Total cholesterol: what it is, what it tells you and why we test it

Total cholesterol is the sum of all the cholesterol in your blood. It includes LDL, called bad cholesterol, HDL, called good cholesterol, and a share tied to triglycerides. That is why on its own it says little: two people with the same total can carry very different risks.

Why we test it

Total cholesterol is the first number in the blood fat test, and almost every lab report shows it. Following it over the years shows whether something is changing.

A very high number can point to inherited high cholesterol. It pays to find out early, because it often affects others in the family too.

Your risk for your heart and arteries, though, is better told by LDL, HDL, triglycerides and ApoB. That is why the Rosa report shows it next to them.

What it tells you, and what it does not

The total adds up parts that pull in opposite directions. LDL carries cholesterol out to your tissues and, if it stays high, leaves it in your arteries; HDL takes some of it back to your liver.

So a high total can mean a high LDL, but also a high HDL, which is usually not a problem.

And a normal total does not show on its own that all is well: if your HDL is low, your LDL or ApoB can still be high.

That is why it is read together with other tests:

• LDL cholesterol: The part that can build up in your arteries
• HDL cholesterol: The part that goes back to your liver
• Triglycerides: Part of the total travels with them
• ApoB: Counts the particles that can build up in your arteries

Normal total cholesterol levels

The lab decides what is normal. A typical range is 120 to 240 mg/dL, and your own report may print different limits.

Next to the range, some lab reports also print a lower desirable value, for example below 180 mg/dL. Above it, look more closely at your LDL and HDL.

In adults the limit is the same for women and men, and it does not change with age.

In the Rosa report you also see your optimal range, with total cholesterol read together with LDL, HDL and triglycerides.

What your result means

Find the row for your result, in mg/dL. Which values should a doctor see? From 310 up: it can be inherited high cholesterol.

• Below 120: Low. Cholesterol medicines are often behind it, sometimes an overactive thyroid. Read it with your LDL and HDL. If you do not know why it is low, talk to your doctor.
• 120 to 200: Normal. Inside the range on a typical lab report, though some print a lower desirable value. On its own it is not enough: check your LDL and HDL too. In the Rosa report you also see whether you are in your optimal range.
• Above 200, up to 240: Near the limit. Inside the range on a typical lab report, but above the desirable value some print next to it. What matters is whether LDL or HDL is pushing it up. In the Rosa report, from here your plan suggests what to change in your diet.
• Above 240, below 310: High. Above your report’s limit. LDL and diet are usually behind it, sometimes a high HDL. Check whether LDL or HDL is behind it, and talk to your doctor. If it is LDL, start with what you eat.
• 310 and above: Very high. It can be inherited high cholesterol, called familial hypercholesterolaemia. Talk to your doctor: the family is usually checked too.

If your total cholesterol is high or low

• High total cholesterol: LDL, diet or genes are often behind it. Sometimes it is a high HDL: if your LDL is fine, that is usually not a problem.
• Low total cholesterol: Read it together with LDL and HDL. Cholesterol medicines are often behind it, sometimes an overactive thyroid.

Total cholesterol and HDL: the ratio

You get the ratio by dividing your total cholesterol by your HDL, both in the same unit. The lower it is, the better: it means a bigger share of the total is good cholesterol.

That is why it says more than the total alone. In a large analysis of dozens of studies, the ratio predicted the risk of dying from heart disease much better than the total did.

Some lab reports already print it, sometimes called the cardiovascular risk index. It is still an estimate: your doctor also looks at LDL, ApoB, blood pressure, smoking and family history.

What can skew the result

A few things change the number for a while. It helps to know them before you read it.

• A lot of saturated fat: A spell of eating a lot of butter, cheese and fatty meat can push it up. The habit counts, not a single meal.
• Less movement than usual: A spell of moving less than usual can push it up.
• Omega-3 supplements: Those rich in DHA, a type of omega-3, can raise it a little. Tell your doctor.
• Pregnancy: In pregnancy all blood fats rise, and that is normal. Read the number with your obstetrician.

When to worry

Talk to your doctor if:

• Your total cholesterol is 310 or more.
• It is high and your LDL or ApoB is high too.
• Someone in your family had a heart attack or stroke at a young age.
• Your ApoB and lipoprotein(a) are both high.
• You have chest pain or pressure: call 112 or go to the emergency department.

With Rosa, a total cholesterol of 310 or more is always flagged to a doctor.

Frequently asked questions

What are normal total cholesterol levels by age? In adults the limit on your report is the same at every age, for women and men. Over the years, though, cholesterol tends to rise, in women especially after menopause. Children and teenagers have different reference values.

Total cholesterol at 240: what should I do? It is the upper limit of a typical lab report, not an emergency. Check whether LDL or HDL is pushing it up and talk to your doctor. If it is LDL, start with what you eat and repeat the test after about three months.

How is total cholesterol calculated? It is not calculated: the lab measures it in your blood. The formula you find online, LDL plus HDL plus a fifth of triglycerides, is the LDL calculation run backwards. It is the lab that starts from the total to estimate LDL.

Do I need to fast for a total cholesterol test? For the total itself, no: a meal changes it very little. But it is measured together with triglycerides, which rise after a meal, so it is best to arrive fasted. You can drink water.

How often should it be checked? For people who feel well there is no fixed rule: Rosa measures it twice a year. After a change in diet, it is usually checked again after about three months.

Sources

• Nordestgaard and colleagues, familial hypercholesterolaemia is underdiagnosed and undertreated in the general population: guidance for clinicians. European Heart Journal, 2013. PMID 23956253
• Prospective Studies Collaboration (Lewington and colleagues), blood cholesterol and vascular mortality by age, sex and blood pressure: a meta-analysis of individual data from dozens of studies. Lancet, 2007. PMID 18061058
• Nordestgaard and colleagues, fasting is not routinely required for a lipid profile: a joint consensus statement from EAS and EFLM. European Heart Journal, 2016. PMID 27122601
• Friedewald and colleagues, estimating LDL cholesterol without measuring it directly. Clinical Chemistry, 1972. PMID 4337382
• Mach and colleagues, ESC/EAS guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. European Heart Journal, 2020. PMID 31504418