EDTA-dependent pseudothrombocytopenia mimicking dengue-associated severe thrombocytopenia: a case report.

INTRODUCTION

We report a case of suspected dengue fever that was ultimately diagnosed as ethylenediaminetetraacetic acid (EDTA)-dependent pseudothrombocytopenia in a 24-year-old man presenting with frontal headache, malaise, and recent fever.

CASE PRESENTATION: A previously healthy 24-year-old man presented with thrombocytopenia, with an initial platelet count of 25 × 109/L. He reported a 1-week history of frontal headache, severe dizziness, generalized weakness, and recent fever. There was no history of bleeding or bruising. Given the degree of thrombocytopenia and a regional increase in dengue cases, dengue fever was the provisional diagnosis. The patient was admitted for further evaluation and conservative management. A peripheral blood smear revealed morphologically normal platelets with marked clumping, raising suspicion of EDTA-dependent pseudothrombocytopenia. Paired blood samples were drawn in EDTA and sodium citrate tubes. The EDTA sample showed a platelet count of 42 × 109/L, whereas the citrate sample showed a count of 191 × 109/L, confirming the diagnosis. The patient remained clinically stable and was discharged. After discharge dengue serology returned back negative.

CLINICAL DISCUSSION: In patients presenting with thrombocytopenia, the clinical picture is essential in guiding appropriate management. While it is important to maintain a low threshold for suspecting dengue fever, clinicians should also broaden the differential diagnosis to include pseudothrombocytopenia.

CONCLUSION

This case report serves as a learning example that physicians should remain vigilant for EDTA-dependent pseudothrombocytopenia and request peripheral smears and citrate-based counts in cases of unexplained thrombocytopenia. Awareness of laboratory limitations in addition to correlation with clinical picture is a must for clinicians.