Thrombotic microangiopathy
Comprehensive testing to confirm diagnosis and facilitate treatment
Thrombotic microangiopathy (TMA) is a heterogenous group of rare disorders characterized by thrombocytopenia and microangiopathic hemolytic anemia, and end organ damage that can occur due to ischemic injury of organs, such as renal injury or stroke. Thrombotic microangiopathies include the following diagnoses:
Because of the variety of TMA disorders and different treatment options for each, prompt and accurate diagnosis can significantly impact a patient’s outcome.
Optimizing treatment for challenging conditions
Plasma exchange — the treatment of choice for iTTP patients — has been shown to reduce morbidity from around 90% to less than 20%. TTP may be confirmed with ADAMTS13 activity and inhibition studies.
Patients diagnosed with STEC-HUS benefit from early supportive interventions. Intravenous volume expansion can potentially decrease renal damage. Antibiotics, which can cause the release of toxins, are to be avoided.
Management of TMA associated with other secondary causes involves identifying and treating the underlying cause. Medication-induced TMA is initially managed by withdrawing the causative medication. The diagnosis of aHUS, which is caused by a dysregulation of the complement alternative pathway, is one of exclusion. Complement serologic and genetic testing are useful to support a clinical diagnosis of aHUS, and management of the condition includes complement inhibition with medications such as eculizumab and ravulizumab.
Key testing
ADM13 | ADAMTS13 Activity and Inhibitor Profile, Plasma
Useful for:
AHUSD | Atypical Hemolytic Uremic Syndrome Complement Panel, Serum and Plasma
Panel uses several testing methods, including nephelometry, automated liposome lysis assay, and enzyme-linked immunosorbent assay (ELISA) to evaluate complement components for identification of the underlying cause of TMA.
Useful for:
Panel uses next-generation sequencing to evaluate 13 genes — ADAMTS13, C3, CD46 (MCP), CFB, CFD, CFH, CFHR1, CFHR3, CFHR5, CFI, DGKE, PLG, THBD — for complement function, complement component construction, and activation products.
Useful for:
ECULI | Eculizumab, Serum
This test uses liquid chromatography-tandem mass spectrometry (LC-MS/MS) to assess patient response to eculizumab therapy and monitor levels of medication concentrations to optimize therapeutic response.
Useful for:
Thrombotic Microangiopathies (TMA)
Meera Sridharan, M.D., Ph.D., explains Mayo Clinic Laboratories’ testing approach for atypical hemolytic uremic syndrome (aHUS). The serological complement panel examines nine analytes to gain a thorough understanding of the complement cascade to confirm diagnosis and direct care.