TOTAL CHOLESTEROL It is generally agreed that the normal range for total cholesterol is rather wide. Serum total cholesterol is slightly higher in men than in women. It is a little lower in persons under 20 years but rises with age. It does not appear to be much altered following meals (unlike triglyceride). In pregnancy there is an increase which may reach 20% above normal at the 30th week.

lipid profile The lipid profile is used as an index of its possible effect in precipitating atherosclerosis. The following table is usually used for its interpretation: Serum total cholesterol < 5 mmol/L (<200 mg%) HDL-Cholesterol Low risk >1.4mmol/L (>55 mg%) High risk <0.9 mmol/L (<35 mg%) LDL-Cholesterol Low risk <3.4 mmol/L (<130 mg%) High risk >4.1 mmol/L (>160 mg%) VLDL-Cholesterol Low risk <.45 mmol/L (<37 mg%) Atherogenic index Low risk 6 High risk) Serum Phospholipids 57 – 89 mmol/L (175 – 275 mg%)

Hypercholesterolaemia Increases are found most characteristically in the primary hypercholesterolaemia (particularly types II, III and IV), nephrotic syndrome, hypothyroidism, obstructive jaundice, primary biliary cirrhosis and diabetes mellitus.

Raised serum cholesterol signifies hypercholesterolaemia which is considered to be a cardiovascular risk factor that may predispose to coronary thrombosis appearing as angina pectoris or myocardial infarction.

Hypocholesterolaemia Decreases are not so well defined. Conditions that may create hypocholesterolaemia include hyperthyroidism, malabsorption syndrome malnutrition and pernicious anaemia. Very low values occur in a beta lipoproteinaemia. Therapeutic reduction of serum cholesterol is seen during administration of lipid lowering drugs such as clofibrate, cholestyramine and nicotinic acid.

Measurement of Serum Cholesterol Principle Serum cholesterol is measured by the following enzymatic reactions; Cholesterol esters+ H2O Cholesterol esterase Cholesterol+ Fatty acids Cholesterol+O2 Cholesterol Oxidase 4-Cholesten-3-One+H2O2 2H2O2+4-aminoantipyrine Peroxidase Red quinine + 4 H2O By measuring the absorbency of the red quinine at 500 nm and comparing with standard solution of cholesterol treated in the same way and applying lamberts and Beers low, the concentration of the test can be found.