For a basic metabolic panel, a red- or green-top tube should be filled with at least 2.5 to 2.8 milliliters of blood. Most institutions have policies regarding these lab tests that should be followed carefully.
According to the UC Davis Health System, it is important to ensure that the appropriate procedures are followed for obtaining a blood sample. First, the patient must be correctly identified. The necessary supplies should be gathered and easily accessible. The tubes must also be filled in the proper order and handled correctly. Finally, it is very important that the specimens are labeled with the correct patient identification information.