ANTIPLATELET ANTIBODY TESTING IN THROMBOCYTOPENIC PREGNANT-WOMEN

OBJECTIVE: The purpose of the study was to attempt to distinguish preg nant women with gestational thrombocytopenia from those with idiopathi c immune thrombocytopenia by eight different platelet antibody assays. STUDY DESIGN: Sera from pregnant women with presumed gestational thro mbocytopenia (n = 160) and idiopathic immune thrombocytopenia (n = 90) were prospectively tested for indirect and platelet-associated immuno globulins G and M and complement C3, as well as for serotonin release. After the results were analyzed, a subset of patients were subsequent ly analyzed for circulating antiplatelet antibody directed against pla telet membrane glycoprotein GPIIb/IIIa. RESULTS: Indirect immunoglobul in G was significantly greater in the 85 women with idiopathic immune thrombocytopenia than in the 129 women with gestational thrombocytopen ia (p < 0.001). Platelet-associated immunoglobulin G was elevated in t he majority of women, both those with gestational thrombocytopenia and those with idiopathic immune thrombocytopenia. There were also no sta tistically significant differences in the values for platelet-associat ed C3 or indirect immunoglobulin M and C3. Levels of platelet-associat ed immunoglobulin M showed a tendency to be higher in women with gesta tional thrombocytopenia (p = 0.04), as did the values in the serotonin release assay (p = 0.06). CONCLUSION: Our data demonstrate that patie nts with gestational thrombocytopenia had surprisingly high levels of platelet-associated immunoglobulin despite mild thrombocytopenia. Comp arison of a relatively large number of patients with idiopathic immune thrombocytopenia and gestational thrombocytopenia indicates that wome n with idiopathic immune thrombocytopenia cannot be distinguished from those with gestational thrombocytopenia by means of one or more of th e prototypic platelet antiglobulin tests currently in use. Our prelimi nary data with glycoprotein-specific assays indicate that they may be more useful.