Diagnosis and Assessment of Disease
Basic Lipid/Lipoprotein Physiology ÎLipoproteins can be categorized by their:
• Buoyancy (density) • Surface protein content (apolipoproteins B [apoB] and A-I [apoA-I]) • Particle concentration (very low-density lipoprotein particle [VLDL-P], LDL-P, intermediate density lipoprotein particle [IDL-P], high-density lipoprotein particle [HDL-P])
• Cholesterol content (total cholesterol [TC], HDL-C, LDL-C, VLDL-C) • All can be used to assess atherosclerotic risk to varying degrees, but current evidence is that atherogenic particle concentrations (number) are more related to risk and are superior to conventional lipid concentrations as goals of therapy.
Table 1. Definitions22 ApoA-I
ApoB
HDL-C HDL-P
hs-CRP IDL-P
LDL-C LDL-P
LDL size Collective estimate of all of the apolipoprotein A-I containing lipoproteins
Collective concentration of all of the apolipoprotein B containing lipoproteins
Cholesterol content within all of the HDL particles in a dL of plasma
Number of HDL particles in a liter of plasma (μmol/L); This represents all sized HDL particles—large, medium, and small.
High sensitivity C-reactive protein – nonspecific inflammatory marker which is a CVD risk factor at levels ≥ 2.0 mg/dL up to 10 mg/dL
Number of IDL particles in a liter of plasma (nmol/L)
Cholesterol content within all the IDL and LDL particles in a dL of plasma
Number of LDL particles in a liter of plasma (expressed in nmol/L). This represents all sized LDL particles, large and small.
Diameter of the predominant LDL species
Pattern or phenotype A refers to predominantly larger, buoyant LDL particles
Pattern or phenotype B refers to predominantly smaller, dense LDL particles
Lp(a) Lp(a)-C Lp-PLA2
TC TG
VLDL-C VLDL-P 2 Concentration of apo(a) in a dL of plasma
Cholesterol content of LDL particles that have apo(a) attached Lipoprotein phospholipase A2 – atheroma specific inflammatory marker
Non-HDL-C The cholesterol within all of the apoB particles in a dL of plasma
Small LDL-P Number of small and intermediate LDL particles per liter of plasma (nmol/L)
Cholesterol content within every lipoprotein in a deciliter of plasma
Triacylglycerol concentration within all of the TG-trafficking lipoproteins in a dL of plasma
Cholesterol content within all of the VLDL particles in a dL of plasma (note: National Cholesterol Education Program [NCEP] recommends using VLDL-C as your surrogate of remnant-C)
Number of VLDL particles in a liter of plasma (nmol/L)
