HDL cholesterol: what the test measures, normal levels for men and women, and what low or high HDL means

HDL cholesterol (HDL-C) is the amount of cholesterol carried inside high-density lipoprotein particles, the smallest and densest of the lipoproteins. HDL particles pick up cholesterol from peripheral tissues, including the macrophages inside arterial plaque, and carry it back to the liver for excretion in bile — a process called reverse cholesterol transport. They also carry anti-inflammatory and antioxidant proteins.

On a lipid panel HDL-C is measured directly after the other lipoproteins are precipitated or blocked, so it is not affected by triglycerides or by fasting the way calculated LDL is. It is reported in milligrams per deciliter in the United States and millimoles per liter elsewhere (divide by about 38.7 to convert).

The number counts cholesterol, not particles or function. Research over the past decade has shown that how well HDL particles remove cholesterol — their efflux capacity — predicts risk better than the amount of cholesterol they carry, and that very high HDL-C does not mean very efficient HDL. HDL-C remains the measure on routine panels because it is cheap, standardized and well validated as a population risk marker.

HDL is part of every lipid panel, so it is checked whenever cholesterol is: a first panel in young adulthood, every four to six years at low risk, and more often with high blood pressure, diabetes, obesity, smoking, kidney disease or a family history of early heart disease. It is included in the ten-year cardiovascular risk calculation, where a low HDL raises the estimated risk and a high one lowers it.

A low HDL is one of the five criteria of metabolic syndrome, alongside high triglycerides, a large waist, high blood pressure and high fasting glucose, so people with any of those are tested to see whether the pattern is present. Women entering menopause, people who have stopped exercising or gained weight, and anyone starting hormone, steroid or beta-blocker treatment also benefit from a repeat panel.

HDL comes on the standard lipid panel with total cholesterol, LDL and triglycerides, which a doctor can order or you can order online through TestWell for a draw at a Quest or Labcorp patient service center; a licensed physician reviews the order and results post to your portal within one to three business days against sex-specific bands. Advanced panels add HDL particle number and size, which help when HDL-C and risk seem to disagree.

HDL-C itself does not require fasting, but the panel it comes on is usually drawn fasting for the triglycerides and calculated LDL; nine to twelve hours with water is standard. Avoid heavy alcohol for a day or two beforehand — alcohol raises HDL transiently — and avoid unusually intense exercise the day before. Acute illness lowers HDL for weeks, so wait until well.

Tell the ordering physician about estrogen, testosterone and anabolic steroid use, beta-blockers, progestins, thiazides and retinoids, and about smoking, since each shifts HDL in a known direction and changes how the result is read.

Women run higher HDL than men throughout adult life, largely through estrogen, so the cutoffs differ: an HDL below 40 milligrams per deciliter is low for men and below 50 is low for women. Sixty and above has traditionally been called protective and counts as a negative risk factor in the older risk scoring systems. Most people fall between 40 and 60.

The relationship is not linear at the top. Large population studies have found that very high HDL — roughly above 90 in men and 100 to 110 in women — is not associated with lower mortality and in some cohorts with slightly higher, probably because some of these very high values reflect dysfunctional HDL or genetic variants rather than vigorous reverse cholesterol transport. A very high HDL is therefore no longer read as a license to ignore LDL.

Units matter when comparing reports: 40 milligrams per deciliter is about 1.0 millimoles per liter and 60 is about 1.55. Pregnancy raises HDL by 10 to 20 percent in the second trimester.

Low HDL rarely occurs alone. Its usual companions are high triglycerides, abdominal weight gain, physical inactivity, insulin resistance or type 2 diabetes, and smoking — the cluster called metabolic syndrome, in which the liver's handling of triglyceride-rich particles pulls cholesterol out of HDL. A diet very high in refined carbohydrate lowers HDL the same way. Low HDL is also more common in men, in South Asian populations, and with anabolic steroids, progestins, some beta-blockers and thiazides.

Less common causes include chronic kidney disease, liver disease, chronic inflammation, and rare genetic disorders of HDL production (such as ApoA-I deficiency or Tangier disease), in which HDL is nearly absent. Acute illness, surgery and infection lower HDL temporarily.

Low HDL has no symptoms of its own; it is a risk marker found on a panel. The question it raises is about the whole metabolic picture — triglycerides, glucose or A1c, blood pressure, waist — because treating that picture (weight loss, aerobic exercise, stopping smoking, fewer refined carbohydrates) is what raises HDL and lowers risk. Niacin and CETP inhibitors raise HDL substantially but did not reduce heart attacks in trials, so HDL is no longer a drug target in itself; LDL and ApoB remain the levers.

HDL between 60 and about 90 generally reflects regular aerobic exercise, a healthy weight, moderate alcohol intake, estrogen, or favorable genetics, and is associated with lower heart risk in most studies. It still does not cancel a high LDL: the two numbers are read together, and the LDL goal is set by overall risk whatever the HDL.

Very high HDL — above about 90 in men and 100 in women — can come from heavy alcohol use, certain medications (estrogen, some anticonvulsants, corticosteroids), an overactive thyroid, primary biliary cholangitis, or inherited variants such as CETP deficiency that leave HDL large and cholesterol-rich but not necessarily functional. In these cases the HDL number is high without the usual benefit, which is why guidelines stopped treating a very high HDL as protective and why ApoB and LDL carry the decision.

The ratio of triglycerides to HDL, read from a fasting panel, is a quick marker of insulin resistance — values above about 3 in milligram units suggest the small, dense LDL pattern that accompanies metabolic syndrome. Total cholesterol divided by HDL, once a common risk index, has largely given way to non-HDL cholesterol and ApoB, which count the atherogenic particles directly.

For most people the useful next test after a low HDL is not an HDL subfraction panel but a fasting glucose or A1c, a blood pressure reading and a waist measurement, because those define metabolic syndrome and its treatment. Advanced lipid testing — HDL particle number, ApoB, Lp(a) — is reserved for people whose standard panel does not explain their risk or whose LDL is near a treatment threshold.