At a Glance
Why Get Tested?
When to Get Tested?
When you have a family history of CVD at a young age; when you have heart disease or have had a heart attack or stroke but your lipid profile is normal or shows only mildly elevated cholesterol and/or low-density lipoprotein cholesterol (LDL-C)
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None; however, Lp(a) is often performed at the same time as a lipid profile and fasting for 9-12 hours may be required for the lipid profile.
The Test Sample
What is being tested?
Lipoprotein (a) or Lp(a) is one type of lipoprotein that carries cholesterol in the blood. It is similar to low-density lipoprotein (LDL, the "bad" cholesterol) in that it contains a single apolipoprotein B protein along with cholesterol and other lipids. This test measures the amount of Lp(a) in the blood to help evaluate a person's risk of developing cardiovascular disease (CVD).
Like LDL, Lp(a) is considered a risk factor for CVD. The amount of Lp(a) that a person has is genetically determined and remains relatively constant over an individual's lifetime. A high level of Lp(a) is thought to contribute to a person's overall risk of CVD, making this test potentially useful as a cardiovascular risk marker.
The protein portion of Lp(a) consists of:
- Apolipoprotein B (Apo B) – a protein that is involved in the metabolism of lipids and is the main protein constituent of lipoproteins such as LDL and very low-density lipoprotein (VLDL)
- Apolipoprotein(a) – A second protein component, called apolipoprotein(a), which is attached to the Apo B. Apolipoprotein(a) has an unusual structure and is thought to inhibit clots from being broken down normally. The size of the apolipoprotein(a) portion of Lp(a) varies in size from person to person and tends to be smaller in Caucasians than in those of African ancestry. The significance of the variation in size in contributing to CVD risk is complex, but there is some evidence that smaller size increases risk. Most Lp(a) tests do not measure the size of apolipoprotein(a), however. They measure and report only the level of Lp(a) in blood.
Since about 50% of the people who have heart attacks have a normal cholesterol level, researchers have sought other factors that may have an influence on heart disease. It is thought that Lp(a) may be one such factor. Lp(a) has two potential ways to contribute. First, since Lp(a) can promote the uptake of LDL into blood vessel walls, it may promote the development of atherosclerotic plaque on the walls of blood vessels. Secondly, since apo(a) has a structure that can inhibit enzymes that dissolve clots, Lp(a) may promote accumulation of clots in the arteries. For these reasons, Lp(a) may be more atherogenic than LDL.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed; however, since this test may be performed at the same time as a lipid profile, fasting for 9-12 hours may be required.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Subhi, Y. (Updated 2014 April 1). Lipoprotein (a). Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2088118-overview through http://emedicine.medscape.com. Accessed April 2014.
Ye, Z. et. al. (2014). The Association Between Circulating Lipoprotein(a) and Type 2 Diabetes Is It Causal? Medscape Multispecialty from Diabetes. 2014;63(1):332-342 [On-line information]. Available online at http://www.medscape.com/viewarticle/818745 through http://www.medscape.com. Accessed April 2014.
Voora, D. (2012 December 12). Should We Test Lipoprotein(a) to Predict Risk for Atherosclerosis? Medscape Multispecialty [On-line information]. Available online at http://www.medscape.com/viewarticle/775752 through http://www.medscape.com. Accessed April 2014.
Boudi, F. and Ahsan, C. (Updated 2013 December 5). Risk Factors for Coronary Artery Disease. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/164163-overview through http://emedicine.medscape.com. Accessed May 2014.
Zieve, D. (2012 June 4). Lipoprotein-a. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007262.htm through http://www.nlm.nih.gov. Accessed April 2014.
(© 1995–2014). Lipoprotein (a), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/81558 through http://www.mayomedicallaboratories.com. Accessed May 2014.
Delgado, J. et. al. (2014 March 14). Cardiovascular Disease (Non-traditional Risk Markers) - Risk Markers - CVD (Non-traditional). ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CVDRiskMarkerNontrad.html?client_ID=LTD through http://www.arupconsult.com. Accessed May 2014.
Stone, N. et. al. (2013 November 12). 2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines Circulation. 2013;00:000–000. [On-line information]. Available online at http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437738.63853.7a through http://circ.ahajournals.org. Accessed May 2014
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 112-116.
Malaguarnera M, et. al. Lipoprotein(a) in Cardiovascular Diseases. Biomed Res Int. 2013; 2013: 650989. Published online Dec 30, 2012. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591100/ through http://www.ncbi.nlm.nih.gov. Accessed June 2014.
Jane Hoover-Plow and Menggui Huang. Lipoprotein(a) Metabolism: Potential Sites for Therapeutic Targets. Metabolism. Apr 2013; 62(4): 479–491. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547132/ through http://www.ncbi.nlm.nih.gov. Accessed June 2014.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Spengler, R. (2002 May 14, Updated). What is lipoprotein(a)? St. Joseph Health System, Health Library [On-line information]. Available online at http://www.sjo.org/library/healthguide/MedicalTests/topic.asp?hwid=tv6799abc through http://www.sjo.org.
