Normal Lipoprotein(a) Levels
Normal lipoprotein(a) [Lp(a)] levels are considered to be less than 30 mg/dL or less than 75 nmol/L, which represents values below the 75th percentile in white populations. 1, 2
Understanding Lipoprotein(a) Risk Categories
Lipoprotein(a) levels can be categorized into risk groups:
- Low risk: <75 nmol/L (<30 mg/dL)
- Intermediate risk: 75-125 nmol/L (30-50 mg/dL)
- High risk: ≥125 nmol/L (≥50 mg/dL) 2
These thresholds are based on epidemiological data that show increased cardiovascular disease (CVD) risk at levels above 30 mg/dL, with even greater risk at levels above 50 mg/dL.
Measurement Considerations
Lp(a) levels are primarily genetically determined and remain relatively stable throughout a person's lifetime. The National Lipid Association now recommends measuring Lp(a) at least once in every adult for cardiovascular risk stratification 2. This represents an evolution in clinical practice, as Lp(a) testing was previously recommended only in specific high-risk populations.
Population Variations
It's important to note that Lp(a) levels show significant variation across different ethnic groups:
- Approximately 20% of Caucasians have Lp(a) levels above 50 mg/dL
- African-Americans and Asian-Indians tend to have higher frequencies of elevated Lp(a) 3
Clinical Implications
Elevated Lp(a) is a causal risk factor for:
- Atherosclerotic cardiovascular disease
- Myocardial infarction
- Stroke
- Calcific aortic valve disease
- Heart failure
- Peripheral arterial disease 4, 3
Measurement Recommendations
Various guidelines recommend Lp(a) measurement in specific clinical scenarios:
- European Society of Cardiology/European Atherosclerosis Society: Patients with premature CVD, familial hypercholesterolemia, family history of premature CVD or elevated Lp(a), recurrent CVD despite optimal lipid-lowering therapy, or ≥5% 10-year risk of fatal CVD 1
- Canadian Cardiovascular Society: Similar indications with a cutoff of >30 mg/dL for abnormal levels 1
- National Lipid Association: Now recommends universal screening of all adults at least once 2
Important Clinical Caveat
A significant clinical challenge is that Lp(a) cholesterol content (30-45% of Lp(a) by mass) is included in standard LDL-C measurements. This means that in patients with elevated Lp(a), a portion of their measured "LDL-C" is actually coming from Lp(a), which may affect treatment decisions and goals 1. This becomes particularly important in patients with very low LDL-C levels, where the contribution of Lp(a) cholesterol to the measured LDL-C may be substantial.
Recognizing normal versus elevated Lp(a) levels is critical for cardiovascular risk assessment, as approximately one billion people globally have elevated Lp(a) levels, making it one of the most important genetically determined risk factors for cardiovascular disease 1, 3.