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

HDL cholesterol is what many people call good cholesterol. It takes extra cholesterol out of your artery walls and carries it back to your liver. A low level is a signal worth understanding, and it often comes with high triglycerides and too little exercise.

Why we test it

HDL makes the opposite trip to LDL. LDL carries cholesterol out to your tissues and, if it stays high for years, leaves it in your arteries. HDL brings some of it back to your liver.

A low HDL is linked to a higher risk for your heart. And it rarely comes alone: high triglycerides, fat around the belly and a body that struggles to use sugar often come with it.

You cannot feel any of this: only a blood test shows it.

What it tells you, and what it does not

If it is low, it usually says something about your habits or your metabolism: too little exercise, smoking, a few extra kilos around the belly. Sometimes it runs in the family.

But HDL is a signal, not a goal in itself. In studies, raising it with a drug did not protect the heart: what counts is removing what pushes it down.

And a very high HDL does not mean better protected arteries. For heart risk, LDL and ApoB matter more.

That is why it is read together with other tests:

Normal HDL cholesterol levels by age and sex

For HDL the lab only sets a lower limit: below it, the result is marked low. On some reports the limit is 35 mg/dL for everyone.

Many labs, though, use a higher limit for women, and sometimes for men too. The one printed on your own report is the one that counts: if it marks your result low, go by your report.

In adults the limit usually does not change with age. It differs more between women and men: women usually have higher HDL.

In the Rosa report you also see your optimal range, which differs for women and men, and your HDL read together with your other blood fats.

What your result means

Find the row for your result, in mg/dL. A low HDL is not an immediate danger: it matters for your heart over the years. A result below 8, which is very rare, should always be seen by a doctor.

If your HDL is low or high

High HDL cholesterol: is higher always better?

No. Up to a point, a higher HDL is linked to a lower risk for your heart. Beyond that, it does not protect you more: in studies, very high levels were sometimes linked to more health problems, not fewer.

A very high HDL can come from your genes or from alcohol. It causes no symptoms and does not need lowering, but it is no guarantee: LDL, ApoB and triglycerides give the real picture.

There are no foods to avoid. But if you drink often, drinking less is good for you, even if your HDL drops a little.

What can skew the result

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

When to worry

Talk to a doctor if:

With Rosa, an HDL below 8 is always flagged to a doctor. It is a very rare result.

Frequently asked questions

What is the LDL to HDL ratio? It is your LDL cholesterol divided by your HDL, and usually the lower it is, the better. It is read like the total to HDL ratio: your doctor looks at it with ApoB, blood pressure and smoking.

Do normal values change with age? In adults the limit on your report usually does not. It differs more between women and men: women usually have higher HDL, and many labs use a higher limit for them. Children and teenagers have different reference values.

Do I need to fast for an HDL cholesterol test? For HDL 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.

Is HDL cholesterol calculated? No, it is measured in your blood. It is LDL that is often calculated, from total cholesterol, HDL and triglycerides.

How often should it be checked? For people who feel well there is no fixed rule: Rosa measures it twice a year. If it is low and you change your habits, it is usually checked again after about three months.

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