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Low Level Of Blood Urea Nitrogen

What High Bun Levels Can Mean

Introduction to Blood Urea Nitrogen (BUN) Test â Med-Surg | Lecturio Nursing

High BUN levels can also indicate various problems with your kidneys. Talk to your doctor about what could be causing the problem and plan your next steps.

High levels can also indicate the following:

â Dehydration

â Urinary tract obstruction

â Congestive heart failure

â Shock

â Gastrointestinal bleeding

Low BUN levels are rare. If you have low BUN levels, it could indicate:

â Liver disease

â Malnutrition

â Overhydration

But a BUN test is not a way to diagnose these issues, so more tests may be needed

Is There Anything Else I Need To Know About A Bun Test

A BUN test is only one type of measurement of kidney function. If your provider thinks you may have kidney disease, you may need other tests. These may include tests to measure:

  • Creatinine, which is another waste product that your kidneys remove from your body
  • GFR , which estimates how well your kidneys are filtering blood

What Is A Bun Test

A BUN, or blood urea nitrogen test, can provide important information about your kidney function. The main job of your kidneys is to remove waste and extra fluid from your body. If you have kidney disease, this waste material can build up in your blood. Over time, this may lead to serious health problems, including high blood pressure, anemia, and heart disease.

The BUN test measures the amount of urea nitrogen in your blood. Urea nitrogen is a waste product that your kidneys remove from your blood. Higher than normal BUN levels may be a sign that your kidneys aren’t working well.

People with early kidney disease may not have any symptoms. A BUN test can help uncover kidney problems at an early stage when treatment can be more effective.

Other names for a BUN test: Urea nitrogen test, serum BUN

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Why Is A Bun Test Done

A blood urea nitrogen test may be performed as part of your routine checkup. Your doctor may also advise a BUN test if you have any factors that may increase the risk of kidney diseases. The risk factors include:

  • Family history of kidney problems

Blood Urea/blood Urea Nitrogen And Role Of Kidneys And Liver:

Blood Urea Nitrogen, BUN, or Urea Nitrogen (BUN/Creatinine ratio ...
  • The toxic level of NH3 is prevented by converting the NH3 into urea, which will occur in the liver.
  • Urea production and BUN increase when the liver has increased amino acid metabolism.
  • It can occur by increased protein intake, tissue breakdown, or decreased protein synthesis.
  • Urea is decreased in case of severe liver disease and low protein intake.
  • Urea is degraded in the intestine to ammonium ions by the intestinal bacteria.
  • This BUN or urea is excreted through the kidney in the urine.
  • The measurement of urea nitrogen gives an idea of the ratio between excretion and production of urea.
  • Urea is filtered at the glomerulus, and approximately 40% to 50% is reabsorbed in the proximal tubules by passive back-diffusion.
  • In normal conditions, urea clearance values parallel the glomerular filtration rate at about 60% of it.
  • At a low level, when urine output is < 2 mL/minute, the values are very inaccurate, even with the application of correction formulas.
  • In the liver, amino acids are catabolized, and free ammonia is produced.
  • Ammonia molecules combine to form urea.
  • The urea through blood goes to the kidney and is excreted in the urine.
  • So BUN depends upon the livers metabolic function and kidneys excretory function.
  • Urea metabolism and excretion

  • The BUN is directly related to the livers metabolic function and the kidneys excretory function.
  • In chronic renal diseases, the BUN level correlates better than creatinine with the sign and symptoms of the patient.
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    How Do I Prepare For The Test

    Before the blood test, tell your doctor what medications youâre taking. If any of them might alter the test result, your doctor may ask you to stop taking them for a period of time.

    If youâre only getting a BUN test, you can eat and drink. But if youâre getting other blood tests, your doctor may give you directions that may include fasting before the test.

    What Are The Risks Of A Bun Test

    Unless youre seeking care for an emergency medical condition, you can typically return to your normal activities after taking a BUN test. Tell your doctor if you have a bleeding disorder or youre taking certain medications such as blood thinners. This may cause you to bleed more than expected during the test.