Paxton, A. (2002 July). One Year Later, Cholesterol Guidelines Sinking In. In the News, CAP Today Feature Story [On-line article]. Available online at http://www.cap.org/captoday/archive/2002/cholesterol_guidelines_feature.html through http://www.cap.org.
Lipoprotein(a). ARUP's Guide to Clinical Laboratory Testing (CLT) [On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_a48b.htm#1141226 through http://www.aruplab.com.
Sih, I, Contributor. Chapter 63. Lipoprotein Disorders. The Merck Manual of Geriatrics, Section 8: Metabolic and Endocrine Disorders [On-line information]. Available online at http://www.merck.com/pubs/mm_geriatrics/sec8/ch63.htm through http://www.merck.com.
(2000 July 21). Genetics of Coronary Heart Disease. WebMD Health [On-line information]. Available online at http://my.webmd.com/content/article/1675.50290 through http://my.webmd.com.
Apgar, B. (1999 February 15). Oral vs. Transdermal HRT to Reduce Lipoprotein(a) Levels. American Family Physician, Tips from Other Journals [On-line Journal]. Available online at http://www.aafp.org/afp/990215ap/tips.html#Oral through http://www.aafp.org.
Stewart, C. (2001 February 8). Lecture 6: Cholesterol and Lipoproteins. Lecture notes, Biol 366, Univ at Albany, NY [On-line lecture]. PDF available for download at http://www.albany.edu/faculty/cs812/bio366/L06_lipoproteins.pdf through http://www.albany.edu/.
Lipoprotein Structure and Function. Cardiovascular Chemistry Group at Texas A&M University [Website information]. Available online at http://www.chem.tamu.edu/rgroup/macfarlane/problem3.htm through http://www.chem.tamu.edu.
Simon lecture, transcribed by Jessy (2001 December 14). Cardiology 35:Lipids and CVD. SUNY Stony Brook School of Medicine Class of 2004 [On-line lecture notes]. Available online at http://www.stonybrookmed.com/noteservice/2004/Lectures/cardio/cardio35.doc through http://www.stonybrookmed.com.
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO., Pp 110-114.
Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Winter, W. and Harris, N. Chapter 21: Lipoprotein Disorders, pp 251-259.
Harrison's Principles of Internal Medicine, 16th edition. Kasper, Braunwald, Fauci, Hauser, Longo, Jameson, eds. McGraw Hill: 2005.
(September 1999) The Cleveland Clinic, Center for Continuing Education, Cleveland Clinic Journal of Medicine: Should One Routinely Screen for Lipoprotein (a)? [Online information, accessed August 2007). Available online at http://clevelandclinicmeded.com/ccjm/sept1999/ccjmoneminutesep99.htm through http://clevelandclinicmeded.com.
(September 2006) High Lipoprotein(a) Levels Plus High LDL Increases CVD Risk in Women. Nainggolan L. Medscape Medical News (online information, accessed August 2007). Available online at http://www.medscape.com/viewarticle/544893 through http://www.medscape.com.
Suk Danik J; Rifai N; Buring JE; Ridker PM. Lipoprotein(a), measured with an assay independent of apolipoprotein(a) isoform size, and risk of future cardiovascular events among initially healthy women. JAMA. 2006; 296(11):1363-70. Available online at http://www.medscape.com/medline/abstract/16985228 through http://www.medscape.com. Accessed Sept 2007.
Zieve, D. and Dugdale, D. (Updated 2010 May 23). Lipoprotein-a. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007262.htm. Accessed September 2010.
Delgado, J. et. al. (Updated 2010 April). Cardiovascular Disease (Non-traditional Risk Markers) - Risk Markers - CVD (Non-traditional). ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CVDRiskMarkerNontrad.html?client_ID=LTD through http://www.arupconsult.com. Accessed September 2010.
(© 1995–2010). Unit Code 81558: Lipoprotein (a), Serum. Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/81558 through http://www.mayomedicallaboratories.com. Accessed September 2010.
Myers, G. Editor (© 2009). Emerging CV Risk Factors. The National Academy of Clinical Biochemistry, Laboratory Medicine Practice Guidelines, Emerging Biomarkers for Primary Prevention of Cardiovascular Disease and Stroke [On-line information]. Available online at http://www.aacc.org/members/nacb/LMPG/OnlineGuide/PublishedGuidelines/risk/Pages/default.aspx through http://www.aacc.org. Accessed September 2010.
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 110-114.
Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 254.
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 678-681.
Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, Pp 202-203.
Jill Rubin, Thomas A. Pearson, Roberta G. Reed, and Lars Berglund. Fluorescence-based, Nonradioactive Method for Efficient Detection of the Pentanucleotide Repeat (TTTTA)n Polymorphism in the Apolipoprotein(a) Gene. Clinical Chemistry Oct 2001; 47: 1758 - 1762.