Hemolysis + thrombosis (DVT) + pancytopenia; dark morning urine
Most accurate: Flow cytometry — CD55 / CD59 deficient
Treat: Eculizumab — or ravulizumab (long-acting C5, q8 wk, often preferred) — vaccinate against meningococcus first; pegcetacoplan (C3 inhibitor) an option for breakthrough hemolysis; anticoagulate thrombosis
Cure: Bone marrow transplant
Order set
- Flow cytometry (CD55/CD59)
- FBC, LDH
- Reticulocytes
- Screen for thrombosis
Criteria
AdmitThrombosis or marrow failure
ICUMajor thrombosis
DischargeComplement inhibitor plan, anticoagulation, haematology
Clinical detail — differentials, red flags, pitfalls, disposition
Red flags
- Thrombosis (atypical sites)
- Marrow failure
Common mistakes
- Missing thrombophilia link
- Not vaccinating before eculizumab
Disposition & follow-up
Complement inhibitor; anticoagulate thrombosis; transplant if marrow failure.
Discharge package
MedicationsComplement inhibitor; anticoagulation if thrombosis
Follow-upHaematology
VaccinationMeningococcal before eculizumab
Warning symptomsThrombosis symptoms, dark urine, infection
💊 Treatment detail — doses & preparation
Eculizumabcomplement C5 inhibitor
DosePNH/aHUS: 600 mg IV weekly ×4 → 900 mg at wk 5 → 900 mg q2 wk
Preparation300 mg vials dilute to 5 mg/mL, infuse 25–45 min
MonitorMENINGOCOCCAL vaccination ≥2 wk before first dose (± antibiotic cover); infection vigilance
Meningococcal vaccinationsafety
DoseACWY + B vaccines ≥2 wk before first eculizumab dose (± antibiotic cover)
PreparationPer national schedule
MonitorMeningococcal infection vigilance lifelong on drug
ApixabanDOAC (anti-Xa)
Dose5 mg BD (2.5 mg BD if ≥2 of: age ≥80, weight ≤60 kg, Cr ≥133). PE/DVT: 10 mg BD ×7 d then 5 mg BD
Preparation2.5/5 mg tablets (crushable)
MonitorBleeding, renal function; no routine monitoring
📖 BSH PNHReviewed July 2026