Total Blood Cholesterol

If your cholesterol level is less than 5.2 mmol/L, that is reassuring. Unless you have other risk factors, such as a family history of heart disease, low HDL cholesterol, high blood pressure, cigarette smoking or diabetes mellitus, your risk of heart attack is relatively low. Even with a low risk cholesterol level, it is still a good ideal to follow a heart-healthy diet, since keeping your cholesterol level well below 5 mmol/L reduces your heart disease risk even further.

If you total cholesterol is in the 5 to 6 mmol/L range, you have twice the risk of heart attack as compared to your risk if your level was well below 5 mmol/L. But don’t feel alone: 45% of Canadian adults are in this group. Cholesterol readings in this range mean you should watch out for other risk factors, have your cholesterol re-checked, and modify your diet and activity to attempt to reduce your level to below 5 mmol/L.


Your LDL-cholesterol level greatly affects your risk of heart attack. In fact, LDL-cholesterol is a better predictor of heart attack risk than total blood cholesterol. When your LDL-cholesterol is over 4.5 mmol/L you are at high risk; when it’s between 3.5 and 4.5 mmol/L, you are at borderline-high risk. Ideally your LDL-cholesterol should be below 3.5 mmol/L. However, as with total cholesterol, the lower the level, the less the risk. If you have a history of heart disease, stroke, vascular disease, aneurysm or type 2 diabetes, the ideal LDL–cholesterol is between 1.5 and 2.5 mmol/L, and probably between 1.5 and 2.0 mmol/L. Medications will likely be required to achieve and maintain these levels.


In the average man, HDL-cholesterol levels are usually in the range of 1.1-1.4 mmol/L; in women from 1.3-1.6 mmol/L. HDL-cholesterol levels less than 1.0 mmol/L are considered abnormally low. Increasing HDL-cholesterol levels can significantly reduce the risk of heart disease. Weight loss, quitting smoking and most importantly, increasing aerobic exercise, are the best ways to raise the level of HDL-cholesterol. Having high triglycerides also reduces HDL-cholesterol and thus, increased the risk of heart attack. Female sex hormones (estrogens) and moderate alcohol intake are two other factors which can increase HDL levels.


To obtain an accurate measurement of your triglyceride level, it is necessary to have a blood sample taken after an overnight fast. Triglyceride levels above 2.0 mmol/L are considered elevated. Excess body fat, poorly controlled diabetes and excessive alcohol intake are common causes of elevated blood triglycerides. The clustering or risk factors including high triglycerides, low HDL, obesity, hypertension and impaired fasting blood sugar are called the Metabolic Syndrome. Weight loss, reduction in alcohol intake, increased activity and better control of diabetes often normalize triglyceride levels.


Lipoprotein (a) is a newly recognized risk factor of heart disease. Lp(a) is a type of LDL which is particularly atherogenic (causes cholesterol deposits in arteries) and also appears to increase the risk of blood clot formation in already narrowed arteries leading to heart attacks or strokes. Lp (a) is dependent on genetic factors and hence levels are often found to be elevated in families with a history of early heart disease. A normal Lp (a) level is about 15 mg/dl. Heart disease risk increases with levels above 30 mg/dl. The only effective medication for Lp (a) is Niacin, but the risk associated with Lp (a) decreases if LDL-cholesterol is lowered by diet or other medications. Lp (a) is measured in specialized laboratories.

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