Adalimumab as a potential cause of drug-induced thrombocytopaenic microangiopathy

We report the case of a 63-year-old male patient admitted to our emergency department for dyspnoea, peripheral oedema, severe diarrhoea and asthenia. History revealed Crohn's disease (CD) submitted to several intestinal surgical resections in the previous years. He recently started a treatment with adalimumab for the control of CD. Laboratory tests at the admission revealed severe haemolytic anaemia and thrombocytopaenia. Haptoglobin levels were low, schistocyte count was markedly increased. In the suspect of thrombotic microangiopathy, he was admitted to our internal medicine department where we urgently started plasma exchange (PEX). We observed normal ADAMTS-13 activity in absence of Shiga toxin or enterotoxic Escherichia c oli at stool tests. Despite a diagnosis of atypical haemolytic-uraemic syndrome, we observed full platelet count recovery and schistocytes normalisation after the fourth PEX. We then put a diagnosis of adalimumab-induced thrombocytopaenic microangiopathy. Adalimumab was withdrawn. We did not observe relapses in the following 3 months.