LDL Cholesterol (Low-Density Lipoprotein)

Often called “bad cholesterol,” LDL carries cholesterol to arteries where it can build up and form plaques, increasing heart disease risk.

Last updated: April 10, 2026

LDL cholesterol is often called “bad” cholesterol because high levels contribute to plaque buildup in arteries. An optimal LDL level is below 100 mg/dL — levels above 160 mg/dL are considered high and may significantly increase the risk of cardiovascular disease.

Why Is LDL Cholesterol Tested?

LDL stands for low-density lipoprotein, a type of particle that carries cholesterol through the bloodstream. When there is too much LDL in the blood, it can deposit cholesterol into artery walls, forming fatty plaques in a process called atherosclerosis. Over time, these plaques narrow and harden the arteries, raising the risk of heart attack and stroke.

LDL cholesterol is measured as part of a lipid panel, which also includes total cholesterol, HDL cholesterol, and triglycerides. A healthcare provider may order a lipid panel to:

  • Screen for cardiovascular disease risk during routine checkups
  • Evaluate whether cholesterol levels fall within a healthy range
  • Monitor the effectiveness of cholesterol-lowering medications such as statins
  • Assess overall heart health in people with risk factors like diabetes, high blood pressure, smoking, or family history of heart disease
  • Guide treatment decisions based on individual cardiovascular risk

The American Heart Association recommends that adults aged 20 and older have a lipid panel every 4–6 years, or more frequently for those with elevated risk factors. Children and adolescents may also be screened if there is a strong family history of high cholesterol or early heart disease.

Normal Reference Ranges

LDL cholesterol is typically reported in milligrams per deciliter (mg/dL) in the United States or millimoles per liter (mmol/L) internationally. Ranges may vary by lab, age, sex, and testing method.

Category LDL Level (mg/dL) LDL Level (mmol/L)
Optimal Below 100 Below 2.6
Near-optimal 100 – 129 2.6 – 3.3
Borderline high 130 – 159 3.4 – 4.1
High 160 – 189 4.1 – 4.9
Very high 190 and above 4.9 and above

For high-risk individuals — those with existing heart disease, diabetes, or multiple cardiovascular risk factors — a healthcare provider may recommend an LDL target below 70 mg/dL (1.8 mmol/L). Some guidelines suggest even lower targets for very-high-risk patients.

Note: LDL is most often calculated using the Friedewald equation (Total Cholesterol − HDL − Triglycerides/5) rather than measured directly. Direct LDL testing may be used when triglycerides are very high.

What Does a HIGH LDL Cholesterol Mean?

An elevated LDL level means more cholesterol is circulating in the blood, which increases the risk of plaque forming inside artery walls. The higher the LDL, the greater the likelihood of developing atherosclerosis and cardiovascular events over time.

Common causes of high LDL cholesterol include:

  • Diet high in saturated and trans fats — red meat, full-fat dairy, fried foods, and baked goods
  • Sedentary lifestyle — physical inactivity reduces the body’s ability to regulate cholesterol
  • Obesity — excess body weight, especially around the midsection, is associated with higher LDL
  • Familial hypercholesterolemia — a genetic condition that causes very high LDL from birth
  • Hypothyroidism — an underactive thyroid slows cholesterol metabolism
  • Type 2 diabetes — insulin resistance often worsens LDL levels and particle composition
  • Chronic kidney disease — impaired kidney function can alter lipid metabolism

Less common or temporary causes that may raise LDL include:

  • Certain medications (some diuretics, beta-blockers, corticosteroids, and immunosuppressants)
  • Pregnancy — cholesterol levels naturally rise during pregnancy
  • Smoking — damages blood vessels and can worsen LDL cholesterol levels
  • Liver disease (cholestatic) — can impair cholesterol processing

A slightly elevated LDL (130–159 mg/dL) may be managed through lifestyle changes alone, while significantly elevated levels (160 mg/dL and above), especially combined with other risk factors, often prompt consideration of medication.

What Does a LOW LDL Cholesterol Mean?

A low LDL cholesterol level is generally considered favorable for cardiovascular health. For most people, lower LDL means less cholesterol available to build up in artery walls. However, very low levels (below 40 mg/dL) are uncommon and may occasionally warrant investigation.

