Objective: To identify the haematological causes of thrombocytopenia in children admitted at a tertiary care hospital.

Methods: The prospective, descriptive study was carried out at the Aga Khan University Hospital, Karachi, from September 3, 2009 to March 3, 2010, and comprised children between one month and 14 years of age with platelet count less than15000. After reviewing the record, a questionnaire was filled and data was analysed using SPSS 15.

Results: Out of 108 patients in the study, 69 (64%) were male and 39 (36%) were female. The overall mean age was 69±46.54 months (range: 12-168 months). The mean platelet count was 59.8±46.1/l (range: 1,000-149,000/l). Besides, 24 (22.2%) children had mild thrombocytopenia, 34 (31.5%) had moderate and 50 (46.3%) had severe thrombocytopenia. The causes of haematological thrombocytopenia in descending order of frequency was acute lymphoblastic leukaemia 17 (15.7%), idiopathic thrombocytopenic purpura 10 (8.3%) and aplastic anaemia 5 (4.6%).

Conclusion: Acute lymphoblastic leukaemia was the commonest cause of haematological thrombocytopenia followed by idiopathic thrombocytopenic purpura and aplastic anaemia.