Of the diagnostic methods available to veterinarians, the clinical chemistry test has developed into a valuable aid for localizing pathologic conditions. This test is actually a collection of specially selected individual tests. With just a small amount of whole blood or serum, many body systems can be analyzed. Some of the more common screenings give information about the function of the kidneys, liver, and pancreas and about muscle and bone disease. There are many blood chemistry tests available to doctors. This paper covers the some of the more common tests.
Blood urea nitrogen (BUN) is an end-product of protein metabolism. Like most of the other molecules in the body, amino acids are constantly renewed. In the course of this turnover, they may undergo deamination, the removal of the amino group. Deamination, which takes place principally in the liver, results in the formation of ammonia. In the liver, the ammonia is quickly converted to urea, which is relatively nontoxic, and is then released into the bloodstream.
In the blood, it is readily removed through the kidneys and excreted in the urine. Any disease or condition that reduces glomerular filtration or increases protein catabolism results in elevated BUN levels.
Creatinine is another indicator of kidney function. Creatinine is a waste product derived from creatine. It is freely filtered by the glomerulus and blood levels are useful for estimating glomerular filtration rate. Muscle tissue contains phosphocreatinine which is converted to creatinine by a nonenzymatic process. This spontaneous degradation occurs at a rather consistent rate (Merck, 1991).
Causes of increases of both BUN and creatinine can be divided into three major categories: prerenal, renal, and postrenal. Prerenal causes include heart disease, hypoadrenocorticism and shock. Postrenal causes include urethral obstruction or lacerations of the ureter, bladder, or urethra. True renal disease from glomerular,