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26123 Lipoprotein (a), Serum (LIPA1)

Lipoprotein (a), Serum (LIPA1)
Test Code: LIPA1SO
Synonyms/Keywords
​Lipoprotein (a), S
Lipoprotein a
Lp(a) apoprotein
LP "little-A"
Useful For
Cardiovascular disease (CVD) risk refinement in patients with moderate or high risk based on conventional risk factors or patients with clinical suspicion of residual CV risk not identified by other lipid parameters
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​Serum ​Serum Separator Tube (SST) ​Red Top Tube (RTT) ​1 mL ​0.5 mL ​
Collection Processing Instructions
Separate serum from red blood cells within 1 hour of collection. Aliquot specimen into a sterile plastic tube for transport.
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​Refrigerate (preferred) ​7 days
​Frozen ​30 days
​Ambient​24 hours
Rejection Criteria
​
Gross Hemolysis
​Gross Lipemia
​Gross Icterus
Interference

Epidemiologic studies have shown lipoprotein (a) (Lp[a]) concentrations are lowest in non-Hispanic white, Chinese, and Japanese populations. The Hispanic population has a slightly higher median Lp(a) concentration, and, in the African American population, the median Lp(a) serum concentration is approximately 2 times higher than in the white population.

In very rare cases, gammopathy, type IgM (Waldenstrom macroglobulinemia) in particular, may cause unreliable results.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories ​Monday through Sunday ​1-3 day Immunoturbidimetric Assay
Reference Lab
Mayo Clinic Laboratories
Test Information

Lipoprotein (a) consists of a low-density lipoprotein (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.

Accurate immunochemical measurement of Lp(a) is complicated by the heterogeneity of Lp(a) molecular size. Due to the large number of polymorphisms (varying number of kringle domain repeats in the Apo[a] protein) in the population, any given individual can have an Apo(a) protein between 240 to 800 kDa. This heterogeneity leads to inaccuracies in all immunoassay. In addition, the degree of atherogenicity of the Lp(a) particle may depend on the molecular size of the Lp(a)-specific protein. However, the measurement of Lp(a) using immunoassays calibrated to molar units is recommended to minimize assay inaccuracies caused by Apo(a) isoform size.

Serum concentrations of Lp(a) are related to genetic factors, specifically the expression of Apo(a), and are largely unaffected by diet, exercise, and lipid-lowering pharmaceuticals. However, in a patient with additional modifiable CHD risk factors, more aggressive therapy to normalize these factors may be indicated if the Lp(a) value is also increased. In cases of extremely elevated Lp(a), lipoprotein apheresis may be considered.

Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories

> or =18 years: <75 nmol/L

Values > or =75 nmol/L may suggest increased risk of coronary heart disease.

Values > or =175 nmol/L is considered a risk-enhancing factor for cardiovascular disease by several professional societies. Clinician-patient discussion of therapeutic strategy is warranted.

Reference values have not been established for patients who are less than 18 years of age. 

Interpretation

Lipoprotein (a) (Lp[a]) concentrations of 75 nmol/L and above is linearly related to increased risk of cardiovascular events independent of conventional risk markers.

Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​83695 ​ ​1 ​Lipoprotein (a) ​
Synonyms/Keywords
​Lipoprotein (a), S
Lipoprotein a
Lp(a) apoprotein
LP "little-A"
Ordering Applications
Ordering Application Description
​COM Lipoprotein (a), Serum (LIPA1)
​Cerner​Lipoprotein (a), Serum (LIPA1)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​Serum ​Serum Separator Tube (SST) ​Red Top Tube (RTT) ​1 mL ​0.5 mL ​
Collection Processing
Separate serum from red blood cells within 1 hour of collection. Aliquot specimen into a sterile plastic tube for transport.
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​Refrigerate (preferred) ​7 days
​Frozen ​30 days
​Ambient​24 hours
Rejection Criteria
​
Gross Hemolysis
​Gross Lipemia
​Gross Icterus
Interference

Epidemiologic studies have shown lipoprotein (a) (Lp[a]) concentrations are lowest in non-Hispanic white, Chinese, and Japanese populations. The Hispanic population has a slightly higher median Lp(a) concentration, and, in the African American population, the median Lp(a) serum concentration is approximately 2 times higher than in the white population.

In very rare cases, gammopathy, type IgM (Waldenstrom macroglobulinemia) in particular, may cause unreliable results.

Useful For
Cardiovascular disease (CVD) risk refinement in patients with moderate or high risk based on conventional risk factors or patients with clinical suspicion of residual CV risk not identified by other lipid parameters
Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories

> or =18 years: <75 nmol/L

Values > or =75 nmol/L may suggest increased risk of coronary heart disease.

Values > or =175 nmol/L is considered a risk-enhancing factor for cardiovascular disease by several professional societies. Clinician-patient discussion of therapeutic strategy is warranted.

Reference values have not been established for patients who are less than 18 years of age. 

Interpretation

Lipoprotein (a) (Lp[a]) concentrations of 75 nmol/L and above is linearly related to increased risk of cardiovascular events independent of conventional risk markers.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories ​Monday through Sunday ​1-3 day Immunoturbidimetric Assay
Reference Lab
Mayo Clinic Laboratories
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​83695 ​ ​1 ​Lipoprotein (a) ​
For most current information refer to the Marshfield Laboratory online reference manual.