What does the LDL Particle Number test measure?

Why is LDL Particle Number measured?

LDL particle number is the principal output of this assay and the measure with the strongest supporting evidence. Atherogenesis is driven by the number of apoB-containing particles entering and being retained in the arterial wall rather than by their cholesterol content, so LDL-P is mechanistically the more relevant exposure. Where LDL-P and LDL-C are discordant — common in insulin resistance, metabolic syndrome, type 2 diabetes, and hypertriglyceridaemia — LDL-P tracks cardiovascular risk more closely, and this discordance is the principal reason to order the test. Apolipoprotein B conveys substantially the same information, is standardised and more widely available, and appears in guidelines where LDL-P largely does not.

Reference ranges

Standard reference

Population percentiles: <1000 nmol/L is often cited as desirable, approximately 1000–1299 as intermediate, and >1600 nmol/L as high risk

Functional medicine optimal

Values below approximately 1000 nmol/L are commonly cited as favourable, with lower targets applied in established atherosclerotic disease, though these are percentile cut-points rather than validated treatment targets

Units

nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.