor check for abnormalities with organs in the body. Especially problems that have to do with the liver and also the kidney. Blood urea nitrogen test basically measures the amount of urea nitrogen in the blood. The result could be either high, low or normal. This is referred to as BUN ranges. It’s important to understand BUN ranges so that you will have an idea of what your test result implies.

Most people assume that the BUN test is basically for checking kidney function. Well, this is true. But there is more than the result of your BUN test can indicate. Abnormal results could be either low or high. And both low and high are indicative of different health conditions. We will have a look at the health conditions as we go on. At the same time, it could just be as a result of diet changes. Also, we will have a look at how the test is done and how you can interpret your test result.


How Does Your Body Form Urea

Understanding how urea is formed in your body is important. This is because a good understanding of how urea is formed would help you understand where the problem could probably lie.

Amino acids that are not used for the production of protein and other biological substances are oxidized by the body. When oxidation occurs urea and carbon dioxide are formed.

The first step involves the formation of ammonia by the liver. This step using amino acids from protein. And converting it to metabolic waste. Ammonia is toxic so it is immediately converted to urea in our body.

Urea is then dissolved in our blood. After that, it is transported by the kidney. The kidney excretes urea as a component of urine. Also, urine is also excreted in sweat. It accompanies sodium chloride and water when we sweat.

So kidneys play a vital role in the excretion of urea from the body. This is why a high amount of BUN level could be indicative of a problem with the kidney.


Why You Should Do the Test

There are times that your doctor would order for a BUN test as part of your routine checkup. But most times a BUN test is ordered when there’s a suspected problem with your kidneys. Also, for some other medical conditions BUN test would be required for diagnosis.

These are some of the symptoms that might indicate that you have a problem with your kidneys.

  1. Sudden change in the amount of urine you void in a day
  2. Pain in the middle portion of your back
  3. Joint pain
  4. Painful urination
  5. Unexplainable tiredness
  6. Swelling of your arms, legs, abdomen, and face
  7. Dark-colored and foamy urine

A BUN test is often done along with many other tests. One common test usually done along with a BUN test is a creatinine test. BUN creatinine ratio is used to check for problems with the kidney.

Also, when your doctor suspects other conditions BUN test can be requested. Such conditions are liver damage, malnutrition, dehydration, congestive heart failure, and urinary tract obstruction. One other thing BUN test can be used for is to check for the effectiveness of dialysis.

Another reason BUN test is done is if you are at high risk of having a kidney disease. When kidney disease is an early stage it doesn’t show symptoms. Here are some things that can put you at higher risks:

  1. A family history of kidney problem
  2. Heart disease
  3. Diabetes
  4. Hypertension

With any of these risk factors, there are higher chances that you could have a kidney problem. So to be on the safe side your doctor would request for a BUN test. If it turns out you have kidney failure and it’s still at an early stage then medical intervention is needed. But the good thing is that severe damage isn’t done to the kidneys before you found out.


Interpreting BUN Range

The normal range of BUN level is 7-20 mg/dl. If your test result is higher or lower than this BUN range then there could be an underlying problem. There are times though that an abnormal BUN level isn’t as a result of any serious health condition.

Here are some of the things that could affect your BUN levels.

  1. Aging
  2. Pregnancy
  3. High protein diet: A high protein diet can lead to elevated BUN levels. Because there is an increased amount of ammonia being converted to urea.
  4. Low protein diet: It can cause a low BUN level. When there’s a decrease in the amount of protein that is being consumed the urea that would be produced will also decrease.
  5. Medications: This can lead to either a decrease or an increase. These medications include steroids and also antibiotics.


Causes of High BUN Level

Elevated BUN level can be as a result of problems with the kidney. In actual fact, this is the most common cause. There are also other conditions that can elevate BUN levels.

  1. Congestive heart failure
  2. Dehydration
  3. Burn injuries
  4. Shock
  5. Urinary tract obstruction
  6. Heart attack
  7. Stress
  8. Gastrointestinal bleeding

Low levels of BUN are not so common. It could be indicative of a few conditions.

  1. Malnutrition
  2. Overhydration
  3. Liver disease

As you can see from the causes stated above BUN test has its own limitations. Sudden large change in BUN levels can be affected by a lot of things. Which include diet, hydration, and even medications. That’s why doctors cannot just conclude from BUN test result that a patient has a serious medical condition. This is why other tests are important.

So BUN test is not a definite diagnostic tool for any disease or condition. It just helps confirm alongside many other tests if a patient really has a serious medical condition. Even though all the accolades can’t be given to BUN test in terms of diagnosis it sure helps out a long way. BUN ranges are sure one helping tool doctors have.