Apolipoprotein B
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Apolipoprotein B (apoB) levels are used to evaluate the risk for cardiovascular disease.
The reference range of apoB levels in adults is less than 130 mg/dL (1.3 g/L).
ApoB levels are higher in males than in females and tend to increase with age.
It has been suggested the range be adjusted according to the risk factor stratification, [1] similar to LDL cholesterol (LDL-C).
Table 1. Treatment Goals for Total ApoB Relative to LDL-C Levels (Open Table in a new window)
Risk
ApoB
LDL-C
High risk: CHD or CHD risk equivalent
< 90 mg/dL
< 100 mg/dL
Moderate risk: ≥2 risk factors
< 110 mg/dL
< 130 mg/dL
Low risk: 0-1 risk factors
< 130 mg/dL
< 160 mg/dL
CHD, coronary heart disease
Table 2. ADA/ACC Consensus Report Treatment Goals in Patients with Cardiometabolic Risk and Lipoprotein Abnormalities [2] (Open Table in a new window)
Risk
ApoB
LDL-C
Non-HDL-C
Highest-risk patients: Known CVD or DM plus ≥1 additional major CVD risk factor
< 80 mg/dL
< 70 mg/dL
< 100 mg/dL
High-risk patients: ≥2 CVD risk factors but no DM or known CVD or DM but no other major risk factors
< 90 mg/dL
< 100 mg/dL
< 130 mg/dL
CVD, cardiovascular disease; DM, diabetes mellitus
Elevated apolipoprotein B (apoB) levels indicate an increased risk of cardiovascular disease. [3, 4, 5, 6]
ApoB levels may be increased during pregnancy or coffee consumption, as well as during the fall and winter seasons.
Low apoB levels may indicate Bassen-Kornzweig syndrome (abetalipoproteinemia), a very rare genetic condition characterized by apolipoprotein B deficiency.
Other conditions that are associated with low apoB levels include the following:
Liver cirrhosis
Specimen type: Plasma EDTA
Patient instruction: Overnight fasting (12-14 hours)
Collection tube: Lavender top (EDTA)
Unacceptable conditions: Hemolyzed specimens
Specimen preparation: Separate serum from cells as soon as possible or within 2 hours of collection and transfer 1 mL serum to transport tube
Storage/transport temperature: Refrigerated
Stability: Refrigerated 8 days; frozen 3 months
Panels: None
Apolipoprotein B (apoB) is a structural protein that constitutes a major component of the very-low-density lipoprotein (VLDL), the intermediate-density lipoprotein (IDL), and the low-density lipoprotein (LDL). Each of these lipoprotein particles carries one apoB molecule; as a result, the total serum apoB level corresponds to the total number of VLDL, IDL, and LDL particles.
Because VLDL, IDL, and LDL are considered atherogenic, the apoB level should reflect the atherogenic potential of these lipoproteins.
Cardiovascular risk is associated more with the number and size of circulating atherogenic particles than with the concentration of cholesterol in these particles. ApoB is not equivalent to non-LDL-C, because the latter reflects the cholesterol content of all atherogenic lipoproteins rather than the total number of circulating atherogenic particles.
ApoB plays a central role in carrying cholesterol and triglycerides from the liver and gut to utilization and storage sites.
Incontestable data support the concept that apoB is a better tool to assess cardiovascular disease than LDL-C and non-DHL-C.
Furthermore, apoB seems to be a very important parameter in assessing cardiovascular risk in the setting of diabetes and metabolic syndrome, since patients with these conditions tend to have small, dense LDL particles with relatively normal LDL-C but high apoB levels.
In addition, several clinical trials have shown that apoB is a better marker for monitoring patients on statin therapy for residual risk than LDL-C.
Finally, a Consensus Conference Report by the ADA/ACC has recommended the use of apoB level for risk assessment in persons at high risk for cardiometabolic disease.
Familial hypercholesterolemia is a rare disease caused by a mutation in the apoB gene code. Patients with the homozygous mutation tend to develop cardiovascular disease in childhood.
Overnight fasting might not be necessary to evaluate apoB levels, but most laboratories recommend it.
Some evidence has shown that the capacity of the apoB/apoA-I ratio in assessing cardiovascular risk is strong and may be better than the use of apolipoprotein B alone.
Grundy SM. Low-density lipoprotein, non-high-density lipoprotein, and apolipoprotein B as targets of lipid-lowering therapy. Circulation. 2002 Nov 12. 106(20):2526-9. [Medline].
Brunzell JD, Davidson M, Furberg CD, Goldberg RB, Howard BV, Stein JH. Lipoprotein management in patients with cardiometabolic risk: consensus conference report from the American Diabetes Association and the American College of Cardiology Foundation. J Am Coll Cardiol. 2008 Apr 15. 51(15):1512-24. [Medline].
Williams K, Sniderman AD, Sattar N, D’Agostino R Jr, Wagenknecht LE, Haffner SM. Comparison of the associations of apolipoprotein B and low-density lipoprotein cholesterol with other cardiovascular risk factors in the Insulin Resistance Atherosclerosis Study (IRAS). Circulation. 2003 Nov 11. 108(19):2312-6. [Medline].
