LDL-P (LDL Particles) test measures the number of LDL cholesterol particles in the blood rather than the concentration of LDL cholesterol (LDL-C) measured by most current tests. The results of LDL-P test should be compared with the results of LDL-C test; when the results do not match (high LDL-P/normal LDL-C or normal LDL-P/high LDL-C), then, according to some authors, the LDL-P test results are considered a better predictor of the risk of cardiovascular disease (heart attack and stroke) than LDL-C results [29,37] . According to other authors, LDL-P test does not give better information about the coronary heart disease risk than total/HDL cholesterol ratio  .
Sterol lipids, such as cholesterol and its derivatives, are an important component of membrane lipids,  along with the glycerophospholipids and sphingomyelins. The steroids , all derived from the same fused four-ring core structure, have different biological roles as hormones and signaling molecules . The eighteen-carbon (C18) steroids include the estrogen family whereas the C19 steroids comprise the androgens such as testosterone and androsterone . The C21 subclass includes the progestogens as well as the glucocorticoids and mineralocorticoids .  The secosteroids , comprising various forms of vitamin D , are characterized by cleavage of the B ring of the core structure.  Other examples of sterols are the bile acids and their conjugates,  which in mammals are oxidized derivatives of cholesterol and are synthesized in the liver. The plant equivalents are the phytosterols , such as β-sitosterol , stigmasterol , and brassicasterol ; the latter compound is also used as a biomarker for algal growth.  The predominant sterol in fungal cell membranes is ergosterol . 
Some organizations [ clarification needed ] promote the use of injected phosphatidylcholine, otherwise known as injection lipolysis , claiming the procedure can break down fat cells, and thus serve as an alternative to liposuction . While the procedure cites early experiments that showed lipolysis in cases of fat emboli,  no peer-reviewed studies have shown any amount of lipolysis even remotely comparable to liposuction.   Injection of phosphatidyl choline in small numbers of patients has been reported to reduce or completely resolve a majority of lipomas , although some actually increased in size. There were side-effects, which resolved without complication. Long-term studies are deemed necessary to judge efficacy.   Dr. Patrick Treacy has used phosphatidylcholine and deoxcholate successfully in the treatment of infraorbital fat pads.