Differential Analysis for Thrombotic Microangiopathy (TMA)
Facilitate prompt diagnosis and management of patients with TMA
Updated: December 2014
Published: September 2012
Management of TMA Patients
The large majority of congenital and idiopathic TTP patients initially present with thrombocytopenia and peripheral blood evidence of microangiopathy, and in the absence of any other potential explanation for such findings, satisfy criteria for early initiation of plasma exchange, which is critical for patient survival.
Plasma exchange is the treatment of choice for TTP and should be initiated even if there is some uncertainty about the diagnosis because it has been shown to reduce the TTP-associated mortality from around 90% to less than 20%.
The diagnosis of TTP may be confirmed with ADAMTS13 activity and inhibition studies. If an alternative condition is diagnosed, the role of plasma exchange can be re-evaluated depending on the underlying cause of the microangiopathy.
Patients who are diagnosed with STEC-HUS should be treated with intravenous volume expansion early in the infection to potentially decrease renal damage. In addition, antibiotics should be avoided because they could cause the release of toxins.
DIC and Other Secondary Causes
If congenital TTP, idiopathic TTP, and STEC-HUS are ruled out, based on other clinical indications, management for DIC or secondary TTP (usually the patient has >10% ADAMTS13 activity) would include finding and treating the underlying cause while managing the coagulopathy. Alternatively, aHUS management may include eculizumab, while therapy directed toward cancer would be appropriate for metastatic cancer patients.
Patients with aHUS will also benefit from complement testing. A classic pattern seen in aHUS patients is a low (near zero) functional activity of the alternative pathway of the complement system (AH50) with normal levels of complement component 4 (C4) and decreased complement factor B.