Sipola-Leppänen M, Vääräsmäki M, Tikanmäki M, Hovi P, Miettola S, Ruokonen A, et al. Cardiovascular Risk Factors in Adolescents Born Preterm. Pediatrics. 2014 Sep 1. [Medline].
Corsetti JP, Gansevoort RT, Bakker SJ, Sparks CE, Vart P, Dullaart RP. Apolipoprotein B Attenuates Albuminuria-Associated Cardiovascular Disease in Prevention of Renal and Vascular Endstage Disease (PREVEND) Participants. J Am Soc Nephrol. 2014 May 22. [Medline].
Angelin B, Kristensen JD, Eriksson M, Carlsson B, Klein I, Olsson AG, et al. Reductions in serum levels of LDL cholesterol, apolipoprotein B, triglycerides and lipoprotein(a) in hypercholesterolaemic patients treated with the liver-selective thyroid hormone receptor agonist eprotirome. J Intern Med. 2014 Apr 22. [Medline].
, Myers GL, Christenson RH, Cushman M, Ballantyne CM, Cooper GR. National Academy of Clinical Biochemistry Laboratory Medicine Practice guidelines: emerging biomarkers for primary prevention of cardiovascular disease. Clin Chem. 2009 Feb. 55(2):378-84. [Medline].
Contois JH, McNamara JR, Lammi-Keefe CJ, Wilson PW, Massov T, Schaefer EJ. Reference intervals for plasma apolipoprotein B determined with a standardized commercial immunoturbidimetric assay: results from the Framingham Offspring Study. Clin Chem. 1996 Apr. 42(4):515-23. [Medline].
Davidson MH. Apolipoprotein measurements: is more widespread use clinically indicated?. Clin Cardiol. 2009 Sep. 32(9):482-6. [Medline].
Evans K, Laker MF. Intra-individual factors affecting lipid, lipoprotein and apolipoprotein measurement: a review. Ann Clin Biochem. 1995 May. 32 ( Pt 3):261-80. [Medline].
Harper CR, Jacobson TA. Using apolipoprotein B to manage dyslipidemic patients: time for a change?. Mayo Clin Proc. 2010 May. 85(5):440-5. [Medline].
http://labtestsonline.org/understanding/analytes/apob/tab/test. as accessed on. February 2012.
http://www.mayomedicallaboratories.com/test-catalog/Performance/80308. as accessed on. February 2012.
Mustad V, Derr J, Reddy CC, Pearson TA, Kris-Etherton PM. Seasonal variation in parameters related to coronary heart disease risk in young men. Atherosclerosis. 1996 Sep 27. 126(1):117-29. [Medline].
Walldius G, Jungner I, Holme I, Aastveit AH, Kolar W, Steiner E. High apolipoprotein B, low apolipoprotein A-I, and improvement in the prediction of fatal myocardial infarction (AMORIS study): a prospective study. Lancet. 2001 Dec 15. 358(9298):2026-33. [Medline].
Risk
ApoB
LDL-C
High risk: CHD or CHD risk equivalent
< 90 mg/dL
< 100 mg/dL
Moderate risk: ≥2 risk factors
< 110 mg/dL
< 130 mg/dL
Low risk: 0-1 risk factors
< 130 mg/dL
< 160 mg/dL
CHD, coronary heart disease
Risk
ApoB
LDL-C
Non-HDL-C
Highest-risk patients: Known CVD or DM plus ≥1 additional major CVD risk factor
< 80 mg/dL
< 70 mg/dL
< 100 mg/dL
High-risk patients: ≥2 CVD risk factors but no DM or known CVD or DM but no other major risk factors
< 90 mg/dL
< 100 mg/dL
< 130 mg/dL
CVD, cardiovascular disease; DM, diabetes mellitus
Georges Elhomsy, MD, ECNU, FACE Assistant Professor of Medicine, University of Kansas School of Medicine-Wichita
Georges Elhomsy, MD, ECNU, FACE is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Endocrinology, American College of Physicians, Endocrine Society, The Obesity Society
Disclosure: Received income in an amount equal to or greater than $250 from: Corcept and Novo-nordisk .
George T Griffing, MD Professor Emeritus of Medicine, St Louis University School of Medicine
George T Griffing, MD is a member of the following medical societies: American Association for the Advancement of Science, International Society for Clinical Densitometry, Southern Society for Clinical Investigation, American College of Medical Practice Executives, American Association for Physician Leadership, American College of Physicians, American Diabetes Association, American Federation for Medical Research, American Heart Association, Central Society for Clinical and Translational Research, Endocrine Society
Disclosure: Nothing to disclose.
Eric B Staros, MD Associate Professor of Pathology, St Louis University School of Medicine; Director of Clinical Laboratories, Director of Cytopathology, Department of Pathology, St Louis University Hospital
Eric B Staros, MD is a member of the following medical societies: American Medical Association, American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology
Disclosure: Nothing to disclose.
Apolipoprotein B
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