Lipoprotein(a)
Lipid PanelWhat is Lipoprotein(a)?
Lipoprotein(a), or Lp(a), is a lipoprotein particle consisting of a low-density lipoprotein (LDL)-like moiety covalently bound to apolipoprotein(a), a unique glycoprotein that shares structural homology with plasminogen. Lp(a) is assembled in the liver and circulates in the blood at concentrations largely determined by the LPA gene on chromosome 6q25-26. Unlike other lipoproteins, Lp(a) levels are approximately 80–90% genetically determined and are relatively stable throughout adult life, unaffected by diet, exercise, or most standard lipid-lowering medications including statins.
Lp(a) is now recognized as an independent, causal risk factor for atherosclerotic cardiovascular disease (ASCVD), aortic valve stenosis, and ischemic stroke. Its pathogenicity stems from its dual nature: the LDL-like component contributes to cholesterol deposition in arterial walls, while the apolipoprotein(a) component has pro-inflammatory and antifibrinolytic properties (by competing with plasminogen for fibrin binding, it impairs clot dissolution). Approximately 20% of the global population has elevated Lp(a) levels (>50 mg/dL or >125 nmol/L), making it one of the most prevalent genetic risk factors for cardiovascular disease.
Why It Matters
Elevated Lp(a) confers a 2- to 3-fold increased risk of myocardial infarction, ischemic stroke, and aortic valve stenosis, independent of LDL cholesterol. Because Lp(a) is genetically determined and not lowered by lifestyle changes or statins, many patients with elevated Lp(a) have "residual risk" even when LDL cholesterol is well controlled. Identifying elevated Lp(a) allows for more aggressive management of modifiable risk factors. Additionally, Lp(a) contributes to the LDL cholesterol value measured on standard lipid panels—approximately 30% of the Lp(a) mass is cholesterol—meaning some patients thought to have high LDL actually have Lp(a)-driven elevation. Novel therapies specifically targeting Lp(a) (including antisense oligonucleotides and siRNA) are in late-stage clinical trials.
Normal Reference Ranges
| Group | Range | Unit |
|---|---|---|
| Desirable | <30 | mg/dL |
| Borderline risk | 30–50 | mg/dL |
| High risk | >50 | mg/dL |
| Desirable (SI units) | <75 | nmol/L |
| High risk (SI units) | >125 | nmol/L |
Reference ranges may vary by laboratory. Always compare results to the ranges provided by your testing facility.
What High Lp(a) Levels Mean
Common Causes
- Genetic (LPA gene variants—the primary determinant)
- African ancestry (higher median Lp(a) levels)
- Chronic kidney disease (reduced clearance)
- Nephrotic syndrome
- Hypothyroidism (modest increase)
- Menopause (estrogen withdrawal can increase Lp(a))
Possible Symptoms
- Elevated Lp(a) does not cause symptoms directly
- Premature coronary artery disease or heart attack
- Ischemic stroke, especially at a young age
- Aortic valve calcification and stenosis
- Family history of early cardiovascular events
What to do: There is currently no FDA-approved drug specifically targeting Lp(a), though clinical trials are underway. Management focuses on aggressive reduction of modifiable risk factors: treat LDL cholesterol to lower targets (consider PCSK9 inhibitors, which lower Lp(a) by ~20–30%), optimize blood pressure, manage diabetes, stop smoking, and maintain a healthy weight. PCSK9 inhibitors and niacin are the only available agents that modestly lower Lp(a). Lipoprotein apheresis is available in some countries for very high Lp(a) with progressive cardiovascular disease. Ensure family members are screened given the genetic nature.
What Low Lp(a) Levels Mean
Common Causes
- Genetic (LPA gene variants resulting in low production)
- Low Lp(a) is the normal, desirable state
Possible Symptoms
- No symptoms—low Lp(a) is associated with lower cardiovascular risk
What to do: Low Lp(a) is optimal and requires no intervention. It confers a lower risk of cardiovascular disease. No further testing or treatment is needed for low Lp(a) levels.
When Is Lp(a) Testing Recommended?
- At least once in every adult's lifetime for cardiovascular risk assessment (per European Atherosclerosis Society guidelines)
- When there is a family history of premature cardiovascular disease
- In patients with recurrent cardiovascular events despite optimal LDL control
- When aortic valve stenosis is diagnosed at a younger age
- In patients with familial hypercholesterolemia to refine risk
- When a first-degree relative is known to have elevated Lp(a)
Frequently Asked Questions
Related Biomarkers
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Upload Lab Results →Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation of your specific test results.