Também conhecido como
Lipoprotein little a
Nome formal
Lipoprotein (a)
Este artigo foi revisto pela última vez em
Este artigo foi modificado pela última vez em
24 de Maio de 2018.
De relance
Por que fazer este exame?

To give your doctor additional information about your risk of developing heart disease; as part of a targeted screen for coronary artery disease (CAD) and cerebrovascular disease (CVD)

Quando fazer este exame?

When you have a family history of elevated Lp(a) levels and/or a family history of premature CAD; when you have heart disease but your lipid profile is normal or shows only mildly elevated levels of cholesterol and/or low-density lipoprotein cholesterol (LDL-C)

Amostra:

A blood sample drawn from a vein in your arm

O que está sendo pesquisado?

Lp(a) may be an independent risk factor for heart disease; i.e., patients with acceptable lipid levels but elevated Lp(a) are still at risk for heart disease. It is a lipoprotein, consisting of an LDL molecule attached to another protein, Apolipoprotein (a). In the body, Apolipoprotein (a) can interfere with the function of plasminogen (resulting in blood clot formation) and can help bind LDL molecules to artery walls (speeding up plaque formation and the narrowing and hardening of the arteries). It is this dual action that may explain the role of Lp(a) in the promotion of cardiovascular disease.

Lp(a) levels are genetically determined and will remain fairly constant in an individual over a lifetime; their levels are not affected by diet, exercise, and other typical lifestyle modifications used to lower lipid levels. They can rise a bit higher in post menopausal women. Lp(a) levels also vary by ethnicity; those patients of African American descent tend to have levels 3 to 4 times higher than Caucasians but, for reasons that are not well understood yet, they do not have a higher risk for CAD.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

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 complete lipid profile, fasting for at least 12 hours may be required.

Accordion Title
Perguntas frequentes
  • Como o exame é usado?

    Lp(a) is not currently routinely ordered. It may be ordered along with other lipid tests to selectively screen for risk factors for coronary artery disease (CAD) and cerebral vascular disease. Lp(a) and several other emerging cardiac risk markers (such as Apo B, hs-CRP, Apo A, and homocysteine levels) are ordered on patients who have a strong family history of premature coronary artery disease.

    Some doctors may also order these tests on patients with existing heart or vascular disease, especially those who have normal or only mildly elevated lipids. Since about 50% of the people who have heart attacks have normal cholesterol levels, doctors are starting to look at other factors that may have an influence on heart disease. It is thought that elevated Lp(a) levels can exacerbate other heart and vascular disease processes.

  • Quando o exame é pedido?

    Lp(a) may be ordered, along with other lipid tests, when you have a family history of premature coronary artery disease and when your doctor suspects a familial hypercholesterolemia. He may also order an Lp(a) level when you have had a stroke or heart attack but have normal or only mildly elevated lipids.

    In rare cases, an Lp(a) level may be ordered on a post menopausal woman to see if elevations in Lp(a) (tied to decreasing estrogen levels) have significantly increased her risk of developing CAD.

  • O que significa o resultado do exame?

    Lp(a) levels are genetically determined and remain relatively constant over an individual's lifetime. They are not affected by lifestyle changes or by most drugs.

    High Lp(a) levels may increase a person's risk for developing coronary artery disease and cerebral vascular disease and can occur in patients with a normal lipid profile. Elevated levels of Lp(a) are thought to work independently, to add to any underlying heart or vascular disease processes. Other conditions that may cause elevated levels of Lp(a) include:

    Low levels of Lp(a) do not appear to cause problems.

  • Há mais alguma coisa que eu devo saber?

    Lp(a) levels are not routinely ordered tests. A National Cholesterol Education Program (NCEP) guideline, the “Adult Treatment Panel III” (pg. II-21, available in PDF) acknowledged the possible usefulness of Lp(a) and other emerging cardiac risk tests like Lp(a), but it did not recommend them for widespread screening. The National Academy of Clinical Biochemistry (NACB) guidelines for emerging biomarkers of cardiovascular disease and stroke also recommend testing for individuals with a strong family history of premature risk of CVD or those with intermediate cardiovascular risk but not for general screening.

    This is partially due to the fact that Lp(a) levels are genetically determined and difficult to change. Niacin and estrogen (for postmenopausal women) have been shown to lower Lp(a) levels a small amount, but their effect appears to be short term, and it is not known if lowering Lp(a) levels actually lowers risk. Experts are currently not recommending drug treatments for elevated Lp(a) levels, but some are suggesting that patients with elevated Lp(a) levels should be especially vigilant about lowering their low-density lipoprotein (LDL – the “bad” cholesterol) levels, which may help lower their overall risk.

