A 58-year-old woman with multiple myeloma on daratumumab requires urgent blood transfusion. The blood bank reports panreactivity on crossmatching with all donor panels. The most appropriate next step is:
- A Request daratumumab interference evaluation using dithiothreitol-treated red cells before transfusing ✓
- B Treat with high-dose corticosteroids for autoimmune haemolytic anaemia
- C Discontinue daratumumab permanently and switch to bortezomib
- D Transfuse O-negative packed cells empirically without further workup
Correct answer: A. Request daratumumab interference evaluation using dithiothreitol-treated red cells before transfusing
Explanation
Daratumumab targets CD38, which is weakly expressed on red blood cells, so the drug coats recipient erythrocytes and causes apparent panagglutination during indirect antiglobulin testing. This is an analytic interference, not true autoimmunity. The standard solution is treating patient red cells with dithiothreitol (DTT), which strips CD38 and allows identification of underlying alloantibodies, or supplying phenotyped matched units from the time daratumumab is started. Steroids and drug withdrawal are unnecessary because haemolysis is not occurring.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.