Essential Thrombocytosis Workup
- Author: Asheesh Lal, MBBS, MD; Chief Editor: Emmanuel C Besa, MD more...
Tests and procedures used in the workup for essential thrombocytosis include the following:
Complete blood cell count (CBC)
Genetic studies – For JAK2 V617F, CALR, and MPL mutations
Bone marrow aspirate and biopsy
Platelet aggregation studies
Cytogenetic study results are usually normal. Molecular studies (eg, polymerase chain reaction [PCR], Southern [genomic] blotting) may be used as sensitive means of excluding chronic myelogenous leukemia.
Computed tomography (CT) scanning or ultrasonography of the spleen may reveal splenomegaly in patients with essential thrombocytosis even when this condition is not physically detectable.
Approximately 90% of patients with essential thrombocytosis show an increase in bone marrow cellularity. Megakaryocytic hyperplasia is present. Giant megakaryocytes are frequently observed, and clusters of megakaryocytes may be present. Significant dysplasia of the megakaryocytes is unusual. Hyperplasia of granulocyte and reticulocyte precursors is common. Bone marrow reticulin is usually increased, but collagen fibrosis is uncommon.
In essential thrombocytosis, as in other myeloproliferative disorders, bone marrow iron stain results may be negative when other studies do not support the presence of iron deficiency. For practical purposes, a ferritin level that is within the reference range or increased, along with an RBC mean corpuscular volume (MCV) that is within the reference range, is sufficient to exclude reactive thrombocytosis secondary to iron deficiency and the possibility of polycythemia vera masked by iron deficiency.
A complete blood cell count (CBC) is essential for the diagnosis of essential thrombocytosis. CBC findings are as follows:
The hallmark of essential thrombocytosis (primary thrombocythemia) is a sustained, unexplained elevation in the platelet count
Leukocytosis, erythrocytosis, and mild anemia may also be found
The peripheral blood may show occasional immature precursor cells (eg, myelocytes, metamyelocytes); large platelets (thrombocytes) are typically identifiable on routine peripheral blood smear
Mild basophilia and eosinophilia may be found
The results of the prothrombin time (PT) and activated partial thromboplastin time (aPTT) studies are usually within reference ranges. The bleeding time may or may not be prolonged.
Platelet aggregation study findings are abnormal and show impaired platelet aggregation to epinephrine, adenosine diphosphate, and collagen but not to ristocetin and arachidonic acid. Some patients may present with spontaneous platelet aggregation.
A red blood cell (RBC) mass study helps to exclude polycythemia vera. The RBC mass is elevated in polycythemia vera, but is normal in essential thrombocytosis.
Other blood work results are as follows:
Uric acid (UA) levels are elevated in 25% of patients at diagnosis
Pseudohyperkalemia may occur, and falsely elevated phosphorus (P) and acid phosphatase levels may be noted
Pseudohypoxemia may develop from extreme thrombocytosis
Vitamin B-12 levels are increased in 25% of patients
Elevation of C-reactive protein (CRP), fibrinogen, and interleukin 6 levels suggests secondary thrombocytosis, because those are acute-phase reactants
On in vitro studies using peripheral blood mononuclear cells, an increase in the formation of endogenous erythroid cells and/or megakaryocytic colonies with increased sensitivity to interleukin-3 indicates the presence of abnormal hematopoietic progenitor cells. This finding is a diagnostic criterion for essential thrombocytosis; however, the test is primarily a research tool.
The principal mutations found in patients with essential thrombocytosis are in the JAK2 and CALR genes. Mutations in the MPL gene have been found in up to 4% of patients with essential thrombocytosis, but the prognostic significance of its presence is unclear.
The JAK2 V617F mutation is present in 50% of patients with essential thrombocytosis. V617F -positive patients displayed multiple features resembling polycythemia vera, with significantly higher hemoglobin levels, neutrophil counts, bone marrow erythropoiesis and granulopoiesis, more venous thromboses and a higher incidence of polycythemic transformation.
Teofili et al noted that specific JAK2 mutations activate the JAK-STAT pathway in polycythemia vera and essential thrombocytosis, with the presence of biologic markers such as endogenous erythroid colony (EECs) growth or over expression of polycythemia rubra vera 1 gene (PRV-1), RNA. Because these findings are also seen in patients with wild-type JAK2, the authors hypothesized that a deregulation of the suppressor of cytokine signaling (SOCS) protein system in these cases could produce the activation of the JAK-STAT pathway.
