Recently, there has been increased discussion around non-fasting cholesterol testing. This is an appropriate dialogue because testing needs to be convenient and easy to help facilitate patient compliance. However; it is important that non-fasting cholesterol testing is appropriate for the clinical circumstances in which it is to be used.
Historically, determination of cholesterol levels has involved looking at the low density lipoprotein (LDL-C) fraction, which is more predictive of cardiovascular outcomes than total cholesterol. However, this has required a fasting sample to maintain accuracy. The Friedewald equation, which subtracts high density lipoprotein cholesterol (HDL-C) and 20 percent of the triglyceride level from total cholesterol, is an indirect method that has been used to determine LDL-C. While this equation is reasonably accurate in patients with “normal” fasting triglyceride values, it is inaccurate when triglycerides are elevated, thus creating the need for patients to fast ahead of their cholesterol blood draws.
From an epidemiological perspective, HDL-C is viewed as a protective predictor of cardiac events, and it is also part of the non-fasting total cholesterol (TC) measurement. One alternative to fasting LDL-C that is unaffected by the patient’s fasting stature is measurement of non-HDL cholesterol (non-HDL-C): TC – HDL-C = non-HDL-C.
Listen to Dorothy Adcock, MD, Chief Medical Officer for Med lab Diagnostics; discuss non-HDL and its utilization in current guideline-supported treatment:
Information about Med lab’s full range of test options, including fasting and non-fasting non-HDL-C measures, is outlined in the LABupdate, Lipids in Atherosclerotic Cardiovascular Disease (ASCVD) Risk Assessment and Management (below).
1. Blaha MJ, Blumenthal RS, Brinton EA, Jacobson TA, National Lipid Association Taskforce on Non HDLC. The importance of non-HDL cholesterol reporting in lipid management. Journal ofclinical lipidology 2008;2:267-73.
2. Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem1972;18:499-502.