3
➤ Remarkable advances have been made in recent years towards our
understanding of the pathophysiology of thrombotic thrombocytopenic
purpura (TTP), which has led to advancements in novel therapies.
➤ Despite an increase in our understandings of pathogenesis of TTP, the
approaches for initial diagnosis and management of TTP vary significantly.
➤ The guidelines are intended to support patients, clinicians, and other
healthcare professionals in their decisions about the initial diagnosis
and management of acute TTP.
➤ In settings with timely access to plasma ADAMTS13 activity testing and
for patients with a high clinical suspicion of immune TTP (e.g., based on
clinical assessment or a formal clinical risk assessment method), the
panel suggests the following diagnostic strategies (See Table 1). (C-L)
Table 1. Diagnosis in settings with timely access to plasma
ADAMTS13 activity testing and for patients with a
HIGH clinical suspicion of immune TTP
Step 1. Acquire a plasma sample for ADAMTS13 testing (e.g. ADAMTS13 activity
and inhibitors or anti-ADAMTS13 IgG) before an initiation of therapeutic
plasma exchange (TPE) or use of any blood product.
Step 2. Start TPE and corticosteroids without waiting for the results of ADAMTS13
testing (see Recommendation 1 in Management Guidelines).
Step 3. Consider early administration of caplacizumab. (see Recommendation 5 in
Management Guidelines) before receiving ADAMTS13 activity results.
Step 4. When the result of plasma ADAMTS13 activity is available, continue
caplacizumab if ADAMTS13 activity is less than 10 IU/dL (or less than
10% of normal) (a positive result) or stop caplacizumab and consider other
diagnoses if ADAMTS13 activity is greater than 20 IU/dL (or greater than
20% of normal) (a negative result).
Step 5. For patients with plasma ADAMTS13 activity less than 10 IU/dL (or less
than 10% of normal) (a positive result), consider adding rituximab as early as
possible, as a majority of these patients (>95%) have autoantibodies against
ADAMTS13 (see Recommendation 2 in Management Guidelines).
Note: Clinical judgement is required for continuing or stopping treatments (e.g., TPE,
corticosteroids, rituximab, and caplacizumab, etc.) when plasma ADAMTS13 activity is
between 10 and 20 IU/dL (or 10-20% of normal) (an equivocal result).
Diagnosis
Key Points
