To measure lithium salt, the procedure is typically carried out on a blood sample. Individuals with bipolar disorder have their lithium levels monitored through the blood intravenously and sent to a laboratory for analysis. Lithium salt of heparin at concentration of 10-20 iu/ml of blood is typically used as an anticoagulant for gas analysis and emergency testing. This test is particularly useful because it does not affect the size of the red blood cells and reduces the risk of lysis occurring after blood has been withdrawn. These samples are often used for immunophenotyping.