What is considered a normal Low-Density Lipoprotein (LDL) to High-Density Lipoprotein (HDL) cholesterol ratio?

Normal LDL to HDL Cholesterol Ratio

A normal LDL to HDL cholesterol ratio is generally considered to be below 3.5, with optimal cardiovascular health associated with ratios below 2.5. 1

Understanding LDL/HDL Ratio

The LDL/HDL ratio combines two important lipid parameters into a single metric that provides valuable information about cardiovascular risk:

• LDL cholesterol: The "bad" cholesterol that contributes to arterial plaque formation
• HDL cholesterol: The "good" cholesterol that helps remove excess cholesterol from the bloodstream

Clinical Significance

The ratio between atherogenic lipoproteins and HDL-C (including LDL/HDL ratio) has been used in large prospective studies as an indicator of cardiovascular risk 1. This ratio provides several advantages:

• Combines information about both atherogenic and protective lipoproteins
• May better predict cardiovascular risk than either parameter alone 2
• Particularly useful when assessing patients with mixed dyslipidemia

Interpretation of LDL/HDL Ratio Values

LDL/HDL Ratio	Risk Level
< 2.0	Optimal
2.0-2.5	Good
2.5-3.5	Average
3.5-5.0	High
> 5.0	Very high

Evidence Supporting LDL/HDL Ratio

Recent research demonstrates that the LDL/HDL ratio may be superior to either LDL-C or HDL-C alone in predicting coronary atherosclerotic heart disease (CAHD) 2. A 2022 study found:

• Higher LDL/HDL ratios in CAHD patients compared to controls (2.94 ± 1.06 vs. 2.36 ± 0.78)
• LDL/HDL ratio significantly associated with coronary vascular stenosis severity
• Better predictive value (AUC 0.668) compared to LDL-C alone (AUC 0.574) or HDL-C alone (AUC 0.625)
• A cut-off value of 2.517 with 65% sensitivity and 61% specificity

Clinical Application

When evaluating a patient's lipid profile:

1. Calculate the LDL/HDL ratio by dividing LDL-C by HDL-C
2. Interpret within context of other risk factors (age, smoking, hypertension, diabetes)
3. Consider treatment targets for both individual components:
   • LDL-C targets: <70 mg/dL for high-risk patients, <100 mg/dL for moderate-risk patients, <115 mg/dL for low-risk patients 3
   • HDL-C targets: >40 mg/dL for men, >50 mg/dL for women 3

Important Considerations

• While the LDL/HDL ratio provides valuable information, treatment decisions should focus on the individual components rather than the ratio itself 1
• The European Society of Cardiology guidelines note that ratios are useful for risk estimation, but for diagnosis and treatment targets, the components should be considered separately 1
• Some studies suggest that the complex interaction between LDL and HDL may not be fully captured by a simple ratio 4
• HDL functionality appears more important than HDL-C quantity for cardiovascular protection 3

Limitations

• The LDL/HDL ratio does not account for other important lipid parameters like triglycerides
• It may not fully reflect the heterogeneity of LDL and HDL particles (size, density, functionality) 5
• Very low LDL levels (<70 mg/dL) may still carry cardiovascular risk if HDL levels are also low 6

By monitoring both the individual lipid components and their ratio, clinicians can better assess cardiovascular risk and guide therapeutic interventions aimed at reducing that risk.