HDL Cholesterol

HDL is high-density lipoprotein, the class of blood particle that carries cholesterol out of your artery walls and back to the liver for disposal. Because people with more of it tend to have fewer heart attacks, it picked up the nickname 'good cholesterol.' The nickname flatters it. HDL reports your risk without controlling it. Every drug built to raise HDL has failed to prevent heart attacks, and past a point, more HDL stops helping.

What is HDL cholesterol?

Cholesterol does not dissolve in blood, so it rides inside particles wrapped in protein. HDL, high-density lipoprotein, is the particle type that picks up excess cholesterol from tissues and artery walls and ferries it back to the liver, a process called reverse cholesterol transport. LDL, low-density lipoprotein, does the opposite, delivering cholesterol into the wall where it can build up. That tidy 'takes cholesterol away' story is why HDL got the halo. The biology is messier than the label.

What is a good HDL level?

On a US lipid panel HDL is reported in milligrams per deciliter (mg/dL). The cutoffs are sex-specific because women run higher on average.

Those cutoffs come from the National Cholesterol Education Program and the 2018 AHA/ACC cholesterol guideline ¹²; the caution about very high HDL comes from a large Danish cohort ⁵.

What does low HDL mean?

A low HDL, under 40 mg/dL in men or under 50 in women, counts as a cardiovascular risk factor on its own ¹. What makes it useful is the company it keeps. A low HDL rarely shows up alone; it usually rides with high triglycerides, the fat your blood carries after meals, and with insulin resistance, where your cells respond sluggishly to insulin so your body pumps out more of it. That cluster is the early metabolic picture that can later become high cholesterol and type 2 diabetes.

This is why the triglyceride-to-HDL ratio does more work than HDL by itself. A high ratio flags insulin resistance and a shift toward small, dense LDL particles (the more artery-damaging kind). The triglycerides page owns that ratio and its thresholds; the short version is that a low HDL is worth reading next to your triglyceride number, not in isolation.

Enter your triglycerides and HDL below to see your ratio and where it sits.

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Your cholesterol ratios, in context

Two ratios that say more than any single number. Nothing leaves your browser.

Total cholesterolmg/dLHDL-Cmg/dLTriglyceridesmg/dL

Enter all three numbers to see your ratios.

Educational, not a diagnosis. TG/HDL thresholds are population-dependent and a surrogate for insulin resistance, not a diagnosis of it. Bands describe the values, not you.

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Is HDL really 'good' cholesterol you should try to maximize?

The association is real. Across large populations, higher HDL goes with fewer heart attacks. The problem is what happens when you try to act on it. If HDL were doing the protecting, then raising it should lower risk, and nudging it up with genes or drugs should help. Neither pans out.

Geneticists tested it with Mendelian randomization, a method that uses inherited gene variants as a natural experiment: people born with HDL-raising variants should be protected if HDL itself causes the benefit. In a 2012 analysis in the Lancet, they were not ³.

These data challenge the concept that raising of plasma HDL cholesterol will uniformly translate into reductions in risk of myocardial infarction.Voight et al., Lancet, 2012

Drug trials told the same story. Niacin (vitamin B3 at high doses) raises HDL, but adding it to a statin did not cut cardiovascular events in the HPS2-THRIVE trial, which also caused more serious side effects ⁴. Drugs engineered specifically to raise HDL, including the CETP inhibitors, followed the same pattern: they lifted HDL and still did not prevent heart attacks. Contrast LDL, where lowering the number consistently lowers heart-attack risk across trials.

Can HDL be too high?

Yes, in the sense that more is not simply better. A large Danish cohort found a U-shaped relationship between HDL and death from any cause: risk was lowest in the middle and higher at both ends ⁵. Men with HDL around 97 to 115 mg/dL had markedly higher all-cause mortality than men in the 54 to 77 mg/dL range. This is chiefly a finding in men; in women the excess mortality appears only at much higher HDL, around 135 mg/dL and above, so a level in the 80s or 90s sits near the healthy middle for a woman.

The extremes are uncommon and usually genetic. A high HDL is not something to treat, and a number above the reference range is not a bonus to aim for. If yours sits very high, there is nothing to fix, but mention it to your clinician so it is noted alongside your other numbers.

The three lipid numbers answer three different questions

The 'good and bad cholesterol' shorthand hides that HDL, LDL, and triglycerides each report something different, and only some of them are levers you can pull.

Of the three, LDL is the one guidelines lower ². HDL sits alongside it as context, and the how to read your lipid panel guide walks through how the numbers fit together.

How do you raise HDL cholesterol?

The moves that raise HDL are worth doing for other reasons, and the HDL bump is a side effect. Regular aerobic exercise, losing excess weight, and quitting smoking each nudge HDL up, and they improve the whole risk picture more than they move HDL. Cutting refined carbohydrates and alcohol tends to lower triglycerides and lift HDL together.

How HDL is tested and how often

HDL is not a separate order; it comes as part of the standard lipid panel alongside total cholesterol, LDL, and triglycerides, usually a routine, low-cost blood test covered by insurance for screening. You do not have to fast for it: non-fasting samples are fine for a lipid profile for most people ⁶. For how often to screen and when to check family members, see how to read your lipid panel. For how HDL fits into your overall heart risk, step back to the heart health hub.