Clinical Biochemistry & Preventive Cardiology & Family Medicine
Non-HDL-C (non-HDL cholesterol)
Non-HDL cholesterol (non-HDL-C) is a calculated lipid parameter representing the sum of cholesterol contained in all atherogenic plasma lipoproteins - i.e. all lipoproteins except HDL - including LDL (low-density lipoprotein), VLDL (very low-density lipoprotein), IDL (intermediate-density lipoprotein), Lp(a) (lipoprotein(a)) and chylomicron residues. Its calculation formula is absolutely straightforward: non-HDL-C = total cholesterol - HDL-C. This parameter has a major practical and clinical advantage over LDL-C calculated by the Friedewald formula - it requires no fasting on the part of the patient, can be calculated from a standard lipid panel performed at any time of day, and is not subject to the estimation errors introduced by the Friedewald formula in the presence of hypertriglyceridemia (which underestimates LDL-C when triglycerides exceed 4.5 mmol/L). More fundamentally, non-HDL-C captures the entire atherogenic risk associated with lipoproteins, as all non-HDL lipoproteins contain apolipoprotein B (apoB) on their surface - apoB being the structural protein enabling their penetration into the arterial wall and their role in atherosclerotic plaque formation. Canadian lipidology recommendations (Canadian Cardiovascular Society Guidelines 2021) and European ESC/EAS 2019 guidelines recognize non-HDL-C as a cardiovascular risk marker at least as powerful as LDL-C, and superior to the latter in certain high-risk populations - particularly patients with type 2 diabetes, metabolic syndrome, hypertriglyceridemia, nephrotic syndrome or secondary prevention - for whom non-LDL lipoproteins (VLDL + IDL + Lp(a)) account for a significant proportion of residual risk not captured by LDL-C alone.
Biology and lipoproteins included in non-HDL-C
- LDL (low-density lipoprotein): main component of non-HDL-C (represents 70 to 80 % of non-HDL-C in a fasting individual) + most studied lipoprotein in cardioprotection + each LDL contains one molecule of apoB-100 + transport of cholesterol from the liver to peripheral tissues + oxidized LDL (oxLDL) are particularly atherogenic (taken up by macrophages → foam cells → fatty streak → atheromatous plaque)
- VLDL (very-low-density lipoprotein): synthesized by the liver + transport triglycerides to peripheral tissues + each VLDL contains one apoB-100 molecule + remnant VLDL and IDLs (products of VLDL catabolism) are directly atherogenic + explanation of why non-HDL-C is a better marker than LDL-C in hypertriglyceridemic patients (as VLDL levels are then very high)
- IDL (intermediate-density lipoproteins) products of VLDL catabolism by lipoprotein lipase + highly atherogenic (small dense particles that easily penetrate the arterial wall) + included in non-HDL-C but absent from Friedewald calculated LDL-C
- Lp(a) — lipoprotein(a) variant génétique du LDL contenant une apolipoprotéine(a) liée à l'apoB-100 par un pont disulfure + facteur de risque cardiovasculaire indépendant + concentrations déterminées à 80–90 % génétiquement + incluse dans le non-HDL-C + non reflétée par le LDL-C standard + à doser séparément si suspicion de risque résiduel élevé malgré LDL-C contrôlé
- Chylomicron remnants: Dietary lipid digestion products + directly atherogenic + elevated in the postprandial state + explanation of non-HDL-C's ability to capture postprandial risk even on a non-fasting sample
Normal Values and Therapeutic Targets
| Population and risk level | Recommended non-HDL-C target | Target LDL-C |
|---|---|---|
| General adult population (low risk) | < 3.5 mmol/L (desirable) + < 4.0 mmol/L (acceptable) | < 3.0 mmol/L (desirable) |
| Intermediate cardiovascular risk | < 3.2 mmol/L according to Canadian SCC 2021 guidelines | < 2.0 mmol/L or reduction ≥ 50 % of LDL-C |
| High cardiovascular risk (diabetes + hypertension + smoking + Framingham score 10–20 %) | < 2.6 mmol/L (ESC/EAS 2019 guidelines) | < 1.8 mmol/L or reduction ≥ 50 % |
| Very high cardiovascular risk (secondary prevention post-MI + post-stroke + known coronary heart disease + peripheral artery disease) | < 2.2 mmol/L (ESC/EAS 2019 + SCC 2021 guidelines) | < 1,4 mmol/L ou réduction ≥ 50 % (lignes directrices ESC/EAS 2019) |
| Type 2 diabetes with target organ damage or multiple risk factors | < 2.2 mmol/L, non-HDL-C is the preferred marker in diabetes because TG-rich remnant lipoproteins are particularly atherogenic in this context | < 1.4 mmol/L according to ESC/EAS 2019 for very high-risk diabetics |
| Nephrotic syndrome + chronic kidney disease | < 2.6 mmol/L, non-HDL-C is preferred because LDL-C is often underestimated by the Friedewald formula in these contexts (frequent hypertriglyceridemia). | < 1.8 mmol/L or individualize based on renal function |
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The relationship between non-HDL-C and LDL-C is simple and constant: the non-HDL-C target is always equal to the LDL-C target + 0.8 mmol/L. Thus, if the LDL-C target is 1.8 mmol/L, the corresponding non-HDL-C target is 2.6 mmol/L. This 0.8 mmol/L difference corresponds to the fraction of cholesterol contained in VLDL with normal triglyceride levels (triglycerides × 0.44). This simple rule allows for the interchangeable use of LDL-C or non-HDL-C depending on the clinical context and the availability of fasting samples.
