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Clinical features and outcomes in patients with thrombotic microangiopathy not associated with severe ADAMTS13
Ang Li1,2, Pavan K Bendapudi2,3,4, Lynne Uhl2,5
1Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.
Background:
The a disintegrin and metalloprotease with thrombospondin type 1 motifs, member 13 (ADAMTS13) activity assay has become important in distinguishing autoimmune thrombotic thrombocytopenic purpura from other forms of thrombotic microangiopathy (TMA). Although the significance of severe deficiency in ADAMTS13 (activity levels 10% or less) has been well defined, little data are available on the clinical importance of mild to moderate deficiency (activity levels 11%-70%) among patients with TMA.
Study Design And Methods:
We conducted a retrospective study using the Harvard TMA Research Collaborative Registry. Among 254 patients who met the inclusion criteria for TMA, 186 patients with ADAMTS13 activity levels greater than 10% were divided into moderate-deficiency (11%-40%), mild-deficiency (41%-70%), and no-deficiency (greater than 70%).
Results:
Compared with mild or no deficiency, moderate ADAMTS13 deficiency correlated with older age; higher bilirubin and international normalized ratio; and increased frequency of sepsis, shock, or multiorgan failure. Platelet counts, lactate dehydrogenase levels, and the presence of renal or neurologic dysfunction did not vary across the three patient cohorts. While moderate ADAMTS13 deficiency was associated with increased 90-day mortality in univariate analysis, this association was no longer significant in multivariate analysis. Variables that independetly predicted 90-day mortality in this cohort of patients included Charlson comorbidity index, alanine aminotransferase level, platelet count, creatinine, and the presence of sepsis, shock, or multiorgan failure.
Conclusion:
Moderately deficient ADAMTS13 activity identifies a cohort of patients with TMA who are at increased risk for 90-day mortality. The ADAMTS13 activity level in this group is not an independent predictor of poor outcomes but instead appears to be a marker of disease acuity.
Insights
Moderate deficiency in ADAMTS13 activity (11%-40%) is linked to increased disease severity and 90-day mortality risk in thrombotic microangiopathy (TMA) patients. This deficiency serves as a marker for disease acuity rather than an independent predictor of outcomes.
Area of Science:
- Hematology
- Internal Medicine
- Clinical Pathology
Background:
- ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motifs, member 13) activity assays are crucial for differentiating autoimmune thrombotic thrombocytopenic purpura (TTP) from other thrombotic microangiopathies (TMAs).
- While severe ADAMTS13 deficiency (≤10% activity) is well-characterized, the clinical significance of mild to moderate deficiency (11%-70% activity) in TMA patients remains less understood.
Purpose of the Study:
- To investigate the clinical importance and prognostic implications of mild to moderate ADAMTS13 deficiency in patients with thrombotic microangiopathy (TMA).
- To identify patient characteristics and outcomes associated with varying levels of ADAMTS13 activity.
Main Methods:
- A retrospective study was conducted using the Harvard TMA Research Collaborative Registry.
- 186 TMA patients with ADAMTS13 activity >10% were categorized into moderate (11%-40%), mild (41%-70%), and no deficiency (>70%) groups.
Main Results:
- Moderate ADAMTS13 deficiency correlated with older age, higher bilirubin and INR, and increased frequency of sepsis, shock, or multiorgan failure.
- Platelet counts, LDH, and renal/neurologic dysfunction did not differ significantly across groups.
- Univariate analysis showed increased 90-day mortality with moderate deficiency, but this was not significant in multivariate analysis.
Conclusions:
- Moderately deficient ADAMTS13 activity identifies TMA patients at higher risk for 90-day mortality.
- ADAMTS13 activity level in this context acts as a marker of disease acuity, not an independent predictor of poor outcomes.
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