Lupus Anticoagulant (LAC) Reporting Framework

LAC Interface: Standardized reporting for dRVVT or SCT. Follows the ISTH algorithm: Screen-Mix-Confirm.

Test Metrics (seconds)

Screening Time

Mixing Time (1:1 with Normal)

Normal Pooled Plasma (NPP)

Confirmatory Step

High Phospholipid Time

Sustained correction by phospholipids confirms LAC.

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

Interpreting screening tests for Lupus Anticoagulant (LAC).

Applying the ISTH three-step algorithm (Screen → Mix → Confirm).

Differentiating LAC-mediated prolongation from coagulation factor deficiencies.

Patient Population

Patients with clinical suspicion of Antiphospholipid Syndrome (APS), unexplained prolongation of the aPTT, or recurrent pregnancy loss.

When Not to Rely on This Score Alone

Anticoagulant Therapy — Warfarin, DOACs, and Heparins can cause false-positive LAC results. Ideally, test when the patient is off anticoagulation (or use specialized procedures like Taipan Snake Venom Time).

Acute Phase — LAC testing should not be performed during an acute thrombotic event or inflammatory state.

Diagnosis of APS — requires persistence of the LAC for ≥ 12 weeks.

Last Comprehensive Review: 2026-07-17

In Recent Clinical News

Scanning Medical Journals

No new significant updates or guidelines matching this topic were found today. We will check again soon.

Lupus Anticoagulant (LAC) Reporting Framework

Test Metrics (seconds)

Confirmatory Step

When to Use

When to Use

Patient Population

When Not to Rely on This Score Alone

How it Works

Step 1: Screen (Prolongation)

Step 2: Mix (Correction failure)

Step 3: Confirm (Correction by PL)

Clinical Pearls

The dRVVT vs. aPTT

Index of Circulating Anticoagulant (ICA)

The Evidence

Guidelines

Update of the guidelines for lupus anticoagulant detection. Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies of the Scientific and Standardization Committee of the ISTH.

Origins & History

Definition

In Recent Clinical News

Lupus Anticoagulant (LAC) Reporting Framework

Test Metrics (seconds)

Confirmatory Step

When to Use

When to Use

Patient Population

When Not to Rely on This Score Alone

How it Works

Step 1: Screen (Prolongation)

Step 2: Mix (Correction failure)

Step 3: Confirm (Correction by PL)

Clinical Pearls

The dRVVT vs. aPTT

Index of Circulating Anticoagulant (ICA)

The Evidence

Guidelines

Update of the guidelines for lupus anticoagulant detection. Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies of the Scientific and Standardization Committee of the ISTH.

Origins & History

Definition

In Recent Clinical News