Clinical Study of Idiopathic Thrombocytopenic Purpura: Focused on Reticulated Platelet

Yun, Hwa Jun; Choi, Hee Weon; Park, Seok Won; Cha, Byung Ho; Kim, Hwang Min

Abstract

PURPOSE: Immune thrombocytopenic purpura (ITP) is divided into acute and chronic forms. Unfortunately, there have been no known specific laboratory or clinical predictors for the diagnosis of chronic ITP. This study was performed to elucidate the prognostic significance of various clinical and laboratory parameters, including reticulated platelet percentage.
METHODS
We retrospectively analyzed 60 patients who were diagnosed as ITP at the Department of Pediatrics, Wonju Christian Hospital from January, 1989 to January, 2001. Various kind of clinical parameters such as age, sex, symptom duration, prior URI history, response to treatment, and laboratory parameters like platelet count at initial presentation, lowest platelet count, duration of thrombocytopenia, initial reticulated platelet percentage, antiplatelet antibody IgG and IgM, antinuclear antibody (ANA), direct and indirect Coombs' test were compared between acute and chronic ITP.
RESULTS
Fifteen % of patients (9/60) was chronic ITP. The peak age incidence was from 1 to 3 year of age in both acute (29.4%) and chronic ITP (22.2%). The acute ITP was prevalent in spring season, May and June. There was no difference in the incidence of prior URI history between acute and chronic ITP. Higher proportion of chronic ITP patients (5/9; 55.5%) than acute ITP patients (7/51; 13%) had symptom duration longer than 1 month (P <0.05). Increased initial reticulated platelet percentage (more than 8%) was noted in 55.3% (21/38) of acute ITP and in 40% (2/5) of chronic ITP. There were no significant differences in initial platelet count, lowest platelet count, antiplatelet IgM, antiplatelet IgG, ANA and Coombs' test between two groups. The response to initial treatment were excellent in acute and chronic ITP. Six cases of acute ITP relapsed within 1 month from initial presentation. Eight cases of chronic ITP relapsed, among them 5 cases relapsed after 2 months from initial presentation.
CONCLUSION
We suggest that patients with > or =1 months duration of presenting symptoms and relapse after 2 months from initial presentation have the propensity of developing chronic ITP. Reticulated platelet percentage could not discriminate acute and chronic ITP. A more accurate detection method should be developed for reticulated platelets.