Lipoprotein(a)

CPT: 83695
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Test Details

Synonyms

  • Lp "Little a"

Test Includes

Quantitation of Lp(a)

Use

Lp(a) determination is intended for use in conjunction with clinical evaluation, patient risk assessment, and other lipid tests to evaluate disorders of lipid metabolism and to assess coronary heart disease in specific populations.

Limitations

Lp(a) is an independent risk factor for coronary artery disease and cerebral infarction (in white populations) equal to high LDL cholesterol. Serum concentrations are genetically determined. Fifteen percent to 20% of the white population have Lp(a) levels ≥75 nmol/L and are presumed to be at risk. Race-dependent differences in Lp(a) concentrations are known. Significance of high Lp(a) in nonwhite populations must be evaluated with caution.

The Lp(a) levels in different ethnic populations can vary widely. Africans, or people of African descent, generally have Lp(a) levels higher than Caucasians and Asians, while Native Americans generally have levels lower than Caucasians. This variability of Lp(a) levels by ethnic population requires careful interpretation of results based on a knowledge of the patient and other cardiac risk factors that may be present.1

Methodology

Immunoturbidimetric

Reference Interval

<75 nmol/L; values ≥75 nmol/L may indicate independent risk factor for CHD.

Additional Information

Measurement of lipoprotein(a) is now recommended in several patient subgroups for whom excess lipoprotein(a) may have important clinical consequences: (1) patients with premature atherosclerosis, (2) patients with a strong family history of premature coronary heart disease (CHD), (3) patients with elevated LDL-C and greater than or equal to two risk factors, (4) patients who have had coronary angioplasty in whom lipoprotein(a) excess may increase the risk of restenosis, and (5) patients who have undergone coronary bypass graft surgery in whom Lp(a) excess may be associated with graft stenosis.2,3

Lipoprotein(a) has been called a powerful predictor of premature atherosclerotic vascular disease.2 As an independent risk factor for premature coronary artery disease, excess Lp(a) concentrations are associated with an increased risk of cardiac death in patients with acute coronary syndromes and with restenosis after angioplasty (PTCA) and coronary bypass procedures. In general, concentrations greater than or equal to 75 nmol/L of Lp(a) in serum are associated with a two- to sixfold increase in risk, depending on the presence of other risk factors.

Specimen Requirements

Specimen

Serum (preferred) or plasma

Volume

0.5 mL

Minimum Volume

0.2 mL

Container

Red-top tube, gel-barrier tube, lavender-top (EDTA) tube, green-top (heparin) tube, or blue-top (citrate) tube

Patient Preparation

Intake of alcohol, aspirin, niacin, and estrogen supplements have the potential of causing a misrepresentation of true Lp(a) concentrations.

Collection

Separate serum or plasma from cells as soon as possible (within two hours).

Storage Instructions

Refrigerate. Stable refrigerated for 14 days or frozen (if greater than 14 days)

Causes for Rejection

Grossly hemolyzed, lipemic, or icteric specimens

Clinical Information

Footnotes

1. Rifai N, Warnick GR, Dominiczak MH, eds. Handbook of Lipoprotein Testing. Washington DC: AACC Press;1997: 294-297.
2. Stein JH, Rosenson RS. Lipoprotein Lp(a) excess and coronary heart disease. Arch Intern Med. 1997; 157(11):1170-1176. 9183227
3. Wu AH, Contois JH, Cole TG. Reflex testing I: Algorithm for lipid and lipoprotein measurement in coronary heart disease risk assessment. Clin Chim Acta. 1999; 280(1-2):181-193. 10090535

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
120188 Lipoprotein (a) 43583-4 120190 Lipoprotein (a) nmol/L 43583-4

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