    Side effects associated with a BUN test include:

    • bleeding at the puncture site
    • bruising at the puncture site
    • accumulation of blood under the skin
    • infection at the puncture site

    In rare cases, people become lightheaded or faint after having blood drawn. Notify your doctor if you experience any unexpected or prolonged side effects after the test.

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    How Do I Prepare For A Bun Test

    A BUN test doesnt require any special preparation. However, its important to tell your doctor if youre taking any prescription or over-the-counter medications. Certain medications can affect your BUN levels.

    Some medications, including chloramphenicol or streptomycin, may lower your BUN levels. Other drugs, such as certain antibiotics and diuretics, may increase your BUN levels.

    Commonly prescribed medications that may raise your BUN levels include:

    Be sure to tell your doctor if youre taking any of these medications. Your doctor will consider this information when reviewing your test results.

    What Happens During A Blood Urea Nitrogen Test

    Blood Urea Nitrogen (BUN) â Med-Surg | Lecturio Nursing

    The BUN test is a simple blood draw and very little risk is involved. You will sit in a chair and a healthcare professional will insert a thin needle into your arm and draw blood into small vials. You may feel a little prick and the area may bruise slightly afterward. Any marks left by the injection go away quickly. A bandage taped over the spot can be removed a few hours later.

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    High Levels Of Blood Urea Nitrogen

    Several factors can give rise to high levels of blood urea nitrogen, which are levels above the reference value. The most probable factor is kidney damage. Kidney disease or kidney injury can originate from multiple sources such as from high blood pressure and from diabetes. A creatinine blood test in conjunction with a BUN test can help confirm kidney damage.

    Other factors that cause high blood urea nitrogen may involve the respiratory, circulatory and gastrointestinal tracts. For instance, internal bleeding or tissue damage may raise urea nitrogen in the blood. Additional factors include dehydration and a high-protein diet . Some medicines can also instigate high levels of blood urea nitrogen.

    Protein Metabolism And Urea Formation:

  • Proteins cannot be stored in the body. Surplus amino acids are catabolized for energy when these are in excess.
  • Breakdown of the proteins and nucleic acid gives rise to a non-protein nitrogenous compound in the blood:
  • Urea. This is present in high concentrations in the blood. .
  • Amino acids.
  • Ammonia
  • Amino acids are converted into ammonia , CO2, H2O, and energy.
  • NH3, before it reaches a toxic level, is prevented by the conversion of the NH3 to urea.
  • Urea is synthesized in the liver by CO2 and ammonia .
  • CO2 and ammonia are produced from the deamination of the amino acids in the urea cycle.
  • While ammonia forms urea which is excreted into the urine. Conversion of NH3 to urea takes place in the liver.
  • Formation of urea and its clearance

  • Urea is water-soluble and is a waste product excreted in the urine.
  • Urea concentration in the glomerular filtrate is the same as in the plasma.
  • Under normal conditions, 40% of the urea filtered is reabsorbed in the tubules.
  • Urea formation from proteins metabolism

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    What Does A Low Bun Level In The Blood Mean

    Hypoazotemia is not common. It can be a consequence of malnutrition with a low-protein diet and high water intake.

    Hypoazotemia can be a sign of liver disorders, but the BUN it is not used as a diagnose test for the liver because there are other parameters which give better information about liver status.

    BUN values are usually given in mg/dl but sometimes you can see those values in mmol/l following the International System of Units . In case your values are in mmol/l you can convert them using this web

    Warning: In Europe and other countries, the values measured are the total urea instead of BUN . The formula to convert from BUN to urea is BUN= Urea * 0.4667. You can convert them using this tool.

    Urea

    • Mild hypoazotemia :

      Mild hypoazotemia is not usually a matter of concern.

      The main reason is a low-protein diet or over hydration . It is common a low value of BUN in vegetarians due to the low protein intake.

