thrombocytosis (thrombocythemia)
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Etiology
- myeloproliferative disorders
- secondary thrombocytosis
- recovery from acute infection
- malignancy
- hemolytic anemia
- postoperative
- acute & chronic hemorrhage
- iron deficiency
- pharmaceutical agents
- chronic inflammatory disorders
- exercise
- stress
- recovery from myelosuppressive therapy
- therapy of vitamin B12 deficiency
- osteoporosis
Epidemiology
- secondary thrombocytosis is more common than essential thrombocythemia
- 20% of patients with essential thrombocythemia are < 40 years of age[2]
Genetics
- associated with JAK2 V617F mutation
- autosomal dominant form associated with defects in THPO
Clinical manifestations
- essential thrombocytosis is associated with
- 2/3 of patients with essential thrombocytosis are asymptomatic
- secondary thrombocytosis is NOT associated with thrombosis, hemorrhage, splenomegaly
Laboratory
- complete blood count (CBC) sufficient if secondary thrombocytosis
- elevated platelet count (> 600,000/uL)
- platelet count can exceed 1E06/uL for primary or secondary thrombocytosis
- normal red cell volume (MCV)
- hemoglobin < 13 g/dL
- leukocyte count elevated in 1/2 of patients with essential thrombocythemia
- basophilia may be noted[2]
- impaired platelet aggregation response to:
- comprehensive metabolic panel
- hyperkalemia if platelets > 1E06/mm3
- lysis of platelets or leukocytes during clot formation & retraction
- determine plasma K+ rather than serum K+
- hyperkalemia if platelets > 1E06/mm3
- bone marrow biopsy
- presence of adequate iron
- absence of collagen fibrosis
- absence of Philadelphia chromosome or other bcl-abl gene rearrangements
- stem cell culture
- spontaneous growth of megakaryocyte colony forming units in essential thrombocythemia
- JAK2 V617F mutation (essential thrombocythemia)
- calreticulin gene mutation
- MPL gene mutation
Complications
- essential thrombocythemia associated with arterial thrombosis venous thrombosis, hemorrhage, splenomegaly
- secondary thrombocytosis is NOT associated with thrombosis, hemorrhage, splenomegaly, or abnormal cytogenetic findings
Management
- see essential thrombocythemia
- hydroxyurea for high-risk essential thrombocythemia
- secondary thrombocytosis: treat underlying disorder
More general terms
More specific terms
Additional terms
References
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1763
- ↑ 2.0 2.1 2.2 Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 16, 17, 19. American College of Physicians, Philadelphia 1998, 2006, 2012, 2015, 2022
Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025 - ↑ 3.0 3.1 Schiller G, in: UCLA Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001
- ↑ Geriatrics at your Fingertips, 13th edition, 2011 Reuben DB et al (eds) American Geriatric Society
- ↑ Sulai NH, Tefferi A. Why does my patient have thrombocytosis? Hematol Oncol Clin North Am. 2012;26:285-301, viii. PMID: https://pubmed.ncbi.nlm.nih.gov/22463828