Clinicohematological study of thrombocytosis

To find out etiology and clinical course of thrombocytosis in Indian pediatric population.

A total of 250 patients having thrombocytosis (defined as platelet count >500 x 10(9)/L) on haematological investigations were studied over one yr period. All patients were evaluated clinically and were subjected to investigations, including complete blood counts (CBC) with peripheral smear examination. To elucidate the possible role of inflammatory cytokines in pathogenesis of RT, levels of Interleukin-6 (IL-6) and C - reactive protein (CRP) were estimated.

Infants and young children (<2 yr age) were most common group, contributing 60% of total cases. Out of total 250 cases, only 3 (1.2%) cases were found to have primary thrombocytosis and remaining 98.8% cases were having RT. Among RT patients, infections (alone or in association with iron deficiency anemia) were most common cause, accounting for 65% cases, while iron deficiency anemia (IDA) was second most common cause accounting for 41.3% cases (12.6% IDA alone and 28.7 % in association with infections). Other causes included nutritional dimorphic anemia and patients on treatment for megaloblastic anemia, acute lymphoblastic leukemia (during treatment) and lymphoma. Among various groups of RT, IL-6 and CRP levels were higher in patients with infection with or without IDA than IDA alone. One child with essential thrombocytosis and one child with RT had thrombotic complications. On follow up, platelet counts normalized in most of the patients with treatment of underlying conditions.

Results of this study suggest that essential thrombocytosis is extremely rare in children. Infections and IDA (alone or in association with infections) are common causes of RT. IL-6 and CRP levels are increased in patients with RT, to a higher level in patients with infections than in patients with IDA. Most patients with RT have uneventful recovery of platelet counts to normal range with treatment for underlying condition.