Possible reasons for very low LDL include:

  • Hyperthyroidism — an overactive thyroid speeds up cholesterol metabolism, reducing LDL
  • Liver disease — the liver produces cholesterol, and severe liver impairment may reduce production
  • Malnutrition or malabsorption — inadequate fat and nutrient intake can lower cholesterol
  • Certain cancers — some malignancies are associated with unusually low cholesterol levels
  • Genetic conditions — hypobetalipoproteinemia and abetalipoproteinemia cause extremely low LDL
  • High-dose statin therapy — potent cholesterol-lowering medications can bring LDL well below 70 mg/dL

For the vast majority of people, including those on cholesterol-lowering medication, a low LDL is a positive finding. Extremely low levels (below 25 mg/dL) in the absence of medication could suggest an underlying condition worth evaluating.

Factors That Can Affect Your Results

LDL cholesterol results can be influenced by a number of variables beyond underlying health conditions:

  • Fasting status — LDL is usually calculated from a fasting lipid panel (9–12 hours without food). Non-fasting samples may give slightly different results, particularly if triglycerides are elevated
  • Recent illness or infection — acute illness can temporarily lower LDL cholesterol by 10–40%; testing is generally best done when feeling well
  • Weight changes — rapid weight loss can temporarily raise LDL; sustained weight loss typically lowers it
  • Medications — statins, ezetimibe, and PCSK9 inhibitors dramatically lower LDL; some medications like certain birth control pills, beta-blockers, or thiazide diuretics may raise it
  • Pregnancy — LDL cholesterol naturally increases during pregnancy and may remain elevated for several weeks postpartum
  • Age and sex — LDL tends to rise with age; women may see an increase after menopause due to declining estrogen levels
  • Calculation method — when triglycerides exceed 400 mg/dL, the standard Friedewald formula becomes inaccurate, and a direct LDL measurement is needed
  • Time of year — some studies suggest cholesterol levels may be slightly higher in winter months

Should I Be Concerned About My LDL Cholesterol Level?

A single LDL cholesterol reading does not tell the whole story. Cardiovascular risk depends on the full picture — including HDL cholesterol, triglycerides, blood pressure, blood sugar, smoking status, family history, and age. An LDL of 140 mg/dL carries different implications for a 30-year-old with no other risk factors than for a 60-year-old with diabetes and high blood pressure.

Results that may warrant closer attention:

  • LDL of 130–159 mg/dL — borderline high; lifestyle changes are typically the first step, especially with few other risk factors
  • LDL of 160–189 mg/dL — high; a healthcare provider may recommend both lifestyle changes and medication depending on overall risk
  • LDL of 190 mg/dL or above — very high; medication is generally recommended regardless of other risk factors, as this level significantly increases cardiovascular risk
  • LDL above 190 mg/dL in a young adult — may suggest familial hypercholesterolemia, a genetic condition that benefits from early treatment

For people with borderline LDL levels and no other risk factors, there is often no reason for alarm. Simple dietary adjustments and regular physical activity can meaningfully lower LDL over time. A healthcare provider can help determine whether lifestyle changes alone are sufficient or whether medication may be beneficial.

Common Next Steps

Depending on the LDL result and overall cardiovascular risk, a healthcare provider may recommend:

  • Repeat lipid panel — to confirm the result, especially if it is a first-time finding or the reading seems inconsistent
  • 10-year cardiovascular risk assessment — using tools like the ACC/AHA Pooled Cohort Equations to guide treatment decisions
  • Dietary changes — reducing saturated fat, increasing soluble fiber (oats, beans, fruits), adding plant sterols, and choosing heart-healthy fats (olive oil, nuts, fatty fish)
  • Increased physical activity — regular moderate-intensity aerobic exercise, as recommended by a healthcare provider
  • Statin therapy — the most commonly prescribed cholesterol-lowering medication, particularly for those with high LDL or multiple risk factors
  • Additional medications — ezetimibe, PCSK9 inhibitors, or bempedoic acid for patients who need further LDL lowering or cannot tolerate statins
  • Follow-up testing — CRP to assess inflammation, coronary artery calcium scoring, or advanced lipid testing (LDL particle number, apolipoprotein B)
  • Monitoring — repeat lipid panel in 4–12 weeks after starting medication, then every 3–12 months

Frequently Asked Questions

What is a good LDL cholesterol level?

