Dear Sir,

We read the article ’Isolated thrombocytopenia in childhood: what if it is not immune thrombocytopenia?’ with great interest.(1) Lee presented case studies on interesting situations that might be misinterpreted as immune thrombocytopenia.(1) In fact, several pathologies can result in isolated thrombocytopenia in childhood. Although it is not common, non-immune thrombocytopenia is possible.

We agree with Lee’s conclusion that “secondary thrombocytopenia is not an uncommon diagnosis among children presenting with isolated thrombocytopenia and should be looked out for at the initial diagnosis and during the subsequent follow-up until thrombocytopenia resolves.”(1) However, we would like to note another forgotten possibility that might result in a missed diagnosis of isolated thrombocytopenia. In laboratory medicine, a pre-analytical error may be an important cause of abnormal blood smear interpretation. With poor blood collection and mixing of specimen, the pseudopathology of anticoagulant-associated pseudothrombocytopenia might occur. Hence, before any further investigation, it is necessary to recheck the quality of the haematology laboratory process. Magnesium-anticoagulated blood samples should be used for confirmation, to rule out the problem of in vitro aggregation of platelets in the presence of ethylenediaminetetraacetic acid as an anticoagulant.(2)

Yours sincerely,

Lee AC. Isolated thrombocytopenia in childhood: what if it is not immune thrombocytopenia?. Singapore Med J. 2018;59:390-3.
Kohlschein P, Bänsch D, Dreißiger K, Schuff-Werner P. Exclusion of thrombocytopenia as a contraindication for invasive radiofrequency ablation in a patient with paroxysmal atrial fibrillation by using magnesium anticoagulation instead of EDTA: another case of anticoagulant-induced pseudo-thrombocytopenia. Heart Surg Forum. 2015;18:E090-2.