Advantages of non-HDL-C over calculated LDL-C
| Clinical situation | LDL-C Limit (Friedewald Formula) | Advantages of non-HDL-C |
|---|---|---|
| Hypertriglyceridemia (TG > 4.5 mmol/L) | The Friedewald formula (LDL-C = TC - HDL-C - TG/2.2) becomes invalid and massively underestimates the actual LDL-C when TG exceeds 4.5 mmol/L → many laboratories display «LDL-C not calculable» + cardiovascular risk underestimated | Non-HDL-C = TC − HDL-C → direct calculation + always valid regardless of triglyceride level + captures cholesterol from VLDL (elevated in hypertriglyceridemia) which then represent a significant part of residual atherosclerotic risk |
| Non-fasting blood draw | Friedewald's LDL-C is less reliable on a postprandial sample (increase in chylomicrons and VLDL which distort the calculation). | Non-HDL-C can be used on a non-fasting sample with acceptable reliability—recommended as a first-line parameter for non-fasting lipid profiles (SCC 2021 and ESC/EAS 2019 recommendations) |
| Type 2 diabetes and metabolic syndrome | LDL-C is often within normal limits or low in type 2 diabetes (characteristic lipid phenotype: high TG + low HDL + «normal» LDL-C but composed of small, very atherogenic dense particles = high LDL-P despite normal LDL-C). | Non-HDL-C captures the elevated VLDL and typical type 2 diabetes-associated atherogenic IDL → better prediction of residual cardiovascular risk + 2021 SCC guidelines recommend non-HDL-C as a priority target in diabetes |
| Patients on high-dose statins | Under high-dose statin therapy, LDL-C can reach very low values (< 0.5 mmol/L) where the Friedewald formula loses relative accuracy. Direct LDL-C (ultracentrifugation) or Nova LDL-C (Martin-Hopkins formula) are preferable. | Non-HDL-C remains reliable even at very low values, better reflects the persistence of residual risk related to TG-rich lipoproteins even when LDL-C is highly controlled, and allows for the detection of residual risk not captured by LDL-C in treated patients. |
| Chronic kidney failure + nephrotic syndrome | These conditions are accompanied by complex dyslipidemia with elevated VLDL + IDL + Lp(a) in addition to LDL → LDL-C alone underestimates the risk | Non-HDL-C captures all atherogenic lipoproteins increased in these conditions + recommended as a priority target in CKD according to the 2023 KDIGO guidelines. |
Interpretation of Non-HDL-C and Therapeutic Approach
- Calculation: non-HDL-C (mmol/L) = total cholesterol − HDL-C + available on any standard lipid panel without additional information + if not reported by the lab → manually calculable in 5 seconds from the standard lipid panel
- High non-HDL-C with normal LDL-C — clinical significance: common situation in diabetes + metabolic syndrome + hypertriglyceridemia + mixed hyperlipidemia (Fredrickson type III) + indicates an elevation of atherogenic non-LDL lipoproteins (VLDL + IDL + remnants) + cardiovascular risk underestimated if focus is solely on LDL-C + treatment: control of hypertriglyceridemia (weight loss + reduction of simple carbohydrates + alcohol + fibrates or omega-3 fatty acids if TG > 5.6 mmol/L) + statins to reduce the overall apoB burden
- High Non-HDL-C with High LDL-C: The most common situation in primary hypercholesterolemia and first-line treatment: effective dose statins. Statins reduce non-HDL-C by 30 to 55% pending on intensity. Ezetimibe is added if the target is not reached with statin alone (additional reduction of 15 to 20% %). PCSK9 inhibitors (evolocumab + alirocumab) are used if the target is not reached with high-dose statin + ezetimibe (additional reduction of 50 to 60% %).
