Increased urea formation can also increase the ratio, such as gastrointestinal bleeding and trauma, etc.Reduced kidney perfusion such as congestive heart failure or recent onset of urinary tract obstruction can lead to an increase in the BUN/Creatinine ratio.The BUN/Creatinine ratio helps with differential diagnosis of acute or chronic kidney disease.Some essential factors to know about BUN/Creatinine blood test When the BUN levels are studied with the creatinine levels, it gives a better picture of what is happening with the kidneys. It is the reason a creatinine test is also needed. The BUN level alone does not reveal much about kidney health. It allows the healthcare providers to assess how well the kidneys are functioning. Together, they help in measuring the overall kidney function. They can also determine gastrointestinal bleeding or trauma in some cases.īlood urea nitrogen and creatinine are both filtered in the kidney and excreted in the urine. And while they can be tested separately, the BUN/creatinine ratio can help pinpoint significant health issues. These tests reveal a lot about your metabolism, kidney, liver, and overall health. What Is a Bun/Creatinine Ratio Test?īUN (blood urea nitrogen) and creatinine are two blood tests used for diagnosing acute or chronic kidney damage or disease. The internal medicine doctors at the Century Medical and Dental Center focus on diagnosing your renal problems and use the test results to recommend the best treatment. The BUN/Creatinine ratio blood test measures the overall kidney functions and detects any sign of metabolic disease or liver damage. If you have a family history of kidney disease or suffer from diabetes and high blood pressure, get your BUN and creatinine ratio tested as urea and creatinine are filtered in the kidney and excreted in the urine. In particular, prerenal disease should not be excluded by a normal ratio since diminished urea production (due to decreased protein intake or underlying liver disease) can prevent the expected rise in BUN due to increased tubular reabsorption.Early kidney disease is a silent problem, and you may not know about it until you begin to feel the symptoms and it is too late to reverse it. In contrast to the potential utility of a high BUN/serum creatinine ratio, a normal ratio is of limited diagnostic utility. However, this problem is chronic and cannot explain an acute rise in the BUN out of proportion to any change in the serum creatinine concentration. The BUN/serum creatinine ratio can exceed 20:1 when loss of muscle mass in a chronically ill or older patient lowers creatinine production and, therefore, the serum creatinine concentration, independent of the GFR. The BUN will rise out of proportion to the serum creatinine when urea production is increased due to GI bleed (upper somewhat more than lower), tissue breakdown, or glucocorticoid therapy. Thus, a high ratio is suggestive of prerenal disease as long as some other cause of a high ratio is not present. The BUN/Cr ratio is normal at 10 to 15:1 in ATN (intrarenal), but is often greater than 20:1 in prerenal disease due to the increase in the passive reabsorption of urea that follows the enhanced proximal reabsorption of sodium and water. *** A BUN/Cr ratio that is high when BUN and Creatinine are either low or at the lower range of normal is not going to be clinically significant. In ATN, the reabsorption of BUN or secretion of Cr is decreased making the ratio to be normal. As they pass through the renal tubule, BUN is reabsorbed from the PCT (proximal convoluted tubule) while Creatinine is not reabsorbed but instead, more is secreted into the tube in the DCT. In normal circumstances, Both BUN and Cr are filtered. Renal damage causes reduced reabsorption of BUN, therefore lowering the BUN:Cr ratio. Some sources say the normal range is 10-15:1. Dehydration or hypoperfusion is suspected. BUN is disproportionately elevated relative to creatinine in serum.

Urea is made in the liver as a by-product of protein metabolism. *Note that BUN=Blood urea nitrogen which is essentially a measurement of urea. The ratio may be decreased with liver disease (due to a decrease in the formation of urea) and malnutrition. It may also be seen with increased protein, from BI bleed, or increased protein in the diet. An increased ratio may be due to a condition that causes a decrease in the flow of blood to the kidneys, such as CHF or dehydration. The ratio of BUN to creatinine is usually between 10:1 and 20:1. We may look at the BUN / Creatinine ratio to help determine the cause of renal failure.

What is the normal range for bun