Understanding results: cholesterol tests

Cholesterol has a bad reputation it only partly deserves. Your body needs it — it goes into cell membranes and hormone production, and you would be in trouble without it.²

The problem is quantity and type. When there is too much of the wrong sort circulating, it can build up in artery walls over years, narrowing them and raising the risk of a heart attack or stroke.¹ High cholesterol is common in Australia, affecting a large share of adults, and it produces no symptoms at all.^{3, 4} A blood test is the only way to know where you sit.⁵

What a cholesterol test measures

A standard lipid panel reports four things.

• LDL cholesterol — the "bad" one. It carries cholesterol out to the tissues, and in excess it contributes to plaque building up in artery walls.⁵
• HDL cholesterol — the "good" one. It does the return journey, carrying excess cholesterol back to the liver for disposal.⁵
• Triglycerides — a different kind of fat in the blood. High triglycerides matter more when they appear alongside high LDL or low HDL.⁵
• Total cholesterol — the overall figure, HDL and LDL combined.⁵ It is the number most people know and the least informative of the four, because two people with identical totals can have very different splits underneath.

The guideline targets

Health professionals in Australia work to broad guideline ranges. As a general principle, lower LDL and total cholesterol and higher HDL are better.² The commonly cited targets for most adults are:¹

• Total cholesterol — under 5.5 mmol/L
• LDL cholesterol — under 2.0 mmol/L
• HDL cholesterol — above 1.0 mmol/L
• Triglycerides — under 2.0 mmol/L

These are population-level guides, not personal targets. Someone with existing heart disease or a high overall risk profile is usually advised to aim lower — an LDL below 1.8 mmol/L, for example.¹ Equally, a single number slightly outside a range means little on its own.

What actually matters is the whole picture: your age, blood pressure, smoking status, family history, whether you have diabetes, and how the four lipid measures sit relative to each other. That assessment is a conversation with your doctor, not something to run yourself off a results page.²

What influences your levels

Cholesterol responds to several things, some of which you control and some of which you do not.

Diet plays a part — particularly the balance of saturated and unsaturated fats. Vegetables, fruit, whole grains, fish, legumes, nuts and seeds sit on one side of that ledger; fatty meats, butter, deep-fried food and pastries sit on the other.^{3, 5}

Physical activity is associated with higher HDL, and reducing excess weight is associated with lower LDL and triglycerides.³

Genetics also matter, and this is the part people underestimate. Some people have high cholesterol despite doing everything right, because of an inherited condition such as familial hypercholesterolaemia. Lifestyle changes help, but they do not always resolve it.

Where lifestyle alone is not enough, medication is one of the options your doctor may raise. That is a clinical decision made with someone who knows your full risk profile.³

What a lipid panel won't tell you

• It isn't a heart risk score. Cholesterol is one input into cardiovascular risk assessment, alongside blood pressure, smoking, diabetes, age and family history.
• It doesn't count particles. A standard panel measures the cholesterol carried, not how many particles are carrying it. That is what ApoB measures, and the two can disagree.
• One reading isn't a trend. Lipids move with diet, illness and time of year. A single result is a starting point.
• Normal results aren't a clean bill of health. Plenty of people with unremarkable cholesterol have other risk factors that matter more.

The bottom line

A lipid panel gives you four numbers that are far more useful read together than apart. Total cholesterol on its own tells you very little; the balance between LDL, HDL and triglycerides tells you considerably more.

And because high cholesterol causes no symptoms, testing is genuinely the only way to find out where you stand.