Primary Thrombocytosis in Babies

I would like to introduce my graduate project “Thrombocytosis in babies” by giving a definition of thrombocytosis and explaining primary thrombocytosis. And then, in later posts I will be focusing more on causes, clinical presentation, pathophysiology, and diagnosis of thrombocytosis in children and babies.

Thrombocytosis in babies

Platelet counts physiologic reference range is 150-400 X 10⁹/L. Thrombocytosis is when platelet count exceed the upper limit. It can be primary or secondary.

 

This is a blood smear of a patient with thrombocytosis: 

                            http://www.thailabonline.com/blood/thrombocytosis1.jpg

Primary thrombocytosis:

There are 2 types of primary thrombocytosis or essential thrombocytosis. Classical primary thrombocytosis is the first type. It is caused by continuous production of platelets, which in this case is not regulated by the physiologic negative feedback mechanism that usually maintains platelet count within the reference range. It can be due to a myeloproliferative disorder such as polycythemia vera, essential thrombocythemia, chronic myelocytic, myelofibrosis with myeloid metaplasia or, very rarely, it can be due to an acute myelocytic leukemia. These patients represent a monoclonal hematopoiesis. Endogenous erythroid colony growth is the main characteristic of their hematopoiesis, with an increase in the expression of granulocyte polycythemia rubra vera-1 (PRV-1) RNA, and is associated by JAK2^V617Fmutation in nearly 30% of the pediatric cases.

However, the second type of primary thrombocytosis is classified as familial thrombocytosis and is due to a mutation of either thrombopoietin receptor gene (mpl) or thrombopoietin (TPO) gene.  Hematopoiesis in familial thrombocytosis is polyclonal.