Plasma choline level analysis using High Performance Liquid Chromatography (HPLC) (Choline Level, by HPLC) is used to measure the concentration of choline in the blood, which is an essential compound for metabolism and nervous system health. Choline is necessary for liver health, as it contributes to fat regulation and the prevention of fatty liver disease. This test is also used to diagnose choline-related metabolic disorders, as well as to assess the nutritional status of individuals with choline deficiency or neurological diseases.