High Cholesterol: Diagnosis Make an Appointment Refer a Patient Ask a Question Reviewed by Howard D. Weinberger, MD, FACC (July 01, 2019) Since there are usually no signs and symptoms of high blood cholesterol, a blood test is important to diagnose high blood cholesterol. Since there are usually no signs and symptoms of high blood cholesterol, a blood test is important to diagnose high blood cholesterol. High blood cholesterol is diagnosed by a blood test called a lipoprotein profile or lipid panel. This requires you to fast, so you cannot eat or drink anything for 10 to 12 hours or more before taking the test. Often people fast after dinner, until blood is drawn in the morning. The lipoprotein profile or lipid panel provides information about: Total cholesterol Low-density lipoprotein (LDL) or bad cholesterol level High-density lipoprotein (HDL) or good cholesterol level Triglycerides If it is not possible to get a lipoprotein profile or lipid panel done, knowing your total cholesterol and HDL cholesterol can give you a general idea about your cholesterol levels. High Cholesterol: Causes High Cholesterol: Treatment Clinical Trials For more than 100 years, National Jewish Health has been committed to finding new treatments and cures for diseases. Search our clinical trials.