A lipid panel generally includes total cholesterol, HDL-cholesterol (HDL-C), LDL-C, and triglycerides. Rather than measuring each particle specifically, we measure the 'cargo' of each class of particle. That is, we don't routinely measure the number of LDL particles, for example, instead we isolate the LDL particles (using specific detergents) and measure the total cholesterol of those particles. This is often abbreviates as LDL-C (LDL-cholesterol).
Likewise, HDL-C is measurement of the cholesterol in the lipoprotein HDL.
Cardiovascular disease (CVD) is associated with elevations in LDL-C; increased LDL-C in individuals puts them at risk for CVD. The opposite is true for HDL-C. One of the functions of this lipoprotein is to remove excess cholesterol, transporting it to the liver for reprocessing or excretion. To prevent cardiac disease, HDL-C levels should remain high, within a healthy reference range (see below for healthy ranges). If HDL is below this recommended range, steps are taken to try and raise the HDL-C concentration. LDL-C should be low, and there are multiple, effective drugs that can be used to lower LDL-C in patients.
The recommended ranges for lipids below are from the 2001 National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III). These were developed in the US as recommended levels that decrease risk for CHD in adults. Unlike other analytes, lipid and cholesterol levels are not based on a 'normal' population reference range. Rather, they are based on what patients should have, not what is normal. These are healthy targets rather than the mean ranges in a US population. Newer cholesterol guidelines (ATP IV) are expected in 2014 and will likely be even more aggressive as to the optimum healthy ranges they prescribe:
- Cholesterol<200 mg/dL
- Triglyceride<150 mg/dL
- LDL-C<100 mg/dL
- HDL-C>59 mg/dL