In the Nordic countries, ITP mainly affects children aged 0-7 y, with a winter bulk of postinfectious cases superimposed on a steady occurrence of non-infectious cases. Clinically, it may be useful to distinguish between children with sudden versus insidious onset of symptoms rather than between different age groups.

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Aim: To describe the epidemiology of idiopathic thrombocytopenic purpura (ITP) in the Nordic countries, to define clinical subgroups and to investigate factors predicting chronic disease. Methods: A prospective registration was done from 1998 to 2000, including all children with newly diagnosed ITP aged 0–14 y and at least one platelet count <30×109/l. Results: 506 children were registered and 423 followed for 6 mo. The incidence was 4.8/105 per year. Most children were aged 0–7 y (78%), with a predominance of boys, while patients aged 8–14 y had equal representation of the two sexes. There were seasonal variations determined by variations in postinfectious cases with sudden onset. The platelet count was <10×109/l in 58%, but bleeding manifestations were mild or moderate in 97%. The insidious form (symptoms for more than 2 wk) was more frequent in older children and girls, showed little seasonal variation, had milder manifestations and ran a chronic course in more than half the cases. Intracranial haemorrhages did not occur in the first 6 mo after diagnosis. Chronic ITP developed in 25%. The strongest predictor of chronic disease was insidious onset of symptoms (OR 5.97). Conclusion: In the Nordic countries, ITP mainly affects children aged 0–7 y, with a winter bulk of postinfectious cases superimposed on a steady occurrence of non‐infectious cases. Clinically, it may be useful to distinguish between children with sudden versus insidious onset of symptoms rather than between different age groups.

Treatment with pulsed high-dose dexamethasone is not always effective in children with chronic ITP, but it is worth trying in severe symptomatic chronic childhood ITP.

The diagnosis of type 1 von Willebrand disease (VWD), the most common inherited bleeding disorder in humans, is greatly dependent on an accurate diagnosis of significant mucocutaneous bleeding. In a previous study, the authors modified the criteria of the International Society on Thrombosis and Haemostasis for significant mucocutaneous bleeding to a format, the Hospital for Sick Children (HSC) criteria, that was more applicable to diagnose significant mucocutaneous bleeding in children. To assess the reliability and reproducibility of classification of subjects as "bleeders" versus "non-bleeders" using a questionnaire for significant mucocutaneous bleeding targeted to children, 39 subjects interviewed for a previous HSC VWD study were reinterviewed for the current study. The original bleeding classification was confirmed in 80% of subjects interviewed for a second time, indicating that this method of classification is reproducible (kappa = 0.65), with a "substantial" agreement among the investigators who reviewed the questionnaire responses (kappa = 0.71). The validity and utility of the HSC questionnaire for primary screening of children with suspected mucocutaneous bleeding disorders merits assessment in further clinical studies.

Overall T cell expansion frequency was the same as in healthy individuals. However, the presence of expansions that normalized with treatment suggests the presence of specific T cells implicated in the pathogenesis of ITP.

Hedlund-Treutiger I, Wahlström J, Elinder G. Role of the T cell receptor in idiopathic thrombocytopenic purpura (ITP). Acta Paediatr 1998; Suppl 424: 46-50. Stockholm. ISSN 0803-5253.During the past few decades a number of studies has described T cell defects and attempted to elucidate their role in the pathogenesis of idiopathic thrombocytopenic purpura (ITP). Some studies implicate T cells as potential initiators of autoantibody production in ITP. However, only a few of these have studied the role that the T cell receptor may play in the pathogenesis of ITP. In a variety of autoimmune syndromes interest has focused on the aand b-chains of the T cell receptor. Deviations from the normal T cell receptor gene usage have been reported in rheumatoid arthritis, systemic lupus erythaematosus and multiple sclerosis. Usually, these studies have shown a restricted heterogeneity of T cell receptor variable gene usage. The studies on the T cell receptor in ITP have included a limited number of patients, which makes it difficult to evaluate the significance of the role that the T cell receptor may play in the pathogenesis of ITP. Further studies are warranted. ٖ Idiopathic thrombocytopenic purpura, T cell clones, T cell receptor

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