Waste product tests are a group of blood tests that measure the levels of specific waste products (natural byproducts of metabolism) in the blood. An abnormal test result can help in the diagnosis of gout and can indicate kidney disease, a common complication of lupus, sickle cell anemia, diabetes and other conditions.

In patients with certain inflammatory diseases, waste product tests may be ordered for numerous reasons, including:

• To check the levels of uric acid in patients suspected of having gout
  
  
• To test kidney function when problems are suspected
  
  
• To monitor treatment of kidney disease
  
  
• To check kidney function before starting or while taking certain drugs
  

Patients may be instructed to refrain from eating for four to eight hours before a waste product test. In addition, they may be ordered to reduce or stop use of some of their medications and vitamins because some substances can interfere with the results of the tests. Patients are advised to make sure that their physician has a list of all medications and vitamins that are being taken.