1. Why hasn’t the Direct LDL-C replaced the calculated LDL-C test?
Calculated LDL-C is about as accurate as direct LDL-C when triglyceride levels are normal. It can be done at no additional cost when a lipid profile is performed.
2. Are all LDL molecules the same?
No, LDL and other lipoprotein molecules vary in size and density. Patients with a larger percentage of small dense LDL molecules are believed to be at greater risk for atherosclerosis, than those with a higher percentage of large LDL. It is possible to separate out the different sizes of lipoprotein molecules by density (through centrifugation) or size and electrical charge (through electrophoresis). Commercial tests are available that use these separation techniques. However, the data are not clear on the clinical usefulness of these tests.
