Rate of Rise of Platelet Count After IVIG for Pediatric Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease causing platelet destruction, and is a common cause of symptomatic thrombocytopenia in children. Intravenous immune globulin (IVIG) is a treatment for ITP that increases the platelet counts of most patients within 24 to 48 hours. This study aimed to calculate the rate of rise in pediatric ITP after a dose of IVIG and to analyze if patient characteristics affected the rate. For 116 children treated for ITP with IVIG at Hershey Medical Center, the rate of rise of the platelet count for all patients was calculated. The rate of rise ranged from -0.1 to +4.2 K/µL/hour (average 1.3, median 1.2). 78% of patients had a rate of rise of over 0.5 K/µL/hour. There was a statistically significant correlation between the rate rise of the platelet count and the initial platelet count (P=0.0197), but rate was not affected by age or sex. This study was able to demonstrate that IVIG is effective in most patients and that demographic features do not affect the rate of rise. By providing a nomogram showing when to expect a meaningful rise in the platelet count after IVIG, we give guidance for timing of the postinfusion platelet count to avoid administering a second dose. Future studies are needed to test this nomogram prospectively.