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Test ID: LPAWS Lipoprotein (a) Cholesterol, Serum

Reporting Name

Lp(a) Cholesterol, S

Useful For

Evaluation of increased risk for cardiovascular disease and events:

-Most appropriately measured in individuals at intermediate risk for cardiovascular disease

-Patients with early atherosclerosis or strong family history of early atherosclerosis without explanation by traditional risk factors should also be considered for testing

-Follow-up evaluation of patients with elevations in lipoprotein (a) mass

Specimen Type

Serum


Specimen Required


Patient Preparation:

1. Fasting: 8 hours.

2. Patient must abstain from alcohol for 24 hours before collection.

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.


Specimen Minimum Volume

0.35 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  60 days

Reference Values

Lp(a) CHOLESTEROL

Normal: <5 mg/dL

 

LpX

Undetectable

Day(s) and Time(s) Performed

Monday through Friday; 10 a.m.

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

83700

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LPAWS Lp(a) Cholesterol, S 35388-8

 

Result ID Test Result Name Result LOINC Value
2849 Lp(a) Cholesterol 35388-8
23924 LpX 42178-4
23937 Interpretation 59462-2

Clinical Information

Lipoprotein (a) (Lp[a]) consists of an LDL particle that is covalently bound to an additional protein, apolipoprotein (a) (apo[a]). Apo (a) has high-sequence homology with the coagulation factor plasminogen and, like LDL, Lp(a) contains apolipoprotein B100 (apoB). Thus, Lp(a) is both proatherogenic and prothrombotic. Lp(a) is an independent risk factor for coronary heart disease (CHD), ischemic stroke, and aortic valve stenosis. Lp(a) has been referred to as "the most atherogenic lipoprotein." The mechanism of increased risk is unclear but most likely involves progression of atherosclerotic stenosis via intimal deposition of cholesterol and promotion of thrombosis via homology to plasminogen.

 

Concentrations of Lp(a) particles in the blood can be expressed readily by 2 methods: as concentrations of Lp(a) protein or as Lp(a) cholesterol. Mayo Clinic's Cardiovascular Laboratory Medicine measures and reports Lp(a) cholesterol individually (LPAWS / Lipoprotein [a] Cholesterol, Serum) and as a part of the lipoprotein profile (LMPP / Lipoprotein Metabolism Profile, Serum). The cholesterol content of Lp(a) particles varies little, and Lp(a) can contain significant proportions of the serum cholesterol.

 

Lp(a) is a highly heterogeneous particle mainly because of the variable number of kringle repeats in the apo(a) portion of the molecule. Kringles are specific structural domains containing 3 intra-strand disulfide bonds that are highly homologous to similar repeats found in plasminogen.

 

In the clinical laboratory, immunologic methods are generally used to quantify Lp(a) protein mass. Reagents for Lp(a) mass measurement are available from multiple manufacturers and although standardization efforts are underway, currently available methods are not standardized. Difficulties in standardizing Lp(a) mass measurement arise from the variability in signals produced by different reagents due to the size polymorphisms of apo(a). For this reason, some elevations of Lp(a) mass are associated with low levels of Lp(a) cholesterol. Lp(a) quantification can be done by densitometric measurement of Lp(a) cholesterol. This method measures only the cholesterol contained in the Lp(a) particles and is thus not influenced by the relative size of the apo(a) particle. Because Lp(a) cholesterol measurement is not influenced by apo(a) size, it may provide a more specific assessment of cardiovascular risk than Lp(a) mass measurement. Lp(a) cholesterol measurement may be used in concert with Lp(a) mass determination or may be used as a stand-alone test for assessment of risk.

Interpretation

Increased lipoprotein (a) (Lp[a] cholesterol has been associated with increased risk for the development of atherothrombotic disease. Aggressive LDL reduction is the recommended treatment approach in most patients with increased Lp(a).

 

Patients with increased Lp(a) cholesterol values have an approximate 2-fold increased risk for developing cardiovascular disease events.

 

Lipoprotein-X (LpX) is an abnormal lipoprotein that appears in the sera of patients with obstructive jaundice, and is an indicator of cholestasis. The presence of LpX will be reported if noted during Lp(a) cholesterol analysis.

Clinical Reference

1. Baudhuin L, Bryant S, Spears G, et al: Lipoprotein(a) Cholesterol But Not Lipoprotein(a) Mass is Significantly Correlated with Angiographic Coronary Artery Disease and Major Adverse Events. Atherosclerosis 2018; Jun (32):46

2. Berg K: Lp(a) lipoprotein: an overview. Chem Phys Lipids 1994;67-68:9-16

3. Rhoads GG, Dahlen G, Berg K et al: Lp(a) lipoproteins as a risk factor for myocardial infarction. JAMA 1986;256:2540-2544

4. Bostom AG, Cupples LA, Jenner JL, et al: Elevated plasma lipoprotein(a) and coronary heart disease in men aged 55 years and younger. A prospective study. JAMA 1996;276:544-548

5. Ridker PM, Hennekens CH, Stampfer MJ: A prospective study of lipoprotein(a) and the risk of myocardial infarction. JAMA 1993;270:2195-2199

6. Tsimikas S, Brilakis ES, Miller ER, et al: Oxidized phospholipids, Lp(a) lipoprotein, and coronary artery disease. N Engl J Med 2005;353(1):46-57

7. Baudhuin LM, Hartman SJ, O'Brien JF, et al:  Electrophoretic measurement of lipoprotein(a) cholesterol in plasma with and without ultracentrifugation: comparison with an immunoturbidimetric lipoprotein(a) method. Clin Biochem 2004 June;37[6]:481-488

8. McConnell JP, Baudhuin LM, Berger PB, et al: Lipoprotein (a) cholesterol, but not Lp(a) mass, is an independent predictor of angiographic coronary artery disease and subsequent cardiovascular events in patients referred for coronary angiography. Circulation 2007;116:II_818

Analytic Time

2 days (not reported on Saturday or Sunday)

Method Name

Electrophoresis/Enzyme Staining/Densitometry

Forms

If not ordering electronically, complete, print, and send a Cardiovascular Test Request Form (T724) with the specimen.

Mayo Clinic Laboratories | Cardiology Catalog Additional Information:

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