Pediatric Thrombocytosis Treatment & Management

Updated: Aug 17, 2020
  • Author: Susumu Inoue, MD; Chief Editor: Hassan M Yaish, MD  more...
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Medical Care

Normally, no treatment is necessary for reactive thrombocytosis. Rarely, in patients who have reactive thrombocytosis and a known risk factor for thrombosis, such as factor V Leiden mutation, the thrombotic risk may be increased. However, no information is currently available regarding the magnitude of the risk. Therefore, one should consider each case individually for prophylaxis of thrombosis.

In vasculitis syndrome with thrombocytosis (in particular, in Kawasaki syndrome), treatment with aspirin is recommended (see Kawasaki Disease). In primary thrombocytosis, prophylactic use of antithrombotic agents has not been well delineated. In general, platelet-lowering agents have been recommended for high-risk adult patients, ie, those with an increased cardiovascular risk or a previous history of thrombosis or who are older than 60 years (see Medication). Indications for thrombosis prophylaxis are not firmly established for children; the use of antithrombotics and anticoagulants should be individualized, weighing the risks and benefits.

In adult patients with posttrauma thrombocytosis (platelet count >1 million), treatment with aspirin showed no effect in the rate of mortality, complications, and length of ICU stay. However, these results are from a retrospective, nonrandomized study; thus, they do not answer whether aspirin is useful in this group of patients. Anticoagulation to prevent thrombosis with heparin or low–molecular-weight heparin is the standard of care for these adult patients, unless there are bleeding problems.

In patients in whom primary thrombocytosis is strongly suspected, laboratory studies mentioned in the previous section and evaluation of family members are needed to confirm the diagnosis. Morphologic and cytogenetic examination of bone-marrow cells and marrow reticulin stains should be repeated in patients with a changing hematologic picture (refer patients to a hematologist).

Evolution of primary thrombocytosis to frank acute myeloblastic leukemia (AML), myelofibrosis/agnogenic myeloid metaplasia (AMM), or myelodysplastic syndrome (MDS) has been documented in adults and represents a progression of disease. The prognosis after this progression is poor. However, successful allogeneic bone-marrow or stem-cell transplantation has been reported in patients who developed AML/MDS and/or myelofibrosis. Therefore, keep this modality in mind when treating primary thrombocytosis. More detailed discussion of pediatric primary thrombocytosis is found in an article by Kucine et al. [1]



A persistent increase in neutrophil counts with immature forms (eg, metamyelocytes, myelocytes), persistent increase in basophils and eosinophils, and splenomegaly suggest a chronic myelocytic leukemia (CML). Kastan et al described two children whose clinical findings and blood counts best fit essential thrombocytosis (ET) but whose bone-marrow cytogenetic analyses showed the presence of the Philadelphia (Ph1) chromosome. Both of these patients presented with platelet counts in excess of 2 million/μL. [50] Another child with CML presented with the initial platelet count of 2.8 million/μL. [5]

A persistent increase in the hematocrit (with or without a change in the WBC count) with thrombocytosis suggests polycythemia vera. The image below shows suggested workup algorithm for thrombocytosis.

Algorithm for thrombocytosis workup and potential Algorithm for thrombocytosis workup and potential need for medication.

One should consult a hematologist if a workup for ET is needed. Older children with thrombocytosis with thrombosis (suspected or demonstrated) or a history of thrombosis, increased bleeding tendency despite thrombocytosis, or splenomegaly must promptly be referred to a hematologist. Also, a family history of thrombocytosis requires consultation with a hematologist and geneticist because a genetic work-up is necessary.



No medical reason warrants the limitation or encouragement of activity in a child with thrombocytosis. A child with a substantially enlarged spleen (usually caused by essential or familial thrombocythemia) requires necessary precautions regarding their activity to prevent splenic rupture.