Lipid profile

Lipid profile or lipid panel is a panel of blood tests that serves as an initial screening tool for abnormalities in lipids, such as cholesterol and triglycerides. The results of this test can identify certain genetic diseases and can determine approximate risks for cardiovascular disease, certain forms of pancreatitis, and other diseases.

Lipid profile
MeSH-
MedlinePlus003491
eMedicine-
LOINC24331-1, 57698-3

Lipid panels are ordered as part of a physical exam, along with other panels such as the complete blood count (CBC) and basic metabolic panel (BMP).

Components

The lipid profile typically includes:

Using these values, a laboratory may also calculate:

The lipid profile tests are of 7 types:

  • Total lipids
  • Serum total cholesterol
  • serum HDL cholesterol
  • Total cholesterol/HDL cholesterol ratio
  • Serum triglycerides
  • Serum Phospholipids
  • Electrophoretic fractionation to determination percentage of
    • (a) Chylomicrons
    • (b) LDL
    • (c) VLDL
    • (d) HDL

Procedure and indication

Recommendations for cholesterol testing come from the Adult Treatment Panel (ATP) III guidelines, and are based on many large clinical studies, such as the Framingham Heart Study.

For healthy adults with no cardiovascular risk factors, the ATP III guidelines recommend screening once every five years.[1] A lipid profile may also be ordered at regular intervals to evaluate the success of lipid-lowering drugs such as statins.

In the pediatric and adolescent population, lipid testing is not routinely performed. However, the American Academy of Pediatrics and the National Heart, Lung, and Blood Institute (NHLBI) recommend that children aged 9–11 be screened once for severe cholesterol abnormalities.[2] This screening can be valuable to detect genetic diseases such as familial hypercholesterolemia that can be lethal if not treated early.

Traditionally, most laboratories have required patients to fast for 9–12 hours before screening. However, studies have questioned the utility of fasting before lipid panels, and some diagnostic labs routinely accept non-fasting samples.[3][4][5][6]

Typically the laboratory measures only three quantities: total cholesterol; HDL; Triglycerides. From these three data LDL may be calculated. According to Friedewald's equation:[7]

  • LDL = Total cholesterol - HDL - Triglycerides/5

Other calculations of LDL from those same three data have been proposed which yield some significantly different results.[8]

VLDL may be defined as the total cholesterol that is neither HDL nor LDL. Then Friedewald's equation mentioned above yields:

  • VLDL = Triglycerides/5

The alternative calculations mentioned above may yield significantly different values for VLDL.

Implications
See also: LDL and HDL

This test is used to identify dyslipidemia (various disturbances of cholesterol and triglyceride levels), many forms of which are recognized risk factors for cardiovascular disease and rarely pancreatitis.

A total cholesterol reading can be used to assess an individual's risk for heart disease, however, it should not be relied upon as the only indicator. The individual components that make up total cholesterol reading—LDL, HDL, and VLDL—are also important in measuring risk.

For instance, someone's total cholesterol may be high, but this may be due to very high HDL ("good cholesterol") cholesterol levels,—which can actually help prevent heart disease (the test is mainly concerned with high LDL, or "bad cholesterol" levels). So, while a high total cholesterol level may help give an indication that there is a problem with cholesterol levels, the components that make up total cholesterol should also be measured.

References
  1. National Cholesterol Education Program (Ncep) Expert Panel On Detection, E. (2002). "Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report". Circulation. 106 (25): 3143–3421. doi:10.1161/circ.106.25.3143. PMID 12485966.
  2. "Pediatric Cardiovascular Risk Reduction Guidelines - NHLBI, NIH". Archived from the original on 2012-11-16.
  3. Sidhu, D.; Naugler, C. (2012). "Fasting Time and Lipid Levels in a Community-Based Population: A Cross-sectional Study / Fasting Time and Lipid Levels". Archives of Internal Medicine. 172 (22): 1–4. doi:10.1001/archinternmed.2012.3708. PMID 23147400.
  4. Nordestgaard BG, Langsted A, Mora S, Kolovou G, Baum H, Bruckert E, et al. (July 2016). "Fasting is not routinely required for determination of a lipid profile: clinical and laboratory implications including flagging at desirable concentration cut-points-a joint consensus statement from the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine". Eur. Heart J. 37 (25): 1944–58. doi:10.1093/eurheartj/ehw152. PMC 4929379. PMID 27122601.
  5. Mora S (July 2016). "Nonfasting for Routine Lipid Testing: From Evidence to Action". JAMA Intern Med. 176 (7): 1005–6. doi:10.1001/jamainternmed.2016.1979. PMID 27119719.
  6. Anderson, Laura N.; Maguire, Jonathon L.; Lebovic, Gerald; Hanley, Anthony J.; Hamilton, Jill; Adeli, Khosrow; McCrindle, Brian W.; Borkhoff, Cornelia M.; Parkin, Patricia C.; Birken, Catherine S. (1 January 2017). "Duration of Fasting, Serum Lipids, and Metabolic Profile in Early Childhood". The Journal of Pediatrics. 180: 47–52.e1. doi:10.1016/j.jpeds.2016.09.005. ISSN 0022-3476. Retrieved 17 November 2020.
  7. Friedewald WT, Levy RI, Fredrickson DS (1972). "Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge". Clin. Chem. 18 (6): 499–502. doi:10.1093/clinchem/18.6.499. PMID 4337382.CS1 maint: multiple names: authors list (link) (Cited in: Clin. Chem. 1990; 36:15-19).
  8. "Calculating Your Cholesterol".

Further reading
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