Hidden in plain sight: Recognizing TTP in the emergency department

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening thrombotic microangiopathy characterized by thrombocytopenia, microangiopathic hemolytic anemia, neurologic symptoms, renal dysfunction, and fever. Often patients present with only a subset of these abnormalities, many of which are present in other conditions, posing difficulty in the diagnosis. This diagnostic difficulty is compounded in the elderly and those with comorbidities who have varying clinical presentations. Early recognition and diagnosis are imperative as early treatment with plasmapheresis significantly improves outcomes. We present the case of a 58-year-old female with a history of recent cerebrovascular accident (CVA), diabetes, hypertension, and psychiatric illness, who presented with acute change in mental status. Her confusion was attributed to a urinary tract infection and her chronic neuropsychiatric conditions. Further laboratory evaluation revealed severe thrombocytopenia, elevated lactate dehydrogenase, low haptoglobin, and schistocytes on peripheral smear, raising concern for TTP. The patient was initiated on plasmapheresis, and the diagnosis of TTP was subsequently confirmed via ADAMTS13 testing. This case highlights the diagnostic challenge of a patient with overlapping comorbidities that may contribute to a change in mental status, masking the underlying diagnosis of TTP. The rapid identification and early initiation of plasmapheresis prevented further organ damage, improved prognosis, and provided a favorable outcome. This underscores the importance of maintaining a broad differential for patients presenting with altered mental status and remaining conscious of bias and anchoring in these patients with comorbid conditions when alternative explanations exist.