LDL Small measures the count of small, dense LDL particles, a specific subfraction of LDL that's particularly atherogenic. Small LDL particles penetrate artery walls more easily, stay in circulation longer, and oxidize more readily than larger LDL particles.
Elevated small LDL is tightly associated with insulin resistance, metabolic dysfunction, and higher cardiovascular event rates even when total LDL-C is normal. Lifestyle changes targeting insulin resistance (carbohydrate reduction, exercise) typically shift particles toward larger, less atherogenic sizes.
Optimal LDL Small (ION): 0-300 nmol/L.
Typically re-tested every 12 weeks.