How is it used?
The test for LDL cholesterol is used to predict your risk of developing heart disease and stroke. Results of the LDL cholesterol test and other components of the lipid profile are considered along with other known risk factors of heart disease to develop a plan of treatment and follow-up. Accordingly certain high risk people qualify for PBS subsidised drugs.
Treatment options may include lifestyle changes such as diet or exercise programs or lipid-lowering drugs such as statins. The treatment target for LDL cholesterol is <2.0 mmol/L.
When is it requested?
LDL cholesterol levels are ordered as part a lipid profile, along with total cholesterol, HDL cholesterol (HDL-C), and triglycerides. This profile may be used as a screening test in a healthy person as part of a routine physical examination, for Aboriginal and Torres Strait Islander adults aged 35 years and over and otherwise adults aged 45 years and over. Then they should be assessed regularly depending on the risk. A lipid profile may be requested on someone who has had a high screening cholesterol to see if the total cholesterol is elevated because of too much LDL-C and on those who have one or more major risk factors for heart disease. LDL-C may also be requested at regular intervals to evaluate the success of lipid-lowering lifestyle changes such as diet and exercise or to determine the effectiveness of drug therapy such as .
In illnesses like acute coronary syndrome (acute phase response) plasma triglyceride, and very low density lipoprotein (VLDL) levels increase, while high density lipoprotein (HDL), low density lipoprotein (LDL) and total cholesterol levels decrease. Therefore lipid levels should be checked away from acute illness.
Adults taking statins may have a fasting lipid profile done 4 to 12 weeks after starting therapy and then every 3 to 12 months thereafter to assure that the drug is working.
What does the test result mean?
Elevated levels of LDL-C indicate risk for heart disease and stroke. In Australia treatment (with diet, exercise and drugs) for people with high CVD risk, aims to lower LDL-C to a target value of less than 2.0 mmol/L. This is especially important if you have other risk factors for heart disease. Risk factors include cigarette smoking, hypertension, low HDL-C (< 1 mmol/L), family history, being overweight, microalbuminuria and/or renal impairment, diabetes, impaired fasting glucose or glucose intolerance and over the age of 45 years. PBS Eligibility Criteria For Cholesterol Lowering Medicines are based on different lipid levels and other risk factors.
Those with low-density lipoprotein cholesterol (LDL-C) >4.0 or total cholesterol >7.5 should be reviewed for family history and clinical features of Familial Hypercholesterolaemia.
If lipid levels are abnormal, a second confirmatory sample should be taken on a separate occasion (as levels may vary between tests) before a definitive diagnosis is made.
Is there anything else I should know?
Measurement of LDL-C generally requires an 8 - 12 hour fast — meaning that you must not eat or drink anything that has calories for 12 hours before your blood is drawn. You may drink water. This is because LDL-C is usually calculated from the results of other tests, including triglycerides, that require fasting. This result may be reported as 'calculated LDL-C'. Some laboratories can measure LDL-C directly using a special technology and fasting is not necessary. This test is usually called 'direct LDL-C'.
LDL cholesterol should be measured when a person is healthy. LDL cholesterol is temporarily low during acute illness, immediately following a heart attack, or during stress (like from surgery or an accident). You should wait at least six weeks after any illness to have LDL cholesterol measured.
In women, cholesterol is high during pregnancy. Women should wait at least six weeks after the baby is born to have LDL cholesterol measured.
Familial hypercholesterolaemia (FH) is a severe form of elevated cholesterol levels that runs in families. It is often undetected until damage is done and the person develops cardiovascular disease. It can be easily screened for and treated early in life. Information about FH can be found at the FH Australia network site. Individual risk of having FH can be determined using this online calculator or using this form.