For patients with symptomatic PNH (including hx of thrombosis, e/o ongoing hemolysis, etc) would recommend treatment with a complement inhibitor. Ravulizumab may be preferable to eculizumab given its comparable efficacy and toxicity, but greater convenience (less frequent dosing). Patients being treated w/ complement inhibition should be vaccinated and receive oral antibiotic ppx (penicillin VK). If there is significant or persistent breakthrough hemolysis while on ravulizumab (or eculizumab) would then add pegcetacoplan. If there have been any recent acute thrombotic events would also treat with anticoagulation (in additional to complement inhibition as above). In such patients would continue anticoagulation for 3-6 months w/ plan to discontinue if/when there is good response to anti-complement therapy (though duration of AC should be individualized based on other risk factors). For subclinical PNH (no significant hemolysis, no hx of thrombosis, no e/o bone marrow failure), could pursue watchful waiting alone rather than complement inhibition. Bone marrow examination should be pursued in all patients w/ c/f bone marrow failure/dysfunction (those with cytopenias besides hemolytic anemia alone, or those with unexplained anemia out of proportion to degree of hemolysis, or persistent unexplained anemia in spite of resolution of hemolysis). Those patients with evidence of severe aplastic anemia or moderate-to-high risk MDS who are medically fit for transplantation should be referred for allogeneic transplant evaluation (in addition to the other interventions discussed above). Patients with lower risk bone marrow dysfunction may be initially observed rather than referred for bone marrow transplantation (in addition to the other interventions described above).