Lipoprint LDL Subfractions
Elevated low density lipoprotein cholesterol (LDL-C) is a well-known risk factor for coronary heart disease (CHD). The National Cholesterol Education Program’s Adult Treatment Panel recommends LDL-C levels be less than 100 mg/dL for patients with known CHD or with CHD Risk Equivalents such as type 2 diabetes mellitus, symptomatic carotid artery disease, or multiple CHD risk factors. As important as LDL-C is as a risk predictor, there are still many patients who have LDL-C levels less than 130 mg/dL but still have heart attacks.
Patients with high triglycerides and low HDL-C are especially likely to have atherogenic dyslipidemia which also includes mild elevations in LDL-C and the presence of small, dense LDL particles. Recent evidence has suggested that a preponderance of small LDL particles may be an independent risk factor for CHD. A recent paper from the Diabetes Atherosclerosis Intervention Study group found that in patients with LDL-C of <115 g/dL, progression of coronary artery disease was nearly 4 times greater in those with small LDL than in those with large LDL. Patients with small LDL had an equivalent risk for progression as those with LDL-C > 140 mg/dL (Vakkilainen et al. Circulation 2003;107:1733).
Although the NCEP does not currently recommend measuring LDL subfractions as a screening tool, it does acknowledge that detection of small LDL is a useful indicator of atherogenic dyslipidemia and the metabolic syndrome. The presence of small LDL particles also supports intensified therapeutic lifestyle changes. If small LDL particles accompany elevated triglycerides or low HDL-C in high risk persons, nicotinic acid or fibric acid derivatives can be included as a component of lipid lowering therapy (NCEP ATPIII Report, p. II-33).
Lipoprint is the only FDA-approved test for measuring LDL subfraction cholesterol levels. It reports out the LDL phenotype as type A, intermediate, or type B based on particle size. Pattern A indicates lower risk and pattern B higher risk for CHD. Sample requirement is 1 mL of serum or EDTA plasma. CPT code is 83716.