    In general, lipids should not be measured during a fever or major infection, within four weeks of an acute myocardial infarction (heart attack), a stroke, or major surgery, right after excessive alcohol intake, with severely uncontrolled diabetes, when a woman is pregnant, or during rapid weight loss.

  • Why would my doctor want to order an Lp(a) more than once?

    Typically, Lp(a) levels are only tested once because they are usually fairly constant. Occasionally, your doctor may order a second Lp(a) to confirm the initial level or to see if your risk has increased significantly after menopause or to monitor the effects of treatment.

Páginas relacionadas

Neste site

Exames relacionados: Lipid Profile, Homocysteine, hs-CRP, Apo A, Apo B

Conditions: Heart attack, Stroke, Congestive heart failure, Angina

Em outros sites da Internet

American Heart Association
National Academy of Clinical Biochemistry, Laboratory Medicine Practice Guidelines: Emerging Biomarkers of Cardiovascular Disease and Stroke (This is a downloadable PDF file.)
National Institutes of Health, Adult Treatment Panel III Report on High Blood Cholesterol , pg. II-21 (This is a downloadable PDF file.)

Fontes do artigo

NOTA: Este artigo se baseia em pesquisas que incluíram as fontes citadas e a experiência coletiva de Lab Tests Online Conselho de Revisão Editorial. Este artigo é submetido a revisões periódicas do Conselho Editorial, e pode ser atualizado como resultado dessas revisões. Novas fontes citadas serão adicionadas à lista e distinguidas das fontes originais usadas.

 

S1
Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

S2
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

S3
Spengler, R. (2002 May 14, Updated). What is lipoprotein(a)? [6 paragraphs]. St. Joseph Health System, Health Library [On-line information]. Available FTP: http://www.sjo.org/library/healthguide/MedicalTests/topic.asp?hwid=tv6799abc

S4
Paxton, A. (2002 July). One Year Later, Cholesterol Guidelines Sinking In [51 paragraphs]. In the News, CAP Today Feature Story [On-line article]. Available FTP: http://www.cap.org/captoday/archive/2002/cholesterol_guidelines_feature.html

S5
Lipoprotein(a). [2 paragraphs]. ARUP's Guide to Clinical Laboratory Testing (CLT) [On-line information]. Available FTP: http://www.aruplab.com/guides/clt/tests/clt_a48b.htm#1141226

S6
Sih, I., Contributor. Chapter 63. Lipoprotein Disorders [66 paragraphs]. The Merck Manual of Geriatrics, Section 8: Metabolic and Endocrine Disorders [On-line information]. Available FTP: http://www.merck.com/pubs/mm_geriatrics/sec8/ch63.htm

S7
(2000 July 21). Genetics of Coronary Heart Disease [46 paragraphs]. WebMD Health [On-line information]. Available FTP: http://my.webmd.com/content/article/1675.50290

S8
Apgar, B. (1999 February 15). Oral vs. Transdermal HRT to Reduce Lipoprotein(a) Levels [6 paragraphs]. American Family Physician, Tips from Other Journals [On-line Journal]. Available FTP: http://www.aafp.org/afp/990215ap/tips.html#Oral

S9
Stewart, C. (2001 February 8). Lecture 6: Cholesterol and Lipoproteins [40 paragraphs]. Lecture notes, Biol 366, Univ at Albany, NY [On-line lecture]. Available as PDF file: http://www.albany.edu/faculty/cs812/bio366/L06_lipoproteins.pdf

S10
Lipoprotein Structure and Function [29 paragraphs]. Cardiovascular Chemistry Group at Texas A&M University [Website information]. Available FTP: http://www.chem.tamu.edu/rgroup/macfarlane/problem3.htm

S11
Simon lecture, transcribed by Jessy (2001 December 14). Cardiology 35: Lipids and CVD [34 paragraphs]. SUNY Stony Brook School of Medicine Class of 2004 [On-line lecture notes]. Available FTP: http://www.stonybrookmed.com/noteservice/2004/Lectures/cardio/cardio35.doc

S12
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO., Pp 110-114.

S13
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.

S14
Harrison’s Principles of Internal Medicine, 16th edition. Kasper, Braunwald, Fauci, Hauser, Longo, Jameson, eds. McGraw Hill: 2005.

S15
(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 FTP: http://clevelandclinicmeded.com/ccjm/sept1999/ccjmoneminutesep99.htm

S16
(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 FTP: http://www.medscape.com/viewarticle/544893

S17
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 (accessed online Sept. 2007). Available FTP: http://www.medscape.com/medline/abstract/16985228