Results of some tests are more effectively evaluated on a specimen collected from a patient who is fasting. Fasting means nothing to eat or drink, with the exception of moderate amounts of water, for a period of between 8 to 12 hours. Tests for glucose, HDL, triglycerides,and panels of tests such as BMP (Basic Metabolic Panel), CMP (Comprehensive Metabolic Panel), or Lipid Panel that include these tests require a fasting specimen. Other common laboratory tests such as Prothrombin Time (PT), CBC, Dilantin, PSA, etc. do not require a fasting specimen. Please consult the test menu for specific specimen requirements.