PLAC Activity Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is PLAC Activity?

PLAC activity refers to the enzymatic activity of lipoprotein-associated phospholipase A2 (Lp-PLA2), also known as platelet-activating factor acetylhydrolase (PAF-AH). This enzyme is primarily produced by macrophages, monocytes, and T-lymphocytes — key cells of the immune and inflammatory system. It circulates in the blood bound predominantly to LDL cholesterol particles.

Lp-PLA2 plays a specific role in vascular inflammation and atherosclerosis. It cleaves oxidised phospholipids on LDL particles within the arterial wall, generating two highly inflammatory mediators: lysophosphatidylcholine (lysoPC) and oxidised non-esterified fatty acids (oxNEFA). These products promote endothelial dysfunction, attract more inflammatory cells into the arterial wall, and destabilise atherosclerotic plaques — making them more prone to rupture and cause acute cardiovascular events such as heart attack or stroke.

Unlike general inflammatory markers such as C-reactive protein (CRP), which reflect systemic inflammation from any source (infection, autoimmune disease, injury), PLAC activity is considered a vascular-specific inflammatory marker. Elevated PLAC activity indicates that active inflammation is occurring within the arterial walls themselves, providing unique prognostic information about cardiovascular risk that complements traditional risk factors and lipid measurements.

The PLAC test measures the enzymatic activity of Lp-PLA2, reported in nanomoles per minute per millilitre (nmol/min/mL). An older version of the test measured Lp-PLA2 mass concentration (ng/mL), but activity measurement is now preferred due to better correlation with cardiovascular outcomes.

Why Is PLAC Activity Tested?

PLAC activity testing is used to refine cardiovascular risk assessment beyond standard lipid profiles. Key indications include:

• Intermediate cardiovascular risk: Patients classified as intermediate risk by standard tools (such as QRISK3) may benefit from PLAC testing to determine whether they should be reclassified to a higher risk category warranting more aggressive prevention.
• Assessing residual vascular risk: Patients already on statins with well-controlled LDL cholesterol may still have elevated PLAC activity, indicating ongoing vascular inflammation and residual risk despite treatment.
• Stroke risk assessment: Lp-PLA2 has been specifically associated with ischaemic stroke risk. The PLAC test is FDA-approved in the United States as a marker of stroke and coronary heart disease risk.
• Metabolic syndrome and diabetes: Patients with insulin resistance and type 2 diabetes often have elevated Lp-PLA2, contributing to their excess cardiovascular morbidity.
• Family history of cardiovascular disease: If conventional risk factors do not fully explain a strong family history of heart attack or stroke, PLAC activity may reveal underlying vascular inflammation.
• Monitoring anti-inflammatory interventions: PLAC activity can be used to assess the effect of dietary changes, statin therapy, and other interventions on vascular inflammation.
• Complementing other advanced markers: PLAC activity provides independent prognostic information when combined with hs-CRP, Lp(a), coronary artery calcium scoring, and carotid intima-media thickness.

Normal Ranges

PLAC activity is measured in nanomoles per minute per millilitre (nmol/min/mL). The following table outlines commonly used thresholds:

PLAC Activity (nmol/min/mL)	Risk Category	Interpretation
< 123 nmol/min/mL	Low risk	Normal vascular inflammatory activity
123–155 nmol/min/mL	Borderline risk	Mildly elevated; optimise modifiable risk factors
156–200 nmol/min/mL	Moderate risk	Elevated vascular inflammation; enhanced prevention recommended
> 200 nmol/min/mL	High risk	Significantly elevated; aggressive cardiovascular risk management

The commonly cited cut-off of 200 nmol/min/mL identifies individuals at approximately double the risk of coronary events compared to those with values below 123 nmol/min/mL. These thresholds are derived from large prospective studies including the ARIC (Atherosclerosis Risk in Communities) study and the MESA (Multi-Ethnic Study of Atherosclerosis) cohort.

What Do High PLAC Activity Levels Mean?

Elevated PLAC activity indicates active vascular inflammation and increased risk of atherosclerotic events. Associated conditions include:

• Active atherosclerosis: The most clinically significant finding. High PLAC activity reflects ongoing inflammatory processes within atherosclerotic plaques, indicating plaques that are more likely to be "vulnerable" or rupture-prone.
• Unstable angina and acute coronary syndromes: PLAC activity tends to be higher in patients with unstable (as opposed to stable) coronary artery disease, consistent with its role as a marker of plaque instability.
• Recent or impending ischaemic stroke: Elevated Lp-PLA2 is an independent predictor of ischaemic stroke, particularly large-artery atherosclerotic stroke.
• Metabolic syndrome: Insulin resistance, central obesity, and dyslipidaemia are associated with elevated PLAC activity.
• Type 2 diabetes: Diabetic patients frequently have raised Lp-PLA2, contributing to their elevated cardiovascular mortality.
• Familial hypercholesterolaemia: The high LDL burden in FH provides more substrate for Lp-PLA2, often resulting in elevated activity.
• Chronic kidney disease: CKD is associated with vascular inflammation and elevated PLAC activity, contributing to the high cardiovascular mortality in this population.
• Smoking: Current smokers tend to have higher Lp-PLA2 activity, reflecting smoking-induced vascular inflammation.

