Hypercholesterolemia or raised blood cholesterol is a risk factor for cardiovascular events such as stroke or heart attack. Individuals with hypercholesterolemia are therefore advised to adopt lifestyle changes such as a healthy, balanced diet and regular exercise, to lower their risk of adverse health events.
A diagnosis of hypercholesterolemia is based on routine blood analysis to check levels of “bad” cholesterol, which includes triglycerides and low-density lipoproteins (LDLs). The blood is also checked for the presence of high-density lipoprotein (HDLs) or “good” cholesterol. The risk of cardiovascular disease is increased if the LDL or triglyceride level is raised or if the HDL level is lower than usual.
A patient is usually asked not to eat for at least 10 to 12 hours before the blood sample is taken, because undigested food can interfere with the outcome of the test.
The results of the blood tests are used to assess the patient’s risk of cardiovascular disease. Whether this risk is low, moderate or high is calculated based on the blood test results as well as other factors such as body mass index (BMI), age, gender, ethnicity and the presence of any modifiable risk factors such as high blood pressure or diabetes.
Governmental guidelines recommend that the total cholesterol level should be 5 mmol/L or less among healthy adults and 4 mmol/L or less among those at a high risk of cardiovascular disease. For LDL specifically, the blood level should be 3mmol/L or less in healthy adults and 2 mmol/L or less among those at high risk of cardiovascular disease. The HDL level should ideally be above 1 mmol/L.
Another measurement that is used to assess cardiovascular risk is the ratio of total cholesterol to HDL, which should be below 4.
The triglyceride level may also be assessed because an excess of these lipids can also increase the risk of cardiovascular problems. Ideally, the triglyceride level should be less than 1.7 mmol/L.
Reviewed by Sally Robertson, BSc