An optimal LDL cholesterol level is below 100 mg/dL for most adults. For those at higher cardiovascular risk, such as people with existing heart disease or diabetes, a target below 70 mg/dL is often recommended. Levels of 100–129 mg/dL are considered near-optimal.

What causes high LDL cholesterol?

High LDL cholesterol may be caused by a diet rich in saturated and trans fats, lack of exercise, obesity, genetics (familial hypercholesterolemia), and certain conditions like hypothyroidism, type 2 diabetes, and kidney disease. Smoking and some medications can also contribute to elevated levels.

Is LDL cholesterol really “bad”?

LDL is called “bad” cholesterol because high levels contribute to plaque buildup in artery walls, a process called atherosclerosis. However, LDL serves a normal biological role in delivering cholesterol to cells that need it. The issue arises when LDL levels remain elevated for extended periods, allowing excess cholesterol to accumulate in arteries.

How can LDL cholesterol be lowered naturally?

Dietary changes can meaningfully lower LDL, including reducing saturated fat intake, increasing soluble fiber (oats, beans, lentils, fruits), and adding foods with plant sterols and stanols. Regular aerobic exercise, maintaining a healthy weight, and quitting smoking also help. These lifestyle changes may reduce LDL by 10–20% in many individuals.

What medications lower LDL cholesterol?

Statins are the most widely prescribed LDL-lowering medications and can reduce LDL by 30–50% or more. Other options include ezetimibe (blocks cholesterol absorption), PCSK9 inhibitors (injectable medications for very high LDL), bempedoic acid, and bile acid sequestrants. A healthcare provider determines the best approach based on individual risk factors and tolerance.

What is the difference between LDL and HDL cholesterol?

LDL (low-density lipoprotein) carries cholesterol to arteries, where it can build up as plaque. HDL (high-density lipoprotein) carries cholesterol away from arteries back to the liver for removal. For this reason, high LDL is a cardiovascular risk factor, while high HDL is generally considered protective. Both are measured together as part of a lipid panel.

Can LDL cholesterol be too low?

For most people, lower LDL levels are associated with lower cardiovascular risk. Very low LDL (below 40 mg/dL) in the absence of cholesterol-lowering medication is uncommon and may be linked to hyperthyroidism, liver disease, malnutrition, or rare genetic conditions. Extremely low levels may warrant further evaluation to rule out an underlying cause.

How often should LDL cholesterol be checked?

Adults aged 20 and older are generally advised to have a lipid panel every 4–6 years. More frequent testing — annually or even more often — may be recommended for people with cardiovascular risk factors, a history of high cholesterol, or those taking cholesterol-lowering medications. Children may be screened if there is a strong family history.

Does exercise lower LDL cholesterol?

Regular aerobic exercise can modestly lower LDL cholesterol, typically by 5–10%. Exercise has a more pronounced effect on raising HDL cholesterol and lowering triglycerides. The most significant LDL improvements come from combining regular physical activity with dietary changes such as reducing saturated fat and increasing soluble fiber.

What does slightly high LDL cholesterol mean?

A slightly high LDL, generally in the 130–159 mg/dL range (borderline high), means cholesterol is above optimal but not severely elevated. Whether this level requires treatment depends on other cardiovascular risk factors. For many people, dietary improvements and increased physical activity may be sufficient to bring LDL back into a healthier range.

Sources

  • American Heart Association. Cholesterol Medications. heart.org.
  • Mayo Clinic. High Cholesterol — Diagnosis and Treatment. mayoclinic.org.
  • National Heart, Lung, and Blood Institute (NHLBI). Blood Cholesterol. nhlbi.nih.gov.
  • MedlinePlus. LDL: The “Bad” Cholesterol. U.S. National Library of Medicine.
  • Grundy SM, Stone NJ, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol. J Am Coll Cardiol. 2019;73(24):e285-e350.

Related Tests and Biomarkers

HDL Cholesterol Total Cholesterol Triglycerides CRP Lipid Panel

Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Reference ranges vary by laboratory and individual factors. Always discuss results with a qualified healthcare provider.