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Thrombocytosis

Issue Description
Thrombocytosis is defined as increased number of circulating platelets.


Causes
Proposed causes of thrombocytosis include anemia, iron deficiency, inflammatory cytokines, and paraneoplastic production of thrombopoietin. Anemia and thrombocytopenia can be seen in dogs with primary and metastatic hepatic hemangiosarcoma(HSA). Prolonged coagulation times and clotting factor abnormalities have been identified in dogs with hepatobiliary tumors, although these are rarely clinically relevant.

Symptoms
High platelet levels do not necessarily signal any clinical problems, and are picked up on a routine full blood count. However, it is important that a full medical history be elicited to ensure that the increased platelet count is not due to a secondary process. Often, it occurs in tandem with an inflammatory disease, as the principal stimulants of platelet production (e.g. thrombopoietin) are elevated in these clinical states as part of the acute phase reaction.

High platelet counts can occur in patients with polycythemia vera (high red blood cell counts), and is an additional risk factor for complications.

The highest platelet counts usually produce the most severe symptoms.


Diagnosis
Laboratory tests might include: full blood count, liver enzymes, renal function and erythrocyte sedimentation rate. If the cause for the high platelet count remains unclear, bone marrow biopsy is often undertaken, to differentiate whether the high platelet count is reactive or essential.

Treatment
Treatment for thrombocytosis depends on the underlying condition that causes it. In most cases, the platelet count will return to normal after the condition is resolved.

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