In one sentence
Four ways of reading a lipid profile that each add something LDL cholesterol alone misses: all the cholesterol riding in the particles that can lodge in artery walls (non-HDL), two ratios that fold HDL in, and the cholesterol carried by the triglyceride-rich remnant particles.
Why it matters
Non-HDL cholesterol is total cholesterol minus HDL cholesterol, which leaves the cholesterol in every apolipoprotein B particle, LDL and the triglyceride-rich ones together; in 302,430 people from 68 studies it carried a hazard of 1.50 for coronary heart disease per standard deviation, and the authors concluded that lipid assessment could be simplified to total and HDL cholesterol, without fasting and without regard to triglycerides (Emerging Risk Factors Collaboration 2009); it is the measure that stands in for ApoB when ApoB has not been measured. The total-to-HDL ratio is the form New Zealand's cardiovascular assessment tools take, and the same collaboration found the non-HDL-to-HDL ratio as informative as the apolipoprotein ratio. The triglyceride-to-HDL ratio reads something else: insulin resistance. In 258 overweight adults without diabetes it identified the insulin-resistant third at a cut-point the paper gives as 3.0 in US units (printed as 1.8 in SI units; the arithmetic conversion gives about 1.3 in mmol/L, the figure the clinician specification uses), with 64 percent sensitivity and 68 percent specificity (McLaughlin 2003). Remnant cholesterol, the cholesterol in the triglyceride-rich particles, was tested for cause in 73,513 Copenhagen residents: a genetic increase of 1 mmol/L carried a causal odds ratio of 2.8 for ischemic heart disease, against an observational hazard of 1.4, and the effect was independent of HDL cholesterol (Varbo 2013). The European consensus flags non-fasting remnant cholesterol from 0.9 mmol/L and non-HDL cholesterol from 3.9 (Nordestgaard 2016).
What moves it
Everything that moves the lipid profile, with triglycerides doing most of the moving in the ratio and in remnant cholesterol: the last meal, alcohol, sugar and refined carbohydrate, weight, insulin resistance, and a short night. Non-HDL cholesterol follows LDL cholesterol and is the steadier of the four.
How to measure it well
They are arithmetic on one lipid profile, so the profile's rules apply: a fasting morning draw on the panel's day, no alcohol for 48 hours, the same laboratory. One caution matters: when the laboratory calculates LDL cholesterol by the Friedewald equation, remnant cholesterol computed from it is exactly triglycerides divided by 2.2, a restatement of the triglyceride result and not a new measurement; a directly measured LDL gives a remnant figure of its own.
How Vitality Tracker uses it
Computed only from one draw (the same-draw rule) and shown in the lipids panel beneath the profile, with the laboratory's own figures first where it prints them. VT's working optimal (v0.1), beneath in smaller type and marked working: non-HDL cholesterol below 2.6 mmol/L; remnant cholesterol below 0.5; triglyceride-to-HDL ratio below 0.87, with the insulin-resistance pattern of the Stanford study named from 1.3 as that study's; the total-to-HDL ratio carries the laboratory's range alone. When ApoB is present, VT reads it ahead of non-HDL cholesterol, and the discordance between ApoB and LDL cholesterol has its own entry. The atherogenic index of plasma, the log of the triglyceride-to-HDL ratio, may be shown as context with its author's bands. None of the four enters the Vitality Score.
How far to trust the number
Calculated: non-HDL cholesterol inherits little error, because total and HDL cholesterol are measured directly; the two triglyceride-based figures inherit the triglyceride result's day-to-day swing, and remnant cholesterol from a calculated LDL inherits the point above.
Sources
- Emerging Risk Factors Collaboration. JAMA 2009;302:1993–2000. doi:10.1001/jama.2009.1619
- McLaughlin T, et al. Ann Intern Med 2003;139:802–9. doi:10.7326/0003-4819-139-10-200311180-00007
- Varbo A, et al. Remnant cholesterol as a causal risk factor for ischemic heart disease. J Am Coll Cardiol 2013;61:427–36. doi:10.1016/j.jacc.2012.08.1026
- Nordestgaard BG, et al. Eur Heart J 2016. doi:10.1093/eurheartj/ehw152
- Vitality Tracker, Clinician report content specification (derived indices); optimal set v0.1 (working).