    • Marked hypoazotemia :

      However, when there is a liver disorder, it is better to study other blood test parameters.

    What Does Low Urea Levels Mean For Health

    Blood Urea Nitrogen (BUN)

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    The urea is a colorless, crystalline chemical compound found in the organism of people. It is the main end product of the metabolism of the protein in mammals and is found mainly in the urine, sweat and fecal matter.

    This chemical compound is soluble in water. Thus, the body goes through a process called the urea cycle, by which the body itself transforms nitrogen into urea in order to subsequently expel it through the urine. Therefore, urea is one of the values observed in any blood test.

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    What Are Kidneys And Kidney Function Tests

    Kidneys are vital organs performing various functions such as maintaining fluid and electrolyte balance, controlling blood pressure, removing waste products from the body, maintaining healthy bones and keeping healthy levels of red blood cells in the body. Various tests are performed to know about the health of the kidneys such as:

    • Blood urea

    What Happens During The Test

    A lab tech will take a sample of your blood from a vein in your arm or the back of your hand. You may feel a slight sting when the needle pricks through your skin.

    It may feel a little bit sore afterward, but you can go straight back to your everyday activities.

    Your doctorâs office will send the blood sample to a lab to be analyzed. You should get the results in a few days, depending on how fast the lab and your doctorâs office can work.

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    Why Do I Need A Bun Test

    Your health care provider may order a BUN test as part of a routine check-up or if you have or are at risk for a kidney problem. Early kidney disease usually does not have any signs or symptoms. You may be more likely to develop kidney disease if you have:

    • Family of kidney problems
    • High blood pressure
    • Heart disease

    Your provider may check your BUN levels if you are having symptoms of later stage kidney disease, such as:

    • Needing to urinate more often or less often than usual
    • Itching
    • Swelling in your legs, feet, or ankles
    • Muscle cramps
    • Trouble sleeping

    Why It Is Done

    High Levels of BUN (Blood Urea Nitrogen) on a Ketogenic Diet â Dr.Berg

    A BUN test is done to:

    • See if your kidneys are working normally.
    • See if your kidney disease is getting worse.
    • See if treatment of your kidney disease is working.
    • Check for severe dehydration. Dehydration generally causes BUN levels to rise more than creatinine levels. This causes a high BUN-to-creatinine ratio. Kidney disease or blockage of the flow of urine from your kidney causes both BUN and creatinine levels to go up.

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    What Levels Of Bun Indicates Kidney Failure

    As already mentioned, normal BUN levels vary between 5-20mg/dl. The level in an individual will depend on dietary intake, hydration levels, liver functions, kidney function, medications etc..

    The wide range makes it difficult to point at one specific value that would qualify for kidney failure. To put this into context, for a person who consumes a protein-rich diet, the BUN value of 20mg/dl would be considered normal, However, the same value may be very high for a pregnant woman since her normal levels are between 5-7mg/dl.

    This is why nephrologists often combine BUN with creatinine to estimate the progression of kidney failure.

    Any level that is grossly above normal indicates that significant kidney disease is present. Higher the level, more severe the underlying disease.

    Blood Urea Nitrogen Ranges

    As with multiple clinical assessments, the levels of urea nitrogen in the blood have been well studied and a reference range has been established to determine whether the kidney is healthy or not, i.e. whether the blood urea nitrogen levels fall within normal values.

    In adults, normal values are considered between 10 and 20 mg/dL, or between 3.6 and 7.1 mmol/L. In children, the healthy reference range is from 5 to 18 mg/dL or between 1.8 and 6.4 mmol/L. When the blood urea nitrogen values fall out of the reference range, it is very likely that there is some kind of abnormality in the body, most probably related to the kidney. Levels outside of the normal values could also indicate that something is wrong with the way your liver is processing proteins.

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    Why You Get The Bun Test

    Your doctor may order a BUN test as part of a routine checkup. It may be one of several blood tests that you get.

