What is LDL/ApoB ratio?
LDL cholesterol measures how much cholesterol sits in your LDL particles, not how many particles there are. ApoB does the reverse: every LDL particle carries exactly one molecule of ApoB, and so do the VLDL and IDL particles LDL arises from, so your ApoB is a count of every particle that can carry cholesterol into the vessel wall. Divide the cholesterol by the number of particles and you are left with how much cholesterol each particle holds on average, and that is a measure of how large the particles are. That is the idea behind the ratio. Large, buoyant LDL particles are full of cholesterol and give a high result; small, dense particles carry little cholesterol each and give a low one. A result of 1.2, calculated on mg/dl, corresponds to a mean particle diameter of 25.5 nm, the boundary between the pattern with large particles and the pattern with small, dense ones (Tani et al., 2017). Below that boundary you have many particles for little cholesterol, and that is exactly the combination in which a tidy LDL number says less than it seems. Your report does not print the ratio, and Dutch labs report LDL in mmol/l and ApoB in g/l while the boundary is published on mg/dl. That is why the calculator on this page converts first: LDL times 38.67 and ApoB times 100. Divide the Dutch units straight and you get a number around 3 that has nothing to do with the boundary.
Why is LDL/ApoB ratio relevant?
Small, dense LDL particles are the particles that most easily pass through the vessel wall, linger there longer and oxidise faster, and therefore weigh more than the same cholesterol in large particles. In the Quebec Cardiovascular Study the number of heart events in people with particles of 25.5 nm or smaller rose as LDL rose, while in people with particles of 26.0 nm or larger it did not (Tani et al., 2017). The size of the particles therefore helps decide what an LDL number means. The second reason is the case in which LDL and ApoB contradict each other. An LDL inside the band with an ApoB above it means many small particles, and then the ApoB weighs more than the LDL. The ratio turns that contradiction into one number you can follow over the years. It falls with high triglycerides, belly fat and insulin resistance, because the liver then makes the small, dense variant, and in a Japanese cohort the ratio was lower in people with type 2 diabetes and in people with narrowed coronary arteries (Tani et al., 2017). In a German cohort the inverse ratio, ApoB per LDL cholesterol, went with more cardiovascular deaths and with the amount of small, dense LDL particles (Silbernagel et al., 2022). The honest limitation is that the ratio is an estimate and not a measurement of the particles themselves. The LDL in the numerator is, at most labs, a calculation from total cholesterol, HDL and triglycerides that comes out too low with high triglycerides and after a meal, and then the ratio falls along without your particles changing. That is why you always read it fasting, beside the ApoB and the LDL themselves, and beside the triglycerides.
LDL/ApoB ratio decision limits
What counts beside the number:
- Whether you were drawn fasting, because the calculated LDL in the numerator comes out too low after a meal
- The ApoB and the LDL themselves, because the same ratio fits a high and a low particle count
- Your triglycerides, because they drive the small, dense variant and usually explain a low ratio
- Non-HDL and LDL, the measures the risk estimate works on and the ratio says nothing about
- How much belly fat you carry, how much you exercise and how much sugar and alcohol you drink, because those steer particle size
- Your earlier results from the same lab, because without a lab band your own course is the reference point
No lab prints the LDL/ApoB ratio and there is no national reference value; what exists is a cut-off from research. Below 1.2, calculated on mg/dl, small, dense LDL particles dominate; above it the particles are large and buoyant, and there is no upper limit that points to a condition. The ratio says something about the shape of your particles, not about the amount: for the risk estimate Dutch doctors work with LDL, non-HDL and ApoB. Calculate the ratio fasting from the same draw, with the conversion to mg/dl.
LDL/ApoB ratio = (LDL cholesterol × 38.67) ÷ (ApoB × 100), with LDL in mmol/l and ApoB in g/l
Tani et al., 2017The two constants are conversions, not assumptions: 38.67 turns cholesterol in mmol/l into mg/dl, and 100 turns ApoB in g/l into mg/dl. The boundary of 1.2 is published on those American units, so without the conversion the result would sit around 3 and have nothing to be set against. Both values come from the same lipid profile.
( × 38,67) ÷ ( × 100) =
LDL/ApoB ratio high or low: what it means
A low ratio, below 1.2, means your LDL particles are on average small and dense: many particles for little cholesterol. The most common reason is that you were not drawn fasting, because the calculated LDL then comes out too low. Structurally it is the pattern of high triglycerides, belly fat and insulin resistance, in which the liver makes the small, dense variant, often years before the fasting glucose moves. A low LDL with a normal ApoB gives the same result, and then the ApoB is the value that counts. A high ratio means large, buoyant particles, and that is the favourable side: there is no upper limit that points to a condition. What does hold is that a high LDL with a high ratio is still a high LDL; the ratio says something about the shape of the particles, not about the amount. For the risk estimate Dutch doctors work with LDL, non-HDL and ApoB, and the ratio sits beside those, not in their place. What you do about a low ratio is what you do about high triglycerides: less sugar, soft drinks and alcohol, because the liver turns those into triglycerides and small particles, more fibre and unsaturated fat, vigorous exercise and losing weight if you carry belly fat. The ratio then moves on two sides: the triglycerides fall and the particles grow. Count on six to twelve weeks and then have blood drawn fasting, at the same lab as last time. The ratio belongs beside the ApoB, which counts the particles, beside the LDL itself, beside the triglycerides, which drive the small, dense variant, and beside non-HDL, the measure the risk estimate works on.
