What is the normal level of Low-Density Lipoprotein (LDL) in millimoles per liter (mmol/L)?

From the Guidelines

The normal level of LDL cholesterol is generally considered to be less than 2.6 mmol/L for most adults, as recommended by the most recent guidelines. This target may vary depending on a person's overall cardiovascular risk profile, including factors such as age, family history, smoking status, diabetes, and hypertension. According to the 2019 American Heart Association/American College of Cardiology/Multisociety Cholesterol Guideline 1, for individuals at high risk of cardiovascular disease, the target is often even lower at less than 1.8 mmol/L. LDL cholesterol is often called "bad cholesterol" because elevated levels can lead to plaque buildup in arteries, increasing the risk of heart disease and stroke.

Some key points to consider when evaluating LDL levels include:

• The 2018 Cholesterol Clinical Practice Guidelines recommend reduction of low-density lipoprotein cholesterol (LDL-C) levels with high-intensity or maximally tolerated statin therapy for patients with clinical ASCVD 1.
• The guideline recommends an LDL-C threshold of 1.8 mmol/L (70 mg/dL) as reasonable for adding a nonstatin medication (ezetimibe or proprotein convertase subtilisin/kexin type 9 [PCSK9] inhibitors) to maximally tolerated statin therapy for patients at very high risk for ASCVD 1.
• Regular cholesterol screening is recommended for adults, typically starting at age 20 and repeating every 4-6 years for those at average risk.
• If LDL levels are elevated, lifestyle modifications like a heart-healthy diet low in saturated fats, regular exercise, weight management, and avoiding smoking can help lower them.
• In some cases, medication such as statins may be prescribed if lifestyle changes alone are insufficient to reach target levels.

It's worth noting that the European Society of Cardiology (ESC) and the European Atherosclerosis Society (EAS) also provide guidelines for the management of dyslipidemias, which include recommendations for LDL-C targets 1. However, the most recent and highest quality study, the 2019 American Heart Association/American College of Cardiology/Multisociety Cholesterol Guideline 1, provides the most up-to-date and evidence-based recommendations for LDL-C targets.

From the Research

Normal Level of LDL

The normal level of low-density lipoprotein (LDL) cholesterol is a topic of interest in the medical field.

• According to a study published in the Journal of the American College of Cardiology 2, the normal LDL cholesterol range is 50 to 70 mg/dl, which is equivalent to approximately 1.29 to 1.81 mmol/L.
• This range is based on the LDL levels of native hunter-gatherers, healthy human neonates, free-living primates, and other wild mammals that do not develop atherosclerosis.
• Another study published in Atherosclerosis 3 reported that atorvastatin treatment resulted in a 45% reduction of LDL cholesterol, with a mean LDL level of 2.27 +/- 0.89 mmol/L after treatment.
• However, it's worth noting that the optimal LDL level may vary depending on individual factors, such as risk of cardiovascular disease and other health conditions.

LDL Levels and Cardiovascular Risk

• A study published in Current Medical Research and Opinion 4 found that statin treatment can reduce the relative risk of cardiovascular disease by 24-37%, regardless of age, sex, or prior history of coronary heart disease.
• The same study noted that more intensive lipid-lowering regimens could provide additional clinical benefits, and that targeting inflammatory mediators of atherosclerosis and combination therapy to raise high-density lipoprotein cholesterol (HDL-C) and lower LDL-C may be promising new strategies for primary and secondary prevention of atherosclerotic disease.
• A study published in the Journal of the American College of Cardiology 2 suggested that lowering LDL to <70 mg/dl (approximately 1.81 mmol/L) can minimize atherosclerosis progression and coronary heart disease events.

Measurement of LDL Cholesterol

• A study published in The American Journal of Cardiology 5 discussed the limitations of estimating LDL cholesterol levels using the Friedewald formula, which can become less accurate as plasma triglyceride concentrations increase.
• The study suggested that measuring non-HDL cholesterol (serum cholesterol minus HDL cholesterol) may be a simpler and more accurate method for identifying dyslipoproteinemias, assessing risk, and evaluating the results of hypolipidemic therapy.