Department

Biochemistry

Preferred Sample Type

Lipoprotein a (Lp (a))

Suitable Specimen Types

  • Serum
  • EDTA Plasma
  • Li Hep Plasma
1 mL blood

Sample Processing in Laboratory

Usual

Sample Preparation

Samples are batched for analysis twice a week. Samples may be stored at 4 °C for 14 days without significant decrease.

Turnaround Time

1 week

Sample Stability

Samples are batched for analysis twice a week. Samples may be stored at 4 °C for 14 days without significant decrease.

Lipoprotein a (Lp (a))

General Information

Lipoprotein (a) [Lp(a)] is made in the liver and then enters the bloodstream. Elevated plasma concentrations of Lp(a) are a risk factor for coronary heart disease, cerebrovascular disease, atherosclerosis, thrombosis and stroke. High Lp(a) levels increases the risk of plaque thrombosis possibly by the following mechanism. Lp(a) accumulates in the vessel wall and inhibits binding of plasminogen to the cell surface which increases clotting by reducing plasmin. Inhibition of plasminogen also promotes proliferation of smooth muscle cells. Lp(a) concentrations may be affected by disease state. Niacin and aspirin are known to reduce levels of Lp(a) in some individuals.

Lp(a) is composed of two polypeptide components Apolipoprotein (a) [apo(a)] and a LDL-like protein containing Apolipoprotein B-100. These are connected via a disulfide bond. The interindividual variation in Lp(a) levels is 90% genetically determined by the LPA locus, a large gene found on chromosome 6. Apo(a) is a large protein encoded by LPA and is composed of a signal peptide region, many repeating kringle domains and a protease domain.

Measurement of Lp(a) levels is still relatively new though assays have been available for a number of years. This is mainly because of differences in assay and a lack of understanding of the clinical relevance of results. There has been recent interest in Lp(a), however levels should only be interpreted other lipid tests and clinical evaluation. It has been reported that elevated levels have been seen in nephritic syndrome, patients undergoing renal disease, patients with uncontrolled diabetes mellitus and hyopthyroidism.

 

Patient Preparation

None

Notes

Serum from standard sampling tubes and plasma from Li heparin, Na heparin, Na EDTA, K EDTA are acceptable.

Reference Range

Increased coronary risk over 30 mg/dL.

Specifications

  • EQA Scheme?: Yes
  • EQA Status: UK NEQAS Lipids

The laboratories at Heartlands Hospital, Good Hope Hospital and Solihull Hospital form part of the services provided by University Hospitals Birmingham and are UKAS (United Kingdom Accreditation Service) accredited to the ISO 15189:2012 standard. For a list of accredited tests and other information please visit the UKAS website using the following link: https://www.ukas.com/find-an-organisation/

  • Heartlands, Good Hope and Solihull Hospital pathology laboratories are a UKAS accredited medical laboratory No.8217
  • United Kingdom Health Security Agency laboratory is a UKAS accredited medical laboratory No.8213

Tests not appearing on the UKAS Schedule of Accreditation currently remain outside of our scope of accreditation. However, these tests have been validated to the same high standard as accredited tests and are performed by the same trained and competent staff.

For further test information, please visit the test database: http://www.heftpathology.com/frontpage/test-database.html.

Protection of personal information - Laboratory Medicine comply with the Trust Data Protection policy and have procedures in place to allow the Directorate and its employees to comply with the Data Protection act  1998 and associated best practice and guidance.

For further information contact Louise Fallon, Quality Manager, 0121 424 1235

UKAS HEFT