Athrombocytopenic thrombotic microangiopathy, a condition that could be overlooked based on current diagnostic criteria

BACKGROUND Thrombotic thrombocytopenic purpura (TTP) and haemolytic uraemic syndrome (HUS) are thrombotic microangiopathies (TMAs). They are generally diagnosed and treated by plasmapheresis in the presence of non-immune haemolytic anaemia and thrombocytopenia. Yet, many individuals admitted in our hospital for athrombocytopenic renal failure of unknown cause were reported to have TMA as main lesion on kidney biopsies. METHODS Speculating that this presentation is not uncommon and that the underlying lesion might not be suspected because of current diagnostic criteria, we determined its prevalence and other accompanying features through a retrospective single-centre cohort of 50 cases where TMA had been identified histologically. RESULTS At presentation, normal serum platelets were common (44%) but still accompanied by abnormal serum LDH in most subjects. End-stage renal disease and mortality at 5 years were also high especially in the athrombocytopenic group, but unrelated to the underlying aetiology of TMA. Importantly, several subjects in both groups received and apparently responded to plasmapheresis. CONCLUSION In the absence of thrombocytopenia, TMA should still be contemplated when renal failure is associated with high serum LDH and its possible treatment with plasmapheresis assessed through prospective trials.