Mean platelet volume and platelet distribution width in the prediction of treatment response in immune thrombotic thrombocytopenic purpura with severe ADAMTS13 deficiency: a multicenter study

Aims:Lactate dehydrogenase (LDH) and platelet count are routinely used to evaluate response to treatment and discontinuation of treatment in thrombotic thrombocytopenic purpura (TTP). This study aimed to evaluate the mean platelet volume (MPV) and platelet distribution width (PDW) in immune TTP (iTTP) as markers of treatment response.Methods:This retrospective, multicenter study included patients diagnosed with iTTP with severe ADAMTS13 deficiency. We studied the correlations of MPV and PDW values with platelet count, LDH, total bilirubin hematocrit and mean corpuscular volume, which are used to evaluate the response to total plasma exchange (TPE) or relapse in iTTP. The study variables were recorded at the time of diagnosis, 1st week of TPE treatment, and the time of the last TPE. The correlation analyses were performed between the values before the initial TPE, and after the first week and last TPE.Results:The study included 28 patients, 20 females with iTTP [median age (minimum-maximum): 45 (23-74) years]. MPV correlated positively with LDH (r=0.533, p=0.002) and negatively with hematocrit (r=-0.445, p=0.002) and platelet count (r=-0.560, p=0.002). PDW also correlated positively with LDH (r=0.339, p=0.008) and negatively with hematocrit (r=-0.244, p=0.032) and platelet count (r=-0.285, p=0.022).Conclusions:The results showed that MPV and PDW correlated with LDH and platelet count, which are currently used to evaluate the response to treatment in iTTP. Changes in MPV and PDW may serve as a surrogate of treatment response in these patients as an indicator of response to plasmapheresis.