ApoB test: how to measure it, what it costs and how to prepare

• High triglycerides. The ESC/EAS recommends ApoB with non-HDL-C when triglycerides are raised [4]. Canada prefers ApoB or non-HDL-C over LDL-C whenever triglycerides exceed 133 mg/dL (1.5 mmol/L)1.5 mmol/L (133 mg/dL) [2]. The 2018 AHA/ACC guideline named triglycerides of 200 mg/dL or more as a relative indication [5].
• Diabetes, obesity, metabolic syndrome or very low LDL-C. These are the situations where the ESC/EAS says LDL-C may underestimate particle number [4].
• Residual risk on treatment. The 2026 ACC/AHA guideline uses ApoB selectively once LDL-C and non-HDL-C goals are met, particularly with triglycerides above 200 mg/dL, diabetes, or LDL-C below 70 mg/dL [6]. It does not recommend universal ApoB testing [6].
• Family screening. The NLA suggests ApoB to help clarify a possible genetic lipid disorder in relatives of people with high ApoB [3].

If you are already tracking LDL-C and want to understand the difference, see ApoB vs LDL. Whether to test is a conversation to have with your clinician.

The European Atherosclerosis Society and the European Federation of Clinical Chemistry found that fasting does not change ApoB, HDL-C, ApoA1 or Lp(a) [1]. Meal-derived chylomicrons carrying ApoB-48 are typically under 1 percent of ApoB particles even after eating [4], and more than 95 percent of ApoB is ApoB-100 in people without severe hypertriglyceridemia [3].

Triglycerides do rise after a meal, by about 27 mg/dL (0.3 mmol/L)0.3 mmol/L (27 mg/dL) on average [4], which is one reason calculated LDL-C is less reliable than ApoB in non-fasting samples. If your lab or clinician asks you to fast for other tests on the same draw, follow their instructions.

The EAS and EFLM recommend that labs flag ApoB of 100 mg/dL (1.0 g/L)1.0 g/L (100 mg/dL) or higher as abnormal [1]. That flag is not a treatment goal. Your clinician compares your number with the goal or threshold for your risk category, which may be lower; see normal ApoB levels.

Particle research sometimes reports ApoB in nmol/L. In UK Biobank, a mean ApoB of 1.03 g/L corresponded to about 1,870 nmol/L [7].

The National Lipid Association describes ApoB assays as low cost to perform and highly accurate [3]. It also reports that insurers in the US sometimes deny payment, require prior authorization or charge large co-payments, partly because the 2018 AHA/ACC guideline did not make ApoB a treatment target, and calls labeling the test experimental unsupported by the evidence [3]. The EAS/EFLM consensus noted that ApoB comes at extra cost compared with the standard panel [1].

We do not list prices here because they change often and differ widely by region and payer. Ask your clinic or lab for the cash price and whether your plan covers it when ordered for one of the guideline reasons above.

The NLA lists these moments to consider measuring ApoB [3]:

• At the first lipid evaluation, to look for discordance with LDL-C and non-HDL-C.
• 4 to 12 weeks after starting, escalating or reducing lipid-lowering therapy.
• After a clinical or metabolic change: significant weight change, new kidney, liver or thyroid disease, new or worsening high blood sugar, or new medications that affect lipids.
• When screening relatives for a genetic lipid disorder.

For lipid screening in general, the 2026 ACC/AHA guideline calls for repeat testing every 5 years after age 19 [8]. ApoB varies less than calculated LDL-C, with a typical lab coefficient of variation of 5 to 6 percent [3], so a change of a few mg/dL between tests may be noise. In the app, the longevity focus protocol flags labs older than 120 days so your trend stays current.

The 2025 ESC/EAS update recommends measuring Lp(a) at least once in every adult [9], and the Canadian [2] and 2026 US guidance [8] say the same. ApoB counts Lp(a) particles but cannot single them out, so a normal ApoB does not rule out high Lp(a). The full comparison is on ApoB vs Lp(a) and the Lp(a) hub.