8/11/2019 Clinical Aspects of Serum Cholesterol Level

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CLINICAL ASPECTS OF SERUM CHOLESTEROL | Tutorial D-1 CVS 

130110110177|Gabriella Chafrina| 23/09/13 

The Serum Cholesterol is correlated with the Incidence of Atherosclerosis and Coronary Heart Disease

-  ↑ plasma cholesterol levels (>5,2 mmol/L) major factor in promoting atherosclerosis, triacylglycerol are an independent RF

-  Atherosclerosis is characterized by deposition of cholesterol and cholesteryl ester from plasma lipoproteins into the artery wall.

-  Prolonged elevation of levels of VLDL, IDL, chylomicron remnant, or LDL in blood (eg, DM, lipid nephrosis, hypothyroidism,

hyperlipidemia) are often accompanied by premature or severe atherosclerosis.

-  The inverse relationship between HDL concentration and coronary heart disease, making LDL:HDL cholesterol ratio is a good

predictive parameter

-  The American Heart Association endorses the National Cholesterol Education Programs (NCEP) guidelines for detection of high

cholesterol: All adults age 20 or older should have a fasting lipoprotein profile —  which measures total cholesterol, LDL (bad)

cholesterol, HDL (good) cholesterol and triglycerides once every five years. This test is done after a nine- to 12-hour fast without

food, liquids or pills.

8/11/2019 Clinical Aspects of Serum Cholesterol Level

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CLINICAL ASPECTS OF SERUM CHOLESTEROL | Tutorial D-1 CVS 

130110110177|Gabriella Chafrina| 23/09/13 

Factors Influence Serum Cholesterol:

1.  Hereditary factors: the greatest role in determining individual serum cholesterol,

2. 

Dietary factors : substitution in the diet of PUFA (corn oils and sunflower seed oils) and MUFA (olive oils) for saturated fatty acid.

One of the mechanisms involved is the up-regulation of LDL receptors by poly- and monounsaturated as compared with saturated

fatty acids  ↑ in the catabolic rate of LDL (main atherogenic lipoprotein) + formation of ↓  VLDL particles (contain relatively

more cholesterol and utilized by extrahepatic tissues at a slower rate than are larger particles)

3.  Environment/Lifestyle factors 

  Additional factors in coronary heart disease: high blood pressure, smoking, male gender, obesity (particularly abdominal

obesity), lack of exercise, and drinking soft as opposed to hard water

  Factors associated with elevation of plasma FFA followed by ↑ output of triacylglycerol and cholesterol into the circulation in

VLDL include emotional stress and coffee drinking. Premenopausal women appear protected related to the beneficial effects

of estrogen

  Regular exercise ↓ plasma LDL but ↑ HDL + triacylglycerol concentrations ↓ (due to ↑ insulin sensitivity   enhances the

expression of lipoprotein lipase)

When Diet Changes Fail, Hypolipidemic Drugs Will Reduce Serum Cholesterol & Triacylglycerol

  Statins: inhibiting HMG-CoA reductase and up-regulating LDL receptor activity. Ex: atorvastatin, simvastatin, fluvastatin, and

pravastatin.

  Other drugs used include fibrates such as clofibrate and gemfibrozil and nicotinic acid: ↓  plasma triacylglycerols by ↓  the

secretion of triacylglycerol and cholesterol-containing VLDL by the liver.

  Ezetimibe: blocking uptake via Neimann-Pick C like 1 protein   inhibit absorption of cholesterol by the intestine   ↓ bloodcholesterol levels. Belongs to azetidinone class of cholesterol absorption inhibitors.

Primary Disorders of the Plasma Lipoproteins (Dyslipoproteinemias) Are Inherited

Inherited defects in lipoprotein metabolism   primary condition of either hypo-  or hyperlipoproteinemia  (all of the primary

conditions are due to a defect at a stage in lipoprotein formation, transport, or destruction)

Reference: Harper’s Illustrated Biochemistry 28th

 edition; heart.org