IgIV Plus Prednisone vs High-dose Dexamethasone for ITP

Inclusion Criteria: * Age ≥ 18 years ≤ 80 years * Diagnosis of ITP whatever the duration of the disease (newly diagnosed or relapsed) according to the standard definition * Platelet count ≤ 20 x 109/L * Any cutaneous and/or any mucosal bleeding manifestations * Affiliated to a social security regime * Written consent from patient Exclusion Criteria: * Symptomatic COVID-19 disease * Life-threatening bleeding defined as Intracranial hemorrhage and/or active organ bleeding (GI tract, urinary tract or menorrhagia with at least a 2 g/dl decrease of hemoglobin value from baseline). * Ongoing anticoagulation treatment (Therapeutic Low molecular weight heparins (LMWHs), direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs)) * Previous non-response to IVIg or DEX * Treatment with prednisone (1 mg/kg per day) for more than 3 days * Any, contraindications to the prescribed Ig IV or prednisone patent medicine and to Neofordex® * Ongoing severe infection * Severe Renal insufficiency (DFG \< 45 ml.min.1.73m2) * Severe Cardiac insufficiency (FEVG \< 30 %) * Ongoing viral infection (uncontrolled HIV, Viral hepatitis, herpes, varicella, zona). * Uncontrolled diabetes (Acido-cetosis) * Psychotic state not yet controlled by treatment * Inability or refusal to understand or refusal to sign the informed consent from study participation * Persons deprived of their liberty by judicial or administrative decision, * Persons under legal protection (guardianship, curatorship) * Pregnant or breastfeeding woman or ineffective contraception * Participation in another interventional study involving human participants or being in the exclusion period at the end of a previous study involving human participants.