Apolipoprotein B (ApoB) Unit Converter
Apolipoprotein B (ApoB) Unit Converter
Convert apolipoprotein B between g/L, mg/dL and mg/L — and read the answer against the right number, because the apoB target and the apoB reference interval are nowhere near each other.
Apolipoprotein B (ApoB) converter
g/L ⇄ mg/dLApolipoprotein B 1.05 g/L, read against the general population figure
Formula and conversion factors
g/L = mg/dL ÷ 100
mg/L = g/L × 1000
- × 100
- g/L is the SI convention and mg/dL the US one; a gram is 1,000 mg and a litre is 10 dL, so the factor is exactly 100 and nothing about the assay enters into it
- no molar unit
- apoB-100 is a single 512 kDa protein, but laboratories report it by mass and no molar unit is in clinical use, so none is offered here
- one per particle
- every atherogenic lipoprotein carries exactly one apoB molecule, which is what makes the mass concentration proportional to the particle count
- target ≠ reference interval
- the population reference interval reaches 1.5 g/L in men, well above every treatment target. An apoB inside the laboratory's range is not an apoB at goal
Worked example
Apolipoprotein B 1.05 g/L, read against the general population figure
1.05 × 100 = 105 mg/dL
1.05 × 1,000 = 1,050 mg/L
Above the desirable general-population figure of 0.90 g/L (90 mg/dL)
Also above the ESC/EAS secondary goals of 0.80 g/L at high risk and 0.65 g/L at very high risk
And yet comfortably inside the population reference interval of 0.6–1.5 g/L for men — which is why the interval is the wrong thing to read it against
Targets and reference intervals are different numbers
| g/L | mg/dL | |
|---|---|---|
| ESC/EAS 2019 secondary goal — very high cardiovascular risk | < 0.65 | < 65 |
| ESC/EAS 2019 secondary goal — high cardiovascular risk | < 0.80 | < 80 |
| ESC/EAS 2019 secondary goal — moderate cardiovascular risk | < 1.00 | < 100 |
| Desirable in an otherwise healthy adult | < 0.90 | < 90 |
| Population reference interval, men (FINRISK 2007) | 0.6 – 1.5 | 60 – 150 |
| Population reference interval, women (FINRISK 2007) | 0.6 – 1.3 | 60 – 130 |
When apoB and LDL cholesterol disagree
| Situation | What happens to the particles | Why apoB reads higher than LDL-C suggests |
|---|---|---|
| Raised triglycerides | Cholesteryl ester transfer depletes LDL of cholesterol | More particles are needed to carry the same cholesterol, so particle number outruns LDL-C |
| Metabolic syndrome, type 2 diabetes | Small dense LDL predominates | Each particle carries less cholesterol; LDL-C looks unremarkable while particle number is high |
| Already taking a statin | LDL-C falls further than particle number does | Residual risk tracks the particles that remain, which apoB counts and LDL-C under-reports |
| Raised Lp(a) | Lp(a) particles each carry one apoB | They are counted in apoB and largely invisible in a routine LDL-C |
A particle count, and the interval that hides it
The conversion is the least interesting thing on this page. Apolipoprotein B is reported in g/L in most of the world and in mg/dL in the United States, and the two differ by a factor of exactly 100: an apoB of 1.05 g/L is 105 mg/dL. No assay characteristic and no patient variable enters into that. What is worth getting right is what the number counts and which figure it is being read against.
ApoB counts particles. Every atherogenic lipoprotein — LDL, IDL, VLDL, chylomicron remnant and lipoprotein(a) — carries exactly one apoB-100 molecule, and it stays with the particle throughout its life in the circulation. The apoB concentration is therefore proportional to the number of atherogenic particles present, which is the quantity that determines how many can enter and be retained in the arterial wall. LDL cholesterol measures something different: the cholesterol those particles are carrying, which varies from particle to particle. When the cholesterol per particle falls, LDL-C falls with it while the particle count does not.
That divergence is not rare and it is not random. It concentrates in raised triglycerides, in metabolic syndrome and type 2 diabetes, in people with a low measured LDL-C, and in people already established on a statin — the groups whose residual risk is hardest to judge from a standard profile. Where apoB and LDL cholesterol disagree, outcomes follow apoB, and the 2019 ESC/EAS guidance accordingly allows apoB as an alternative primary measurement and prefers it over non-HDL cholesterol in people with high triglycerides, diabetes, obesity or very low LDL-C.
The last point is the one a laboratory report will not make for you. The population reference interval for apoB runs to about 1.5 g/L in men and 1.3 g/L in women, while the ESC/EAS secondary goals are 1.00, 0.80 and 0.65 g/L as cardiovascular risk rises. Every target lies below the top of the reference interval, so a result can be flagged as normal by the laboratory and still be well above goal. Decide the risk category first, on the clinical assessment, and read the apoB against the target that category carries — not against the interval printed beside it.
Frequently asked questions
How do I convert apoB from g/L to mg/dL?
Multiply by 100. An apoB of 1.05 g/L is 105 mg/dL, and 0.80 g/L is 80 mg/dL. To go the other way, divide the mg/dL figure by 100. There is no molar unit for apoB, because laboratories report it as a mass concentration.
What is a normal apolipoprotein B level?
The population reference interval is roughly 0.6–1.5 g/L in men and 0.6–1.3 g/L in women, but that describes what people have rather than what is desirable. Below about 0.90 g/L (90 mg/dL) is the usual figure quoted as desirable in an otherwise healthy adult.
What is the apoB target on treatment?
The 2019 ESC/EAS secondary goals are below 1.00 g/L (100 mg/dL) at moderate cardiovascular risk, below 0.80 g/L (80 mg/dL) at high risk and below 0.65 g/L (65 mg/dL) at very high risk. The risk category is decided clinically before the apoB is read against it.
Why is apoB better than LDL cholesterol?
Because each atherogenic particle carries exactly one apoB molecule, so apoB counts particles while LDL-C measures the cholesterol inside them. The two diverge when cholesterol per particle changes — with high triglycerides, metabolic syndrome, diabetes, or on a statin — and risk follows the particle count.
Does apoB need a fasting sample?
No. Apolipoprotein B is a direct immunoassay measurement of a protein and is not appreciably affected by fasting status, which is one of the practical advantages it has over a calculated LDL cholesterol.
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References
- Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Eur Heart J. 2020;41(1):111–188.
- Sniderman AD, Thanassoulis G, Glavinovic T, et al. Apolipoprotein B particles and cardiovascular disease: a narrative review. JAMA Cardiol. 2019;4(12):1287–1295.
- Leiviskä J, Sundvall J, Alfthan G, Jauhiainen M, Salomaa V. Apolipoprotein A-I, apolipoprotein B, and apolipoprotein B/apolipoprotein A-I ratio: reference intervals compared with values in different pathophysiological conditions from the FINRISK 2007 study. Clin Chim Acta. 2011;412(11–12):1146–1150.