Causes of a High Level of BUN and Creatine

The blood urea nitrogen (BUN) test, in conjunction with the creatinine test is primarily used to evaluate kidney functioning. You should be able to identify the primary bodily functions associated with BUN and creatine, in order to properly understand the causes for the high levels of these compounds. In addition to kidney failure, high levels of BUN and creatine are also associated with muscle stress and dehydration. Learn to identify the symptoms that are attributable to these ailments, prior to requesting blood work from a licensed medical professional.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Urea is a waste product that comes from the break down of protein. Urea is made in the liver and passed out of the body as urine, through the kidneys. Alone, this substance is non-toxic. However, high readings of blood urea nitrogen may signal heart failure or dehydration. BUN levels should be read in conjunction with creatinine recordings to determine whether your kidneys are functioning properly.

The University of Maryland Medical Center describes creatine as an amino acid, or protein building block 1. Creatine kinase (CK) is a process that occurs within skeletal muscle tissue to release stores of energy. Creatinine is a CK byproduct; and is also filtered out of the bloodstream through your kidneys. Similar to BUN, creatine itself is not harmful, but its presence may be an indicator of other problems.


Exercise places stress upon your muscle cells, which release creatine into the blood stream while using energy and repairing themselves. The National Institutes of Health documents elevated creatine levels for college football players during two-a-day practices 2.

Intense exercise may also lead to dehydration. According to the Oxford Journals, dehydrated patients “reflect a low urine flow rate,” and the reabsorption of urea by the kidneys. Elevated BUN levels may signal that your body is unable to remove wastes effectively, because of dehydration. Of course, additional tests would be necessary.

Muscle Trauma and Heart Failure

The Muscular Dystrophy Association indicates that muscle cells “break open” during degeneration. Creatine that is usually found within your muscles now enters the bloodstream because of this damage. The heart is a large muscle and extreme levels of creatine do predict and confirm heart attacks.

High BUN levels may also be the consequence of a lack of blood flow to the kidneys, due to heart failure.

Kidney Disease

Taken together, high levels of BUN and creatine are often an indicator of kidney disease. The blood urea nitrogen to creatinine ratio has been devised to measure this relationship and arrive at a diagnosis. A high BUN to creatinine ratio may signal dehydration, while lower BUN to creatinine ratios could indicate kidney disease. BUN and creatinine readings both increase when your kidneys are not functioning properly.

Kidneys work to remove waste; and high levels of BUN and creatinine signal that these byproducts are not being taken out of your body as urine.

Symptoms and Tests

Investigate having blood work performed if you are experiencing nausea, light-headedness or extreme fatigue. People that carry a family history of heart, cardiac and neuromuscular illnesses should be certain to alert their physician regarding these happenings. Further, changes in the consistency and color of your urine are also symptoms of kidney disease that should be evaluated.

Avoid excessive exercise and high protein intake prior to undergoing BUN and creatinine tests.