What does the Lipoprotein Subfractions (LDL size, small LDL particle number, HDL particle number, VLDL particle number and size) test measure?

Why is Lipoprotein Subfractions (LDL size, small LDL particle number, HDL particle number, VLDL particle number and size) measured?

Subfraction analysis is a genuine differentiator of NMR relative to simpler particle measures, and the small dense LDL phenotype is a recognised and reproducible metabolic pattern. Its independent clinical utility is more limited than often presented: small dense LDL correlates strongly with total LDL particle number and with triglyceride and insulin-resistant states, and the evidence that it adds risk prediction beyond LDL-P or apolipoprotein B once those are accounted for is inconsistent. Subfraction data are best regarded as descriptive of metabolic phenotype rather than as independently actionable, and treatment decisions should rest on particle number and global risk.

Reference ranges

Standard reference

Reported against population percentiles for each subfraction; thresholds are not standardised across methods and are not outcome-validated treatment targets

Functional medicine optimal

Not applicable — subfraction values describe metabolic phenotype and are not established as independent treatment targets

Units

nmol/L, µmol/L, nm

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