Specialist marker · Heart and lipids
A small dense LDL (sdLDL) test measures the cholesterol in the smallest LDL particles, which slip into artery walls most easily and are the most plaque-prone. Two people with the same LDL can carry very different amounts. sdLDL is measured directly in TrueVitals Signature (£799); Ultimate estimates the same risk through ApoB and triglyceride ratios.
LDL cholesterol is carried in particles of different sizes. Large, buoyant LDL particles are cleared relatively easily. Small, dense particles stay in the blood longer, squeeze into artery walls more easily and are more easily damaged by oxidation, which drives plaque formation.
A standard LDL result tells you how much cholesterol is carried, not how it is packaged. A high share of small dense LDL can sit behind an LDL figure that looks perfectly normal.
Ultimate does not measure small dense LDL directly, but it gives strong proxies: ApoB (the total number of harmful particles), plus the triglyceride/HDL ratio and the atherogenic index of plasma, which both track closely with small dense LDL. Signature adds the direct measurement and the small LDL percentage.
| Option | Includes it | Price | What else you get |
|---|---|---|---|
| TrueVitals Signature | Yes | £799 incl. draw | Direct sdLDL and small LDL %, with ApoB, ApoE, Lp(a), homocysteine and the rest of Signature's 45 specialist markers. |
| TrueVitals Ultimate | No | £399 | Not measured directly. Ultimate has ApoB, triglyceride/HDL ratio and atherogenic index as proxies. |
| NHS GP | No | Not offered | Not part of NHS lipid testing. |
TrueVitals prices checked 5 November 2026. Every TrueVitals report is clinician-reviewed. Pay in instalments with Klarna or Clearpay. Signature is drawn at one of 70 Randox Health clinics; Ultimate at one of 103 partner clinics or with a home visit.
Keep it in proportion: small dense LDL adds detail, but ApoB and Lp(a) remain the strongest lipid markers of risk. Decisions about cholesterol treatment should be made with your GP using UK risk tools.
A private panel is a good way to get a baseline, understand a result in context and track it over time. It does not replace your GP for symptoms, and anything that needs follow-up is flagged in plain words in your report.
Small dense LDL on its own rarely tells the whole story. In TrueVitals panels it is reported with these related markers:
Particle for particle, yes. Small dense LDL enters artery walls more easily and stays in the blood longer, so it is considered the most plaque-prone form.
Not directly. Ultimate gives ApoB and triglyceride ratios that track it closely. Signature measures it directly.
Mostly by lowering triglycerides and improving insulin sensitivity: less sugar and refined carbohydrate, less alcohol, more exercise and weight loss if needed.
Yes. An overnight fast with water only gives the most reliable lipid results.
How this page was written: by James Smillie, founder of TrueVitals, reviewed by the TrueVitals clinical review team, using NHS and laboratory reference sources. Ranges are typical values; your report uses your lab's own ranges. TrueVitals sells the panels named on this page, so we have stated plainly what this test cannot do. Last updated 5 November 2026.
Signature: 230 biomarkers including all 45 specialist markers: small dense LDL, ApoE, homocysteine and more. £799 including the draw.
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