A cross-sectional study on thrombopoietin levels in immune thrombocytopenia and its correlation with platelet count, megakaryocytes, and treatment response

INTRODUCTION: Thrombopoietin (TPO) being the major regulator of megakaryopoiesis is expected to show a compensatory increase in immune thrombocytopenia (ITP), however, it is not so observed. This study was undertaken to measure TPO levels in ITP and assesses its association with platelet count, megakaryocytes, and response to steroid therapy. MATERIALS AND METHODS: A total of 41 cases of ITP and twenty controls with normal platelet count were enrolled in this prospective study. Complete blood count, bone marrow examination, and ELISA for serum TPO were measured. Response to steroid therapy was evaluated for thirty cases. RESULTS: The TPO levels were increased in 80.5% of patients in comparison to the controls. The degree of rise, however, was variable. On analyzing low, normal, and high TPO levels with reference to platelet and megakaryocyte count no statistically significant difference was observed. Raised TPO levels were seen with significant lowering of functional megakaryocytes. The mean TPO levels in nonresponders were higher than responders but highly variable and statistically nonsignificant. CONCLUSION: Quantitative alterations in TPO are in a way regulated by qualitative efficacy of megakaryocytes rather than platelet or megakaryocyte count. Nonresponders with markedly increased TPO levels (due to qualitative megakaryocyte injury) are less likely to respond to TPO receptor agonist.