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:
- hyperkalemia if platelets > 1E06/mm3
- lysis of platelets or leukocytes during clot formation & retraction
- determine plasma K+ rather than serum K+
- 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)
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
- ↑ 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