title: Thrombocytosis. Etiologic analysis of 663 patients.
abstract: Six hundred sixty-three children aged 1 to 16 years with thrombocytosis (defined as a platelet count of more than 500 x 10(9)/L) seen in a university hospital over a 1-year period were studied prospectively for etiology. The causes of thrombocytosis were infection (30.6%), hemolytic anemia (19.3%), tissue damage (15.2%), rebound thrombocytosis (14.8%), chronic inflammation (4.1%), renal disorders (4.1%), and malignancy (2%). Thrombocytosis associated with multiple, simultaneous causative factors was seen in 3.3% of cases. Among all patients with infections, osteomyelitis and septic arthritis were associated with higher platelet counts than other infections (P < .0001). Thrombocytosis secondary to infections was significantly more common in children under 5 years of age, whereas chronic inflammation, malignancy, and renal disorders were more common causes of thrombocytosis in children over 5 years of age. Thrombocytosis of 1 million or more platelets was seen in 13 (2%) children. No thrombocytosis-related complications were seen in any children, and none required any specific treatment. Thrombocytosis is a frequent finding in children. It is due to a variety of etiologic factors and is of little clinical discriminatory value. It is often due to an acute-phase phenomenon in response to infection, tissue damage, blood loss, or anemia, and is rarely due to malignancy.
authors.affiliation: Department of Pediatrics, King Khalid University Hospital, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: M D
authors.initials: MD
authors.lastname: Yohannan
authors.forename: K E
authors.initials: KE
authors.lastname: Higgy
authors.forename: S A
authors.initials: SA
authors.lastname: al-Mashhadani
authors.forename: C R
authors.initials: CR
authors.lastname: Santhosh-Kumar
mesh_terms: D000210:Acute-Phase Reaction; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D011446:Prospective Studies; D013922:Thrombocytosis / Q000209:etiology*