Background: A platelet kinetic study (PKS) is not indicated in the evaluation of adult patients with idiopathic thrombocytopenic purpura (ITP) at presentation. However, in ITP patients refractory to or relapsing after corticosteroid therapy, its appropriateness is considered uncertain.
Methods: We prospectively performed a PKS with (111)In oxine-labeled autologous platelets in 93 consecutive adult ITP patients failing steroid treatment.
Results: In 22 patients (24%) a primary condition accounting for thrombocytopenia was identified (17 with myelodysplastic syndrome and three aplastic anemia). Non-ITP patients had significantly longer platelet circulating life span (P=0.0001), lower splenic platelet uptake (P=0.008) and higher liver platelet uptake (P=0.05) compared to 71 patients with confirmed ITP. Among ITP patients with platelets persistently <50 x 10(9)/L, splenectomy was considered in 48 cases. In 23 (48%) it was prospectively excluded because of platelet life span > or = 7 days (11 cases), no splenic platelet uptake together with high liver uptake (10 cases), or both conditions (two cases). Splenectomy was successfully carried out in the other 25 patients, obtaining a response rate of 100% (22 complete responses; three partial responses). Persistent relapse occurred in six of 25 (24%) splenectomized patients after a median of three months (range 1-8). PKS parameters were not able to predict post-splenectomy relapse, although relapsed patients had lower splenic/hepatic platelet uptake ratio (2.6 in relapsed vs 4.9 in persistently responsive patients; P=0.08).
Conclusions: It was concluded that in patients with chronic ITP failing steroid therapy, some PKS parameters may be prospectively used to increase the short term success rate of splenectomy.