Introduction: Red cell fragmentation may result in erroneously high platelet counts by automated blood counters. Therefore, any abnormal platelet counts in a full blood count analysis should be re-evaluated either using blood film manual counting or with more accurate automated analysis options. Case Report: We report a case of Haemoglobin-H disease that was noted to have a very high platelet count, by newly installed automated blood analyser, during regular follow up. Manual platelet counts and the automated analysis using flowcytometric counting of the same analyser showed a normal platelet count. Conclusion: A wide spectrum of blood disorders can cause pseudothrombocytosis. Whenever an unexpected high platelet count is encountered, alternative modalities should be used to confirm the actual platelet count such as manual count on a blood film. Furthermore, machines using the impedance principle need to be calibrated to reduce the chances of getting abnormal results with actual normal platelet counts.

Pseudothrombocytosis, Red cell fragmentation, Hb-H disease