A boy with joint pain associated with emicizumab treatment: The importance of plasma level measurement

F I G U R E 1 Pain episodes, emicizumab administrations (105 or 60 mg per dose) and emicizumab plasma levels (g/ml; left Y-axis) by date (dd-mm-yyyy) in our patient. Also are given: the inhibitor titre (BU; right Y-axis) and start immune tolerance induction (ITI). The numbers above the pain episodes indicate that an ultrasound investigation has been performed with as result: 1, normal; 2, <1 cm hematoma intraarticular upper leg/left knee; 3, 1 cm hematoma bursa retrocalcanea left ankle; 4, thickened fascia m masseter left jaw