Triglycerides | Pathology Tests Explained

What is being tested?

This test measures the amount of triglycerides in your blood. Triglycerides are the body's storage form for fat. Most triglycerides are found in adipose (fat) tissue. Some triglycerides circulate in the blood to provide fuel for muscles to work. Extra triglycerides are found in the blood after eating a meal — when fat is being sent from the gut to adipose tissue for storage. Ideally, the test for triglycerides should be done when you are fasting and no extra triglycerides from a recent meal are present. During fasting most triglycerides are carried in the blood by lipoproteins called very low density lipoproteins (VLDL).

How is it used?

Blood tests for triglycerides are usually part of a lipid profile used to identify the risk of developing heart disease.

Results of the cholesterol test and other components of the lipid profile are used along with other known risk factors of heart disease to develop a plan of treatment and follow-up. Treatment options may include lifestyle changes, such as diet or exercise programs, or lipid-lowering drugs, such as statins. Australian guidelines recommend a treatment target of <2.0 mmol/L for triglycerides.

If you are diabetic, it is especially important to have triglycerides measured as part of any lipid testing since diabetics tend to have high triglycerides.

Having high triglycerides can also lead to a serious medical condition called pancreatitis which is inflammation of the pancreas gland.

When is it requested?

Lipid profiles, including triglycerides, are recommended as routine tests to evaluate risk of heart disease. High levels of triglycerides in the blood are associated with an increased risk of developing cardiovascular disease (CVD). The treatment target of triglyceride is <2mmol/L. If the triglyceride levels remain elevated after lowering LDL cholesterol, further medications and acions to lower triglyceride may be considered.

What does the result mean?

If you have a high fasting triglyceride level, your doctor may wish to find out whether you have a high fat diet, or high sugar diet, a high intake of alcohol or have diabetes or hypothyroidism. It is unusual to have high triglycerides without also having high cholesterol. Having high lipids may increase your risk of developing heart disease and you may be given treatment aimed at lowering your lipid levels. The type of treatment used may differ depending on whether cholesterol, triglycerides, or both are high. Australian guidelines recommend treatment target of <2.0 mmol/L for triglycerides.

When triglycerides are very high (e.g. at least 10-15 mmol/L), there is a risk of developing pancreatitis (inflammation of the pancreas).

Reading your results

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.

Comment: LDL-Cholesterol greater than or equal to 6.4 mmol/L:
Familial hypercholesterolaemia, an autosomal dominant cause of premature cardiovascular disease is highly likely (risk greater than 1 in 2).
Recommend The Atherosclerosis Society calculator to calculate diagnostic score and information page to assist with diagnosis and management, if required.

Understanding what is in your 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.

Is there anything else I should know?

Testing should be done when you are fasting. For 9 to 12 hours before the test, only water is permitted.

If you are diabetic and your blood sugar is out of control, triglycerides may be very high.

Triglycerides may change dramatically in response to meals. Very high values are seen after a meal. Even fasting levels vary considerably day to day. Therefore modest changes in fasting triglycerides measured on different days are not considered to be abnormal.

Certain drugs such as corticosteroids, protease inhibitors for HIV, beta blockers, and oestrogens can increase blood triglyceride levels.

There is increasing interest in measuring triglycerides in people who have not fasted. The reason is that a non-fasting sample may be more representative of the "usual" circulating level of triglyceride since most of the day blood lipid levels reflect post-meal (post-prandial) levels rather than fasting levels. However, it is not yet certain how to interpret non-fasting levels for evaluating risk so, at present, there is no change in the current recommendations for fasting prior to tests for lipid levels.

Common questions

What type of diet is best for optimal triglyceride levels?

Since triglycerides are circulating forms of fat, you might think that a high fat diet will raise triglycerides and a low fat diet would lower triglycerides. However, carbohydrate is also a very important dietary predictor of triglycerides. Diets high in carbohydrates, especially sugar, lead to increases in triglycerides. Australian guidelines recommend treatment target of <2.0 mmol/L for triglycerides.

What drug treatments are recommended for uncontrolled triglyceride levels?

For many people, uncontrolled triglycerides are caused by disorders such as diabetes, obesity, kidney failure, or alcoholism. Therefore the treatment strategy is to treat the primary cause. When high triglycerides are not caused by another disorder, they are often seen together with high cholesterol. Treatment is directed toward lowering both cholesterol and triglycerides. If diet fails, drug treatment is generally recommended. If triglyceride levels remain elevated, treatment with one of the following may be considered; fenofibrate, nicotinic acid or fish oil.

Can exercise help with triglyceride levels?

Yes. Exercise is especially helpful in lowering triglycerides and raising HDL (which tends to decrease when triglycerides increase). Even in the absence of weight loss, exercise will help you lower both LDL cholesterol and triglycerides, while raising HDL cholesterol.