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Extreme thrombocytosis predicts Kawasaki disease in infants
Lise E Nigrovic1, Peter A Nigrovic, Marvin B Harper
1Division of Emergency Medicine, Children's Hospital Boston, Boston, MA 02115, USA.
Insights
Kawasaki disease in infants can be life-threatening. High platelet counts in febrile infants may indicate Kawasaki disease, aiding early diagnosis when classic symptoms are absent.
Area of Science:
- Pediatrics
- Immunology
- Cardiology
Background:
- Kawasaki disease (KD) poses a significant risk for coronary artery complications in infants.
- Infants often present with atypical symptoms, delaying diagnosis.
- Timely diagnosis is crucial to prevent severe cardiac sequelae.
Purpose of the Study:
- To investigate the association between platelet count and Kawasaki disease in febrile infants.
- To identify potential diagnostic markers for Kawasaki disease in infants presenting without full classic features.
Main Methods:
- Retrospective analysis of 26,540 infants (≤1 year) evaluated in a pediatric emergency department.
- Examination of platelet counts in infants with fever of unknown origin.
- Statistical analysis, including likelihood ratios, to assess the diagnostic value of high platelet counts.
Main Results:
- 8.5% of febrile infants with platelet counts ≥800,000 cells/mm³ had Kawasaki disease.
- Only 0.4% of febrile infants with platelet counts <800,000 cells/mm³ had Kawasaki disease.
- A platelet count ≥800,000 cells/mm³ yielded a likelihood ratio of 17 for Kawasaki disease.
Conclusions:
- Elevated platelet counts are a significant indicator of Kawasaki disease in febrile infants.
- Consider Kawasaki disease in infants ≤1 year with prolonged fever and extremely high platelet counts, especially when other diagnoses are unclear.
- High platelet count can aid in the early diagnosis of Kawasaki disease in atypical presentations.
Abstract:
Infants with Kawasaki disease are at high risk of developing life-threatening coronary complications, yet may elude timely diagnosis because they often lack the full complement of classic clinical features. We retrospectively studied 26,540 children 1 year of age or less who were evaluated at a tertiary care pediatric emergency department in whom a platelet count was performed. Among those infants with fever without a source identified, 8.5% with platelet counts of 800,000 cells/mm(3) or greater had Kawasaki disease compared to 0.4% with platelet counts of less than 800,000 cells/mm(3) (likelihood ratio for Kawasaki disease was 17 [95% confidence interval, 8-34]). Because many infants present atypically, Kawasaki disease should be considered in all children of 1 year or less with prolonged fever, extreme elevation of the platelet count, and no compelling alternative diagnosis.