Long term changes in platelet counts after H. pylori eradication in non-ITP patients.

Helicobacter pylori eradication is becoming a first-line therapy against idiopathic thrombocytopenic purpura (ITP) and its long term efficacy has already been reported. In contrast, eradication therapy reduced peripheral platelets in non-ITP patients 8 weeks later. To confirm the long term efficacy of Helicobacter eradication on platelet counts in non-ITP patients, we evaluated changes in peripheral platelet counts in endoscopically diagnosed patients with Helicobacter infection. Endoscopically diagnosed patients with Helicobacter infection received eradication therapy using amoxicillin (1500 mg/day), clarithromycin (400 mg/day) and lansoprazole (60 mg/day). The changes in platelet counts after Helicobacter eradication were serially evaluated for as long as 3 years or more. In total, 294 patients were enrolled: 243 patients successfully received eradication therapy and 51 were unsuccessfully treated. As a whole, peripheral platelet counts significantly decreased after Helicobacter eradication, being reduced by more than 1.0 × 10⁹/l by 5-6 months, 1 year, 2 years and 3 years or more (from 24.2+/-5.6 to 23.1+/-5.0, 23.0+/-5.0, 22.1+/-4.5, 22.4+/-5.6, and 21.6+/-5.3 × 10⁹/l: p = <0.0001, <0.0001, 0.0001, 0.0052, and <0.0001, respectively). Helicobacter pylori eradication finally reduced peripheral platelet counts around 2.0 × 10⁹/l in non-ITP patients. There was a definite difference in platelet regulation by Helicobacter pylori between ITP and non-ITP patients. These bivalent effects, upregulation and downregulation, on the peripheral platelet induced by Helicibacter pylori infection appeared to originate from quite different mechanisms.