LDL Cholesterol
Cholesterol carried by low-density lipoprotein particles, the main driver of artery plaque.
| Typical reference range | below 99 mg/dL |
| Commonly cited optimal range | below 70 mg/dL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Low-density lipoproteins deliver cholesterol from the liver to tissues. LDL-C measures the cholesterol content of these particles, and is usually calculated (Friedewald, Martin-Hopkins or NIH/Sampson equation) from total cholesterol, HDL and triglycerides rather than measured directly.
Why it matters
LDL particles can enter the artery wall and become trapped, starting and growing atherosclerotic plaque. Decades of genetic and trial evidence show that lower LDL-C over time means lower risk of heart attack and stroke, which is why it is the primary target of most lipid guidelines.
What a high result can mean
High LDL-C is commonly due to inherited factors (familial hypercholesterolemia often gives LDL-C above 190 mg/dL), saturated and trans fat intake, excess weight, hypothyroidism, nephrotic syndrome, cholestasis and certain drugs (anabolic steroids, some immunosuppressants). Some people on ketogenic or very low-carbohydrate diets also see marked rises.
What a low result can mean
Low LDL-C is generally associated with lower cardiovascular risk and is a treatment goal for many people. Unexpectedly low values without medication may reflect hyperthyroidism, malabsorption, liver disease or rare genetic conditions (hypobetalipoproteinemia).
What affects the result
Calculated LDL becomes less accurate when triglycerides are high (above ~400 mg/dL) or LDL is very low; a direct LDL or ApoB is then preferred. Fasting usually changes LDL-C little. Dietary fat quality, soluble fiber, weight loss, thyroid function and medications (statins, ezetimibe, PCSK9 inhibitors) are major levers. ApoB and LDL particle number can reveal risk that LDL-C misses.
Units and conversion
Usually reported in mg/dL.
- From mmol/L: multiply by 38.67 to get mg/dL
Also called on lab reports
LDL, LDL-C, LDL-Cholesterol, LDL Chol Calc (NIH), LDL Cholesterol Calc, Low Density Lipoprotein, LDL Calc, LDL-C (Calculated), LDL Cholesterol, Direct, Direct LDL, LDL Chol
Related tests: Lipids & Cardiovascular Risk
This page is educational and does not replace advice from a healthcare professional.