• Creatinine. A non-protein waste product of creatine (a component of muscle) metabolism. The amount of creatinine in the body is proportional to the amount of each patient’s muscle mass. Abnormally high levels usually indicate damage of 50 percent or more of the kidney. Because creatine levels do not rise significantly until kidney damage is extensive, creatinine levels are often used in conjunction with other waste product tests to determine the severity of suspected kidney disease.

  • Uric acid. Uric acid is the end product of the normal breakdown of purines that are a part of many foods. In conjunction with other waste product tests, this test can be used to assess how well the kidneys are functioning. Uric acid is normally found in urine but higher levels (hyperuricemia) may indicate a number of conditions, including gout, liver disease and some types of cancer.  Gout is a painful joint inflammation caused by excessive amounts of uric acid in the blood and deposits of excess uric acid crystals (urates) in and around the joints, especially the big toe. Studies also show high uric acid levels are a risk factor for heart disease and may indicator of heart failure.  In addition, uric acid levels be elevated in people who eat high-protein diets.

  • Blood urea nitrogen (BUN). Urea is the main product of protein metabolism, containing about 40 to 50 percent of the non-protein nitrogen in the body. It is produced by the liver and excreted from the body by the kidneys. If there is an increased amount produced by the liver or a decreased amount excreted by the kidneys, the level of urea will rise. BUN levels are a good indicator of whether or not patients are eating enough protein. They also aid in diagnosing congestive heart failure, kidney disease and urinary tract obstructions. In addition, BUN levels may rise following a heart attack.