Apolipoprotein B, Plasma
Assessment of residual risk in patients at target non-HDL-C (or LDL-C)
Follow-up studies in individuals with non-HDL-C (or LDL-C) values inconsistent with risk factors or clinical presentation
Definitive studies of cardiac risk factors in individuals with significant family histories of coronary artery disease or other increased risk factors
Confirmation of suspected abetalipoproteinemia or hypobetalipoproteinemia
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Apolipoprotein B (ApoB) is the primary protein component of low-density lipoprotein (LDL). LDL contains a variable amount of cholesterol, but each LDL contains exactly 1 ApoB protein. Therefore, ApoB is a superior indicator of circulating LDL compared to LDL cholesterol (LDL-C). ApoB has been demonstrated to perform equally with LDL particles measured by nuclear magnetic resonance spectroscopy.(1)
ApoB is strongly associated with increased risk of developing cardiovascular disease (CVD) and often outperforms LDL-C at predicting risk of coronary heart disease.(2-4) Patients with acceptable non-HDL-C (or LDL-C) but elevated ApoB remain at higher risk of developing CVD; conversely, patients with acceptably low ApoB but moderate non-HDL-C or LDL-C elevations are at a reduced risk for CVD.(5,6) Finally, in 7 different placebo-controlled randomized clinical trials, on-statin reduction of ApoB was more closely related to CVD risk reduction than non-HDL-C or LDL-C.(7)
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
> or =18 years: 48-124 mg/dL
Reference values have not been established for patients that are <18 years of age.
It is well established that increased plasma concentration of Apo B-containing lipoproteins is associated with an increased risk of developing atherosclerotic disease. Case control studies have found plasma Apo B concentrations to be more discriminating than other plasma lipids and lipoproteins in identifying patients with coronary heart disease (CHD). The utility of Apo B in determining CHD risk has been confirmed by prospective studies, although the extent to which Apo B concentrations were better than serum lipids in predicting risk was variable. Apo B measurement offers greater precision than low-density lipoprotein (LDL) cholesterol determination, which is most often derived by calculation.
Abetalipoproteinemia and severe hypobetalipoproteinemia can cause malabsorption of food lipids and polyneuropathy. In patients with hyperapobetalipoproteinemia (HALB), a disorder associated with increased risk of developing CHD and with an estimated prevalence of 30% in patients with premature CHD, Apo B is increased disproportionately in relation to LDL cholesterol. Apo B quantitation is required to identify these patients and is necessary in distinguishing HALB from another common lipoprotein abnormality, familial combined hyperlipidemia.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Fasting for <12 hours or intake of alcohol during the 24 hours prior to specimen collection may invalidate test results.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Cole TG, Contois JH, Csako G, et al: Association of apolipoprotein B and nuclear magnetic resonance spectroscopy-derived LDL particle number with outcomes in 25 clinical studies: assessment by the AACC Lipoprotein and Vascular Diseases Division Working Group on best practices. Clin Chem 2013;59:752-770
2. Sierra-Johnson J, Fisher RM, Romero-Corral A, et al: Concentration of apolipoprotein B is comparable with the apolipoprotein B/apolipoprotein A-I ratio and better than routine clinical lipid measurements in predicting coronary heart disease mortality: findings from a multi-ethnic US population. Eur Heart J 2009;30(6):710-717
3. Steffen BT, Guan W, Remaley AT, et al: Use of lipoprotein particle measures for assessing coronary heart disease risk Post-American Heart Association / American College of Cardiology Guidelines: The Multi-Ethnic Study of Atherosclerosis. Arterioscler Thromb Vasc Biol 2015;35:448-454
4. Thompson A, Danesh J: Associations between apolipoprotein B, apolipoprotein AI, the apolipoprotein B/AI ratio and coronary heart disease: a literature-based meta-analysis of prospective studies. J Intern Med 2006;259:481-492
5. Mora S, Buring JE, Ridker PM: Discordance of low-density lipoprotein (LDL) cholesterol with alternative LDL-related measures and future coronary events. Circulation 2014;129:553-561
6. Pencina MJ, D’Agostino RB, Zdrojewski T, et al: Apolipoprotein B improves risk assessment of future coronary heart disease in the Framingham Heart Study beyond LDL-C and non-HDL-C. Eur J Prev Cardiol 2015;epub ahead of print
7. Thanassoulis G, Williams K, Ye K, et al: Relations of change in plasma levels of LDL-C, non-HDL-C and apoB with risk reduction from statin therapy: a meta-analysis of randomized trials. J Am Heart Assoc 2014;3:e000759