Enoxaparin (low-molecular-weight heparins) and Heparin-induced thrombocytopenia (HIT): is the FAERS signal real?
Enoxaparin (low-molecular-weight heparins) ↔ Heparin-induced thrombocytopenia (HIT)
Enoxaparin, like unfractionated heparin, can cause heparin-induced thrombocytopenia — an immune reaction in which antibodies activate platelets, dropping the platelet count and paradoxically promoting clotting. It is less common with low-molecular-weight heparins than with unfractionated heparin but is still a recognised and serious effect, and it is why platelet counts are watched during therapy and why a non-heparin anticoagulant is used if HIT is suspected. The 637 co-reports (PRR 54.1) reflect both the real effect and the very wide use of enoxaparin.
Regulatory basis: enoxaparin prescribing information (HIT warning; platelet monitoring). Established low-molecular-weight-heparin HIT literature.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Platelets fall days into exposure and recover after heparinoid withdrawal |
| Strength | met | PRR 54 on a moderate co-report count |
| Consistency | met | Reproduced across the heparinoid class |
| Specificity | met | A class effect, though less frequent than with unfractionated heparin |
| Biological gradient | partial | Risk varies with duration and patient group, not a simple dose gradient |
| Plausibility | met | Anti-PF4 antibody-mediated platelet activation is the mechanism |
| Coherence | met | Coheres with routine platelet monitoring during therapy |
| Experiment | partial | Dechallenge (switching to a non-heparin anticoagulant) is standard; no placebo RCT |
| Analogy | met | Analogous to HIT with unfractionated heparin and dalteparin |
This page's own qualitative read, not an automated/citation-gated assessment.