ADAMTS-13 antigen and activity levels in thrombocytopenic disorders including thrombotic thrombocytopenic purpura in Kuwait.

Background/aims: While deficiency of a disintegrin and metalloprotease with thrombospondin-1-like domains (ADAMTS-13) was reported as the basis for the pathogenesis of thrombotic thrombocytopenic purpura (TTP), low levels have also been found in other thrombocytopenic disorders. This study was conducted to characterize the activity and antigen levels of ADAMTS-13 and von Willebrand factor (vWF) in patients with different thrombocytopenic disorders in Kuwait.

Methods: Forty healthy subjects and 41 patients with different thrombocytopenic disorders were recruited for this study. ELISA tests were used to measure ADAMTS-13 and vWF activity and antigen levels in patients and controls.

Results: All TTP patients had severely deficient ADAMTS-13 activity (<5%), which was significantly lower than that of controls (p < 0.001). Severe deficiency of ADAMTS-13 was also found in some, but not all, patients with idiopathic thrombocytopenic purpura, acute leukemia and sepsis.

Conclusions: This study is the first to report ADAMTS-13 levels in this part of the world. ADAMTS-13 was found to be severely deficient in TTP patients. We present evidence that significantly lower levels of ADAMTS-13 were not specific for TTP and can be found in other thrombocytopenic disorders. We also hypothesize that clinical manifestation of TTP may not be solely due to ADAMTS-13 deficiency, and there might be other contributing factors, since the deficiency was also found in some healthy controls.