Faster Diagnosis of TTP Using New Technoscreen Adamts-13 Activity Assay

Background

The thrombocytopenic purpura (TTP) is a life-threatening condition characterized by microvascular thrombosis where it is of great importance to shorten the time to the treatment. TTP can be caused by congenital or acquired deficiency of ADAMTS13 (an enzyme that cleaves the von Willebrand factor). Deficiency leads to the accumulation of ultra-large von Willebrand multimers, which causes platelet aggregation and the formation of microthrombi. TTP laboratory findings include thrombocytopenia, hemolytic anemia, the presence of schistocytes and a markedly reduced activity of ADAMTS13. ADAMTS13 activity can be analyzed using an ELISA method. We have evaluated whether a new semi-quantitative method, TECHNOSCREEN from Technoclone, can be used as a screening method to shorten the time for patient diagnosis.

Method

We analyzed 43 unidentified samples with known ADAMTS 13 activity, which consisted of 20 samples with an ADAMTS13 activity <10%. The new screening method (TECHNOSCREEN ADAMTS13 Activity) was compared to the existing ELISA method (TECHNOZYM ADAMTS13 Activity ELISA). Both methods were from Technoclone, Vienna, Austria. The methods are based on incubating patient plasma with von Willebrand fragments and specific antibodies to cleavage fragment. Color intensity correlates with the amount of cleavage and thus ADAMTS13 activity of the sample. In the screening method, color development takes place in a flow through test device and is semi-quantitatively graded by visual comparison against a color chart graded as 0.0, 0.1, 0.4 and 0.8 IU /mL.

Results and conclusion

The results showed good agreement between the existing ELISA and the newTECHNOSCREEN method. Sensitivity was 100% and specificity 71% if the ELISA is used as a gold standard. In May 2019, the TECHNOSCREEN method was introduced as a first-line analysis. This has resulted in faster patient diagnosis as well as saving laboratory staff time. The TECHNOSCREEN assay takes about 1 hour to perform compared to about 5 hours for the ELISA. To exactly quantify ADAMTS13 activity or detect the presence of antibodies, the ELISAs are performed approximately once a week.