Small dense LDL-5 (sdLDL-5) is one of the smallest and most pathogenic LDL particle subfractions. At this level of particle density and size, the atherogenic properties are at their most pronounced — these particles are extremely prone to oxidation, resist receptor-mediated clearance, and penetrate and are retained in the arterial wall with greatest efficiency.
The small dense LDL pattern (sdLDL-5 through 7) is the lipoprotein signature of severe insulin resistance and advanced metabolic dysfunction. Its presence alongside high triglycerides and low HDL forms the classic atherogenic dyslipidaemia triad — a pattern that carries cardiovascular risk disproportionate to what standard lipid panels suggest.
FAQs
What is atherogenic dyslipidaemia?
Atherogenic dyslipidaemia refers to the lipid triad of elevated triglycerides, low HDL, and small dense LDL (including sdLDL-5). This pattern is the lipid signature of insulin resistance and carries very high cardiovascular risk disproportionate to the apparent LDL level.
Who should have sdLDL-5 tested?
People with metabolic syndrome, type 2 diabetes, unexplained cardiovascular disease, or very high triglycerides despite apparently normal LDL benefit most from sdLDL subfraction analysis.
How does this relate to the triglyceride/HDL ratio?
A high triglyceride/HDL ratio (above 2.0 mmol/mmol) is a useful surrogate marker for the small dense LDL pattern. It predicts Pattern B lipid phenotype without formal subfraction testing.
Can sdLDL-5 be lowered?
Yes. Aggressive carbohydrate restriction, insulin sensitisation, weight loss, fibrates, and high-dose omega-3 fatty acids all reduce sdLDL-5 levels.
