What Is a BUN-to-Creatinine Ratio Blood Test?

A BUN/Creatinine Ratio blood test is used in the differential diagnosis of acute or chronic renal disease, the diagnosis of reduced renal profusion, gastrointestinal bleeding, trauma, liver disease and urinary tract obstructions, according to Quest Diagnostics. The test looks for changes in the ratio of blood urea nitrogen to creatinine.

An increased BUN/Creatinine Ratio indicates reduced renal profusion, urinary tract obstruction and gastrointestinal bleeding. A decrease in the BUN/Creatinine Ratio indicates liver disease.

Chronic kidney disease gradually worsens over many months and years. Loss of function in the kidneys is a slow process, and renal disease often has few or no symptoms at the start of the disease, according to MedlinePlus. Symptoms typically become apparent during the end stage of renal disease. During end stage renal disease, the kidneys are no longer able to remove waste from the body. Dialysis or a kidney transplant are medically necessary at this point.

According to MedlinePlus, symptoms of kidney disease that occur after the kidneys have started to fail include abnormally dark or light skin, bone pain, drowsiness, numbness, foul breath and excessive thirst. Diabetes and high blood pressure are the most common causes of kidney disease. Autoimmune disorders, birth defects, toxic chemicals, certain medicines, problems with the arteries flowing to the kidneys and backward flow of urine into the kidneys (reflux nephropathy) are all causes of renal disease.