Thrombopoietin: a potential diagnostic indicator of immune thrombocytopenia in pregnancy.

To evaluate whether the serum thrombopoietin levels in pregnancy-associated immune thrombocytopenia (ITP) differ from those in gestational thrombocytopenia, and reveal the possibility of thrombopoietin serving as a marker for differential diagnosis. Serum thrombopoietin concentration was determined in ITP in pregnancy (n = 35), gestational thrombocytopenia (n = 31), healthy pregnancy (n = 32), age-matched nonpregnant ITP (n = 32) and nonpregnant healthy controls (n = 35) by ELISA. The serum thrombopoietin level of ITP in pregnancy (1283 ± 646 pg/mL) was significantly higher than gestational thrombocytopenia (187 ± 64 pg/mL) (P < 0.01), although the platelet counts of these two disorders may overlap. Twenty-nine of 35 patients with ITP in pregnancy had thrombopoietin values >500 pg/mL, whereas none of the gestational thrombocytopenia patients' thrombopoietin levels exceeded 500 pg/mL. In addition, ITP in pregnancy presented a markedly higher thrombopoietin level than nonpregnant ITP (88 ± 41 pg/mL) (P < 0.01), indicating that the pathogenesis of pregnant and nonpregnant ITP was different. Our findings suggest that measurement of serum thrombopoietin concentration provides valuable diagnostic information for differentiating ITP in pregnancy from gestational thrombocytopenia. Thrombopoietin represents a reliable marker for ITP in pregnancy.