- High non-HDL-C despite target LDL-C: residual risk related to remnant lipoproteins + mention untreated secondary hypertriglyceridemia (diabetes + hypothyroidism + obesity + alcohol + medications) + elevated Lp(a) (measure if suspected) + intensify lipid-lowering treatment or specifically target TG (fibrates + high-dose omega-3 fatty acids — icosapent ethyl Vascepa® which has demonstrated a 25% % reduction in cardiovascular events in the REDUCE-IT trial)
- Treatment follow-up : Lipid panel with non-HDL-C calculation 4 to 6 weeks after initiation or modification of lipid-lowering therapy, then annually if target is met, and at each cardiovascular follow-up visit for secondary prevention.
Non-HDL-C and apolipoprotein B (apoB)
Non-HDL-C and apolipoprotein B (apoB) are two complementary ways to quantify the atherogenic lipoprotein burden. Their comparison illuminates the strengths and limitations of each:
- ApoB measures the number of atherogenic particles. each non-HDL lipoprotein (LDL + VLDL + IDL + Lp(a)) contains exactly one molecule of apoB-100 → apoB concentration directly reflects the total number of circulating atherogenic particles + particularly superior to LDL-C and non-HDL-C when LDLs are small and dense (as in diabetes) because small LDL contain little cholesterol but as much apoB as a large LDL → LDL-C then underestimates the risk + normal apoB value: < 0.9 g/L (intermediate risk) + < 0.8 g/L (high risk) + < 0.7 g/L (very high risk)
- Non-HDL-C measures the mass of atherogenic cholesterol. reflects the amount of cholesterol carried in atherogenic lipoproteins + less direct than apoB for patients with small dense LDL + advantage: available on any standard lipid panel without additional testing + immediate calculation + the two markers are strongly correlated (r = 0.87) + in current practice, non-HDL-C is preferred for its simplicity and universal availability; apoB is used as a second-line option or for complex cases
- Discordant situation: low LDL-C / high non-HDL-C / high apoB: Typical phenotype of type 2 diabetes with small dense LDL + apoB and non-HDL-C detect residual cardiovascular risk that LDL-C alone misses + the 2021 SCC guidelines recommend measuring apoB in case of discordance between LDL-C and non-HDL-C or estimated global clinical risk
Situations Requiring Prompt Medical Attention
An non-HDL-C level above 5.0 mmol/L found on a lipid panel, especially if accompanied by very high total cholesterol, tendinous xanthomas, corneal arcus before age 40, or a family history of early cardiovascular disease (heart attack or stroke before age 55 in a man or 65 in a woman in a first-degree relative), should lead to a rapid medical evaluation to rule out familial hypercholesterolemia—an underdiagnosed but common genetic disease (1 in 250 people) that increases the risk of heart attack before age 50 by 20 times if untreated and benefits from early intensive lipid-lowering treatment.
For the interpretation of a lipid profile with non-HDL-C calculation, the assessment of overall cardiovascular risk, and the initiation or adjustment of lipid-lowering treatment, Clinique Omicron offers medical consultations at its service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's physician assistants (PAs) and nurse practitioners (NPs) interpret comprehensive lipid panels, including non-HDL-C, assess global cardiovascular risk (Framingham score + presence of diabetes + hypertension + smoking + family history), initiate and adjust lipid-lowering treatments (statins + ezetimibe + PCSK9 inhibitors according to indications and RAMQ coverage), and ensure therapeutic targets for lipids are met in primary and secondary prevention. Consultations are available at several service points across Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not replace the advice of a physician or cardiologist. Decisions regarding lipid targets and lipid-lowering therapy should be individualized according to each patient's overall cardiovascular risk profile, under medical supervision.
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