Did my ApoB really change?
Two results and their dates. The change gets a stamp: Can't tell yet, Probably real or Real change.
First test
Second test
Fasting doesn't matter for ApoB: the 2026 guideline says the test is unaffected by it, so this tool doesn't ask.
−8mg/dL, −7.7%
About 15% either way (16 mg/dL): a change inside this can be noise.
Past 23% (24 mg/dL): a real change.
One draw at each end. The bands come from how much ApoB moves in one person (6.4%) and how much a lab's test varies (5 to 6%).
Want a steadier answer? Two draws a few days apart at each end bring the bands down to about 11% and 17%.
ApoB's band is narrower than LDL's (about 23% against 29% for a real change), since ApoB is measured, not worked out.
What your stamp means
- Can't tell yet: the change is inside normal test-to-test noise, under about 15%. Keep going and test again, or use two draws at each end.
- Probably real: about 15% or more. One more test at the same lab confirms it.
- Real change: about 23% or more. Something moved, so look at what changed in the weeks before, a medicine above all.
A clean retest, once
- Same lab as last time, since labs differ by a few points.
- The right gap: 6 to 12 weeks after a food change holds, and 4 to 12 weeks after a medicine change, as the guideline checks.
- No fasting needed, but not while you're sick.
- For a steadier answer, two draws a few days apart at each end bring the lines down to about 11% and 17%.
How it works
ApoB moves about 6.4% from one week to the next in the same person with nothing changed, and a lab's test adds 5 to 6% of its own. Together they set how big a change has to be before it's likely real: about 15% at the 80% line and about 23% at the 95% line. At an ApoB of 100, that's 15 and 23 mg/dL. At 120, it's 18 and 28.
Fasting doesn't matter for ApoB, so the tool doesn't ask. The guideline checks 4 to 12 weeks after a change, so two tests closer than 4 weeks say little. Two draws a few days apart at each end, averaged, bring the bands down to about 11% and 17%.
5 sources
- Kafonek SD, Derby CA, Bachorik PS, the biological variation of ApoB in lipid clinic patients, Clinical Chemistry, 1992pubmed.ncbi.nlm.nih.gov
- Marcovina SM, Gaur VP, Albers JJ, the biological variation of lipids and apolipoproteins in 20 healthy adults, Clinical Chemistry, 1994pubmed.ncbi.nlm.nih.gov
- Soffer DE, Marston NA, Maki KC and others, Role of apolipoprotein B in the clinical management of cardiovascular risk in adults: an Expert Clinical Consensus from the National Lipid Association, Journal of Clinical Lipidology, 2024pmc.ncbi.nlm.nih.gov
- Blumenthal RS, Morris PB, Gaudino M and others, 2026 ACC/AHA guideline on the management of dyslipidemia, JACC, 2026doi.org
- Matthews KA and others, the SWAN study of 1,054 women through the menopause, JACC, 2009pubmed.ncbi.nlm.nih.gov