What lowers it
Many particles for little cholesterol, and the question is whether that is your particles or the draw.
| Cause | How often |
|---|---|
| Ate or drank recentlyThe calculated LDL comes out too low after a meal, and the ratio falls along without the particles changing | Often |
| Belly fat and insulin resistanceThe liver makes more triglycerides and more small, dense LDL particles, often years before the fasting glucose moves | Often |
| Type 2 diabetes mellitusThe same pattern, further along; in a Japanese cohort the ratio was lower in people with diabetes | Often |
| A low LDL with a normal ApoBLittle cholesterol per particle while the particle count is ordinary; the ApoB is then the value to read | Sometimes |
How does a LDL/ApoB ratio blood test work?
- Referral
- Not needed. The ratio follows from two values in the same lipid profile, LDL and ApoB, and you calculate it with the calculator on this page; in the Netherlands nobody prints it.
- Fasting
- Yes, because the LDL in the numerator is calculated from the triglycerides at most labs, and those rise for hours after a meal. Eight to twelve hours without food, only water, and no alcohol the evening before.
- When
- In the morning, fasting, on an ordinary day. Six to twelve weeks after a change in diet, weight or alcohol to see the effect on the particles.
- The draw
- One tube of blood from a vein in your arm. LDL and ApoB come from the same tube, and the triglycerides and the fasting glucose can be added straight away.
- Which test
- LDL/ApoB ratio is in the comprehensive test (€229) and in .
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is the LDL/ApoB ratio?
Your LDL cholesterol divided by your ApoB, both from the same lipid profile and converted to mg/dl. ApoB counts the particles, because each particle carries exactly one, and LDL weighs the cholesterol inside them. The ratio is therefore cholesterol per particle, and that says how large your LDL particles are on average. It is a calculation from research, not a test a Dutch lab prints.
What is a healthy LDL/ApoB ratio?
Above 1.2, calculated on mg/dl. That boundary corresponds to a mean particle diameter of 25.5 nm, where the pattern with large, buoyant particles passes into the pattern with small, dense ones. The higher, the larger the particles, and there is no upper limit that points to a condition. A high LDL still remains a high LDL: the ratio says something about the shape, not about the amount.
What does a low LDL/ApoB ratio mean?
That you have many particles for little cholesterol: small, dense LDL. The most common reason is that you were not drawn fasting, because the calculated LDL comes out too low after a meal. Structurally it is the pattern of high triglycerides, belly fat and insulin resistance, in which the liver makes the small, dense variant. A low LDL with a normal ApoB gives the same result, and then the ApoB counts.
Why do I have to convert to mg/dl?
Because the boundary of 1.2 is published on American units. Dutch labs report LDL in mmol/l and ApoB in g/l; divide those straight and you get a number around 3 that you cannot set against anything. The calculator therefore converts first: LDL times 38.67 and ApoB times 100. Example: LDL 3.0 mmol/l is 116 mg/dl, ApoB 0.9 g/l is 90 mg/dl, and the ratio is 1.29.
My LDL is fine but my ApoB is high. What does the ratio say then?
That your LDL particles are small and dense: many particles for little cholesterol, and the ratio then comes out below 1.2. In that case the ApoB weighs more than the LDL, because the number of particles decides how much can enter the vessel wall. Look beside the ratio at your triglycerides and your waist, because that is usually where this pattern comes from, and follow the ApoB over the years.
Do I need to fast?
Yes. The LDL in the numerator is calculated at most labs from total cholesterol, HDL and triglycerides, and the triglycerides rise for hours after a meal. The LDL then comes out too low and the ratio falls along, without anything changing in your particles. Eight to twelve hours without food, only water, and no alcohol the evening before; the ApoB itself hardly responds to food.
What do I do with a ratio below 1.2?
What you do about high triglycerides, because they drive the small, dense particles: cut soft drinks, fruit juice and sweets, drink less alcohol, eat fibre, oily fish and unsaturated fat, exercise vigorously and lose weight if you carry belly fat. The particles then grow and the ratio rises. Count on six to twelve weeks and then have blood drawn fasting, at the same lab. Also look at your fasting glucose and HbA1c.
Why is this ratio on the site if nobody prints it?
Because you meet it in reports and calculators from outside the Netherlands and then want to know where the number comes from, and because it captures the contradiction between a good LDL and a high ApoB in one number. The page explains the calculation and points to the values that do appear on your report. For the risk estimate Dutch doctors work with LDL, non-HDL and ApoB, not with this ratio.
Which tests include LDL/ApoB ratio?
LDL/ApoB ratio is in the comprehensive test (€229) and in .
Related biomarkers
Read on
Sources
- 1.Tani S, Yagi T, Atsumi W et al., Relation between low-density lipoprotein cholesterol/apolipoprotein B ratio and triglyceride-rich lipoproteins in patients with coronary artery disease and type 2 diabetes mellitus, Cardiovascular Diabetology. 2017. pubmed.ncbi.nlm.nih.gov
- 2.Hirano T, Ito Y, Yoshino G, Measurement of small dense low-density lipoprotein particles, Journal of Atherosclerosis and Thrombosis. 2005. pubmed.ncbi.nlm.nih.gov
- 3.Silbernagel G, Scharnagl H, Saely CH et al., The LDL Apolipoprotein B-to-LDL Cholesterol Ratio: Association with Cardiovascular Mortality and a Biomarker of Small, Dense LDLs, Biomedicines. 2022. pubmed.ncbi.nlm.nih.gov
- 4.CVRM, Dutch multidisciplinary guideline on cardiovascular risk management, module on estimating cardiovascular risk. 2024. richtlijnendatabase.nl
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
Read about our scientific approachShare