    If you have a kidney condition, the test is a way to check what your BUN levels are before you start a medication or treatment. Also, itâs standard for a BUN test to be given when youâre in the hospital for certain conditions.

    If your doctor suspects you may be getting kidney problems, they may order the BUN test.

    Tell your doctor if you have the following symptoms, which can be signs that something is wrong with your kidneys:

    â A change in how much you urinate

    â Pee that is foamy, bloody, discolored, or brown

    â Pain while you pee

    â Swelling in your arms, hands, legs, ankles, around your eyes, face, or abdomen

    â Pain in the mid-back where kidneys are located

    â Youâre tired all the time

    Pathophysiology Of Blood Urea Nitrogen And Blood Urea:

    Blood Urea Nitrogen, BUN, or Urea Nitrogen (BUN/Creatinine ratio ...
  • Blood urea molecule: O = C = 2 .
  • Urea production and BUN increase when more amino acids are metabolized in the liver.
  • This occurs with a high-protein diet, tissue breakdown, and or decreased protein synthesis.
  • While urea and BUN production is reduced in case of low protein intake and severe liver disease.
  • The urease enzyme can split urea into ammonia and carbon dioxide.
  • > 90% of the urea is excreted through the kidneys, the rest through GIT and skin.
  • Urea is freely filtered from the glomeruli.
  • 40% to 70% of the urea is highly diffusible and moves passively out of the renal tubule into the interstitium and ultimately enters the blood.
  • Blood Urea Nitrogen : Blood urea and action of urease enzyme

  • The molecular weight of urea = 60 grams
  • Each molecule contains 2 nitrogen = 28 grams. It is called blood urea nitrogen .
  • While in the SI unit, this is meaningless because it is reported as mmol/L.
  • The serum concentration of 28 mg/dL of urea-nitrogen is equivalent to 60 mg/dL of blood urea or 10 mmol/L of urea or urea-nitrogen in SI units.
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    High Blood Urea: Causes Symptoms And Treatments

    The urea It is a by-product derived by the human body when the liver is assimilating proteins and nitrogen compounds. It was discovered in 1932 by HA Krebs Y K. Henseleit, who noted that when ornithine or arginine was added, the liver began to produce a greater amount of ammonia.

    Its place of origin is the liver and is the result of a cycle known as the urea cycle. This substance is usually expelled from the body through urine, but when urea levels get too high in the blood It can bring terrible consequences such as kidney failure, liver failure, nervous system disorders, heart failure problems, among others.

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  • Blood Urea Normal Range In India

    The normal range of blood urea level in India can be interpreted from the table below:

    Blood urea level
    6-21mg/dl 14-17mg/dl

    The value has a wide range because it depends on many external factors. Blood urea level can change with age, health status, dietary intake, medicine intake, etc. of the patient.

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    Why Is Blood Urea Nitrogen Test Done

    A BUN test is a routine test ordered by your doctor during your checkup as part of a comprehensive metabolic panel or basic metabolic panel . It will be done if you are admitted to an emergency room or during a regular hospital stay.

    The BUN test may also be ordered as a precaution if you have risk factors for kidney disease. Early kidney disease doesnt have symptoms, but the following factors can put you at higher risk:

    The BUN test is often ordered if the doctor suspects your symptoms are signs of kidney disease. These include:

    • Fatigue

    What Causes High Blood Urea

    BUN (Blood Urea Nitrogen) Lab Value for Nursing Lecture | NCLEX Lab Values Course

    There are many diseases that can cause the amount present in the blood to increase markedly, for example, hypertension, kidney and liver failure, cirrhosis, gout or diabetes. To determine the levels of urea present in the body, doctors go to blood tests to know the levels of urea and creatinine, which allows them to know in what condition the kidneys are and if they are draining properly. Some other reasons that can cause it to increase can be:

    • A diet with too much protein
    • Dehydration problems
    • Bleeding in the gastrointestinal system
    • Exercising too hard and regularly

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