Clinical Review

YOU HAVE A NEW JOB: Monitor the lipid profile

OBG Manag. 2008 December;20(12):45-53

References

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2. Biggerstaff KD, Wooten JS. Understanding lipoproteins as transporters of cholesterol and other lipids. Adv Physiol Educ. 2004;28:105-106.

3. Nordestgaard BG, Wooten R, Lewis B. Selective retention of VLDL, IDL and LDL in the arterial intima of genetically hyperlipidemic rabbits in vivo. Molecular size as a determinant of fractional loss from the intima-inner media. Arterioscler Thromb Vasc Biol. 1995;15:534-542.

4. Brunzell JD, Davidson M, Furberg CD, et al. Lipoprotein management in patients with cardiometabolic risk. Consensus statement from the American Diabetes Association and the American College of Cardiology Foundation. Diabetes Care. 2008;31:811-822.

5. Barter PJ, Ballantyne CM, Carmena R, et al. ApoB versus cholesterol in estimating cardiovascular risk and in guiding therapy: report of the thirty-person/ten-country panel. J Intern Med. 2006;259:247-258.

6. 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;358:2026-2033.

7. Mudd JO, Borlaug BA, Johnson PV, et al. Beyond low-density lipoprotein cholesterol: defining the role of low-density lipoprotein heterogeneity in coronary artery disease. J Am Coll Cardiol. 2007;50:1735-1741.

8. Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA. 2001;285:2486-2497.

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15. Cromwell WC, Otvos JD, Keyes MJ, et al. LDL particle number and risk of future cardiovascular disease in the Framingham Off spring Study—implications for LDL management. J Clin Lipidol. 2007;1:583-592.

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17. Mora S, Szklo M, Otvos JD, et al. LDL particle subclasses, LDL particle size, and carotid atherosclerosis in the Multi-Ethnic Study of Atherosclerosis (MESA). Atherosclerosis. 2007;192:211-217.

18. Liu J, Sempos CT, Donahue RP, et al. Non-high-density lipoprotein and very-low-density lipoprotein cholesterol and their predictive risk values in coronary heart disease. Am J Cardiol. 2006;98:1363-1368.

19. National Cholesterol Education Program. Recommendations on lipoprotein measurement from the Working Group on Lipoprotein Measurement. National Institutes of Health. National Heart, Lung, and Blood Institute. NIH Publication No. 95-3044. Bethesda, Md: September 1995.

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TABLE 4

Lipid markers of remnant lipoproteins

Triglyceride (TG) >150–200 mg/dL
Very-low-density lipoprotein cholesterol >30 mg/dL
Unremarkable low-density lipoprotein cholesterol with elevated non-high-density lipoprotein cholesterol (HDL-C)
Low HDL-C in insulin-resistant patients
Elevated total cholesterol/HDL-C ratio and TG >150 mg/dL

A few words of advice

The driving forces of atherogenesis are increased numbers of apoB-containing lipoproteins and impaired endothelial integrity. ApoB and LDL-P are the available lab assays that most accurately quantify atherogenic particle number.

The lipid-concentration surrogates that you should be using to better predict apoB and CVD risk are:

TC (unless HDL-C is very high)
LDL-C
Non-HDL-C
TC/HDL-C ratio
TG/HDL-C ratio.

Because LDL is by far the most numerous of the apoB particles present in plasma, it is the primary agent of atherogenesis. However, apoB and LDL-P do not correlate with LDL-C when LDL particles are small, are TG-rich and cholesterol-poor, or simply cholesterol-poor (seen in some patients who have low LDL-C levels).^7,15

Both NCEP ATP-III and AHA Women’s Guidelines use the TC/HDL ratio as a powerful risk predictor. However, as a goal of therapy, these guidelines recommend normalizing LDL-C and then non-HDL-C.^8,11 In reality, normalization of non-HDL-C takes care of LDL-C as well. For example, say a patient has LDL-C <100 mg/dL, but non-HDL-C >130 mg/dL or TC/HDL-C ratio >4. These readings indicate residual risk and suggest that an elevated number of apoB particles is present. Therapy to normalize non-HDL-C or, better yet, apoB/LDL-P, is warranted. The clue that residual risk is present even when LDL-C is normal is the reduction of HDL-C and elevation of TG and non-HDL-C.