LDL Cholesterol (LDL-C)

•RCT evidence— Decades of statin and PCSK9 outcomes data

What it measures

LDL-C is the cholesterol mass carried in LDL particles, calculated from total cholesterol, HDL, and triglycerides via the Friedewald or Martin- Hopkins equation, or measured directly. It tracks closely with apoB particle number in most adults — but not always.

When LDL-C misleads

The number of atherogenic particles, not their cholesterol load, drives cardiovascular risk. Two scenarios where LDL-C underestimates risk:

• Hypertriglyceridaemia / metabolic syndrome: small dense LDL particles carry less cholesterol each, so LDL-C looks "fine" while apoB is high.
• Diabetes and chronic kidney disease: similar discordance.

If apoB is available, prefer it. If only LDL-C, treat it like the proxy it is.

Targets

ESC 2019 / AHA / ACC 2018 guidance, simplified:

Risk category	Target LDL-C
Low risk, primary	<115 mg/dL
Moderate primary	<100
High risk (diabetes, CKD, FH)	<70
Very high (established ASCVD)	<55
Very high + recurrent events	<40

Related entries

ApoB, Statins, Cardiovascular disease.