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
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
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.