At a glance

Also known as

LDL; LDL-C; 'bad' cholesterol

Why get tested?

To determine risk of developing heart disease and stroke

When to get tested?

Screening 

  • As part of a health examination with a lipid profile; every four to six years in adults with no risk factors for heart disease 
  • Adults aged 45 years and over without known history of CVD
  • Aboriginal and Torres Strait Islander adults aged 35 years and over without known history of CVD
  • The upper age limit of 74 years is generally accepted

Monitoring  

  • May be done more frequently and at regular intervals when risk factors for heart disease are present, when prior results showed high risk levels, and/or when undergoing treatment for unhealthy lipid levels
Sample required?

A blood sample drawn from a vein in the arm or from a fingerprick (capillary).
Measurement of LDL cholesterol generally requires an 8-12 hour fast before the sample is taken. Only water is permitted.

What is being tested?

LDL is a type of lipoprotein that carries cholesterol in the blood. LDL cholesterol (LDL-C) is considered to be undesirable because it deposits excess cholesterol in the walls of blood vessels and contributes to 'narrowing of the arteries' and heart disease and strokes. Hence LDL cholesterol is often termed 'bad' cholesterol. The test for LDL cholesterol measures the amount of cholesterol bound to LDL in blood. 

LDL-C is usually not measured directly, but calculated using an equation which uses the other components of the lipid profile. Occasionally LDL-C can be measured directly.
 

How is the sample collected for testing?

The test for LDL cholesterol uses a blood sample. Most often, the blood sample is collected by venipuncture (using a needle to collect blood from a vein in the arm). Occasionally a fingerprick test can be used. Measurement of LDL cholesterol generally requires an 8-12 hour fast before the sample is taken.

The Test

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 statins

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.
 

Reading your results

Lipid Profile – cholesterol (total, HDL and LDL) & triglycerides
The lipid profile is a group of tests used to assess your risk of cardiovascular diseases (heart disease, stroke and related diseases). It checks total cholesterol, triglycerides, HDL cholesterol and LDL cholesterol. The results are considered along with other important factors such as your age, gender, ethnicity and blood pressure and whether you have diabetes or smoke.
 
If you’ve had test results for cholesterol and triglycerides, this example form may help you understand them.
 
It is important to realise that the format and look of reports often differ between laboratories so your results form may not look exactly like this.
 
  *Requesting Doctor   *Patient    
Name: Michael Smith   Paul Harding    
Address: Rodwell Medical Centre, 12 Main Street, Rodwell NSW   58 Bramble Street, Rodwell NSW    
Date of birth:     12-Nov-1990    
Sex:     Male    
           
*Date of report: 28-Feb-19 16-Mar-19
      Latest results *Reference Interval *Units
*Collection date: 28-Feb-19 16-Mar-19    
*Collection Time: 8:30 9:00    
*Request No: 123456 345678    
Test names          
Biochemistry
Cholesterol 9.0 H 9.1 H ≤5.2 mmol/L
Triglycerides 1.2 1.5 ≤ 2.5 mmol/L
HDL Cholesterol 1.1 1.2 1.00-2.50 mmol/L
LDL Cholesterol 7.4 H 7.2 H ≤ 3.5 mmol/L
Comment: LDL-Cholesterol ≥ 6.4 mmol/L:
Familial hypercholesterolaemia, an autosomal dominant cause of premature cardiovascular disease is highly likely (risk greater than I in 2).
Recommend http://www.athero.org.au/calculator to calculate diagnostic score and http://www. athero.org.au/fh/health-professionals/what-is-familial-hypercholesterolaemia-fh/ to assist with diagnosis and management, if required.

Who prepares your test results report?

In this report, four tests have been performed as a group. They each measure a different substance in the blood that can indicate a possible health problem if levels are shown to be too high or too low.
 
In this example case, the purpose of the first test was to check the lipid profile (cholesterol, triglycerides plus HDL and LDL) of this relatively young man.  Normally, this would not be done unless the person has known risk factors. In this case, Paul has a strong family history of early heart disease. His grandfather and two uncles have all died some years ago from heart attacks and recently, his 53-year old father has also had a fatal heart attack. His father had always been apparently healthy and had not had blood tests to check his lipids.   
 
What the results mean?
Two sets of results are shown from tests that have been performed just over two weeks apart.
 
  • In the first column of results, showing tests performed on the 28th of February Paul was found to have very high total cholesterol and LDL cholesterol.
  • The current results (16th March) have been done to confirm the initial results because they were so abnormal and because Paul had been drinking quite heavily prior to the first test. The second set of results are very similar to the first and have not changed after two weeks without alcohol.
  • The comment on the report states that Paul has a high probability of having familial hypercholesterolaemia. This is an inherited condition in which people have a very high risk of developing early coronary artery disease. They need to have treatment.
  • The results have been compared to a reference interval. This is shown on the far right (column 5).
  • The reference intervals represent the levels of cholesterol and triglycerides which would be considered ‘healthy’ for the general population.  (Note that for these two substances, the range given is not the same as most ‘normal’ ranges which are derived from the results for most healthy people. In this case they are derived from studies showing the levels at which the risk of developing early coronary artery or other atherosclerotic disease is acceptably low. Because our modern diet and lifestyle are not ideal, the statistical ‘normal’ ranges would be higher than is desirable.)
  • If your results are outside this range and flagged with an H (high) or L (low) this is just to draw your attention to them. If the total cholesterol, LDL cholesterol or triglyceride levels are flagged as high this suggests that you and your doctor should discuss strategies to reduce the levels.
  • Your results need to be interpreted by your doctor who will consider them in the context of your whole medical history, as well as the results of any other investigations you have had.
  • There are a number of other causes of high cholesterol results and also high triglyceride results. You should also look at the entry for lipid profile.
 
Who prepares your test results report?
 
Your tests will have been performed by scientists and/or pathologists (who are medical doctors).  The pathologist-in-charge who specialises in interpreting test results and observing and evaluating biological changes to make a diagnosis, will be responsible for your report. The pathologist is also available to discuss your results with your doctor.



 

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. 
 

About Reference Intervals

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.
 

Common Questions

What treatments are recommended for high LDL cholesterol levels?

The first step in treating high LDL-C is adoption of lifestyle changes, including decreasing the amount of saturated fat in the diet, achieving and maintaining desirable body weight, and getting regular exercise.  If lifestyle changes do not adequately lower LDL-C, drugs such as statins may be prescribed. For people with certain combinations of risk factors and LDL-C levels, drug therapy may be prescribed in concert with lifestyle changes.
 

How much will LDL cholesterol change as a result of lifestyle changes, like exercise or diet?

Adoption of a diet low in saturated fat (less than 6% of calories from saturated fat) will usually lower LDL cholesterol by about 10%.

Should someone with a family history of high LDL cholesterol levels be tested at a young age?

Often, children who have a family history of high LDL cholesterol and heart disease are screened for total cholesterol and LDL cholesterol at a young age. 

Children with Familial Hypercholesterolaemia (FH) are unlikely to respond to dietary modification alone. Therefore they are likely to require statin therapy initiated along with lifestyle modifications. Although data on long-term statin use in adults suggest a safe profile, the long-term safety of statin therapy initiated in childhood is uncertain. Side effects with statins are rare and include myopathy, new-onset type 2 diabetes mellitus, and hepatic enzyme elevation. 
 


Last Review Date: November 7, 2017