What Do Low PLAC Activity Levels Mean?

Low PLAC activity is generally favourable from a cardiovascular perspective:

• Low vascular inflammation: A PLAC activity below 123 nmol/min/mL indicates minimal inflammatory activity within the arterial walls. This is the desirable result.
• Effective statin therapy: Statins reduce Lp-PLA2 activity by approximately 20–35%, partly through LDL lowering (less substrate for the enzyme) and partly through direct anti-inflammatory effects. A low PLAC activity on statin therapy is reassuring.
• Healthy lifestyle: Regular exercise, a Mediterranean-style diet, non-smoking status, and healthy body weight are all associated with lower PLAC activity.
• Genetic variation: Some individuals have genetically lower Lp-PLA2 activity. In East Asian populations, a loss-of-function variant (V279F) in the PLA2G7 gene is relatively common, resulting in reduced or absent Lp-PLA2 activity.
• Anti-inflammatory medication effects: Certain drugs, including statins, fibrates, and some newer anti-inflammatory therapies, can lower PLAC activity.
• Low LDL cholesterol: Since Lp-PLA2 circulates bound to LDL, very low LDL levels (whether natural or treatment-induced) are associated with lower measured PLAC activity.

How to Improve Your PLAC Activity Levels

Reducing elevated PLAC activity involves targeting vascular inflammation and its underlying drivers:

Lifestyle Interventions

• Mediterranean diet: Rich in olive oil, oily fish, fruits, vegetables, wholegrains, nuts, and legumes. This dietary pattern has been shown to reduce vascular inflammation and improve multiple cardiovascular risk markers. The PREDIMED trial demonstrated significant cardiovascular benefit from a Mediterranean diet supplemented with extra virgin olive oil or nuts.
• Regular exercise: At least 150 minutes of moderate-intensity aerobic exercise per week reduces vascular inflammation. Aim for brisk walking, cycling, swimming, or similar activities.
• Smoking cessation: Stopping smoking reduces vascular inflammation within weeks and significantly lowers PLAC activity over time.
• Weight management: Losing 5–10% of body weight in overweight individuals can improve Lp-PLA2 levels alongside other inflammatory markers.
• Omega-3 fatty acids: EPA and DHA from oily fish or supplements have anti-inflammatory properties that may help reduce PLAC activity.

Medical Management

• Statin therapy: Statins are the most effective pharmacological intervention for reducing PLAC activity, achieving reductions of 20–35%. High-intensity statins (atorvastatin 40–80 mg, rosuvastatin 20–40 mg) produce greater reductions.
• Optimise LDL cholesterol: Lower LDL means less substrate for Lp-PLA2 to bind to and act upon. Ezetimibe and PCSK9 inhibitors provide additional LDL reduction.
• Blood pressure control: Hypertension contributes to endothelial injury and vascular inflammation. NICE targets of below 140/90 mmHg (or 130/80 mmHg for high-risk patients) should be achieved.
• Glycaemic control: In diabetic patients, optimising HbA1c reduces vascular inflammation.
• Aspirin: Low-dose aspirin may be recommended for secondary prevention in patients with established cardiovascular disease.

When Should You Get Tested?

Consider a PLAC activity test if:

• Your QRISK3 score places you in an intermediate risk category (10–20% ten-year risk) and you want additional information to guide treatment decisions.
• You have a strong family history of heart attack or stroke not fully explained by conventional risk factors.
• You are on statin therapy and want to assess residual vascular inflammatory risk.
• You have type 2 diabetes or metabolic syndrome and want a more detailed cardiovascular assessment.
• You have had a transient ischaemic attack (TIA) or minor stroke and want to assess your risk of recurrence.
• Your hs-CRP is elevated and you want a vascular-specific inflammation marker to complement it.
• You want a comprehensive, advanced cardiovascular risk profile beyond standard lipid testing.

Which Lola Health Tests Include PLAC Activity?

PLAC activity is an advanced cardiovascular biomarker that provides unique insight into vascular inflammation. Lola Health includes it in our premium testing panels:

• Peak Insights — our most detailed health screen, featuring PLAC activity alongside a full lipid profile, Lp(a), hs-CRP, and over 50 other biomarkers for the most thorough cardiovascular risk assessment available.
• Vital Check — a thorough wellness panel covering cardiovascular, metabolic, and inflammatory health markers.
• Core Health — an essential health check providing key cardiovascular and metabolic insights.

All Lola Health tests use venous blood draws for clinical-grade accuracy. Your results are reviewed by qualified healthcare professionals who provide personalised recommendations for managing your cardiovascular risk.