Teofili et al evaluated 81 patients with polycythemia vera and essential thrombocytosis (53 adults and 28 children) for the methylation status of the SOCS-1, SOCS-2 and SOCS-3 CpG islands and for several myeloproliferative markers (including JAK2 and MPL mutations and clonality of hematopoiesis). The authors identified SOCS-1 or SOCS-3 hypermethylation in 23 patients, which was associated with a significant decrease of SOCS-1 or SOCS-3 RNA and protein levels, and demonstrated that the gene expression was restored by exposing cells to the demethylating agent 2-deoxyazacytidin. The investigators concluded that "SOCS-1 or SOCS-3 hypermethylation can activate the JAK-STAT signaling pathway in alternative or together with JAK2 mutations," which may "represent a potential therapeutic target."
Ohyashiki et al studied JAK2 mutational status with cytogenetic analysis in 54 patients with essential thrombocythemia to obtain evaluate the correlation between clinicohematologic features and genetic abnormalities.[24, 25] These investigators found that recurrent der(9;18) in essential thrombocythemia with JAK2 V617F is highly linked to myelofibrosis development.
Ohyashiki et al reported that of six patients with essential thrombocytosis who developed myelofibrosis, four had JAK2 V617F mutation. In addition, three of four patients with JAK2 V617F had add(18)(p11). However, the remaining two patients with essential thrombocytosis who developed myelofibrosis did not have JAK2 V617F or add(18)(p11), and none of the patients with essential thrombocytosis and JAK2 V617F and chromosome changes other than add(18)(p11) developed myelofibrosis. The authors concluded that "add(18)(p11), possibly due to der(9;18), may contribute a link to myelofibrosis in" JAK2 V617F -positivity in patients with essential thrombosis, whereas "those with wild-type JAK2 may use another pathway toward myelofibrosis."
Mutations in the calreticulin (CALR) gene have been reported in 15-25% of patients with essential thrombocytosis. CALR mutations have been found to be exclusive of JAK-2 and MPL mutations. Initial studies have indicated that patients with CALR mutations are younger; more frequently male; and have higher platelet counts, lower hemoglobin and leukocyte counts, and a lower risk of thrombosis than those with the JAK2 mutation. There has been no difference in the rate of transformation to myelofibrosis.
Bone Marrow Aspirate and Biopsy
A bone marrow aspirate and biopsy are useful. Use specialized needles to obtain the aspirate and biopsy material over the posterior iliac crest. Obtaining an aspirate over the sternum may also be helpful, although most physicians prefer the posterior iliac crest. Do not attempt to obtain a biopsy from the sternum.
Bone marrow findings in essential thrombocytosis are as follows:
Approximately 90% of patients with show an increase in bone marrow cellularity
Megakaryocytic hyperplasia is common
Giant megakaryocytes are often observed; clusters of megakaryocytes may be present; significant dysplasia of the megakaryocytes is unusual
Hyperplasia of granulocyte and reticulocyte precursors is common
Bone marrow reticulin is usually increased,  but collagen fibrosis is uncommon
Iron stores may be absent in the bone marrow; this may be due to gastrointestinal tract bleeding or menorrhagia. However, in essential thrombocytosis, as in other myeloproliferative disorders, bone marrow iron stain results may be negative even when other studies do not support the presence of iron deficiency
Epstein E, Goedel A. Hammorhagische thrombocythamie bei vascularer schrumpfmilz. Virch Arch (Pathol Anat). 1934. 292:233.
Harrison CN, Gale RE, Machin SJ, Linch DC. A large proportion of patients with a diagnosis of essential thrombocythemia do not have a clonal disorder and may be at lower risk of thrombotic complications. Blood. 1999 Jan 15. 93(2):417-24. [Medline]. [Full Text].
Barbui T, Finazzi G. Treatment indications and choice of a platelet-lowering agent in essential thrombocythemia. Curr Hematol Rep. 2003 May. 2(3):248-56. [Medline].
Ruggeri M, Gisslinger H, Tosetto A, et al. Factor V Leiden mutation carriership and venous thromboembolism in polycythemia vera and essential thrombocythemia. Am J Hematol. 2002 Sep. 71(1):1-6. [Medline]. [Full Text].
Harrison CN, Donohoe S, Carr P, et al. Patients with essential thrombocythaemia have an increased prevalence of antiphospholipid antibodies which may be associated with thrombosis. Thromb Haemost. 2002 May. 87(5):802-7. [Medline].
Bucalossi A, Marotta G, Bigazzi C, Galieni P, Dispensa E. Reduction of antithrombin III, protein C, and protein S levels and activated protein C resistance in polycythemia vera and essential thrombocythemia patients with thrombosis. Am J Hematol. 1996 May. 52(1):14-20. [Medline].
Colombi M, Radaelli F, Zocchi L, Maiolo AT. Thrombotic and hemorrhagic complications in essential thrombocythemia. A retrospective study of 103 patients. Cancer. 1991 Jun 1. 67(11):2926-30. [Medline].
Fenaux P, Simon M, Caulier MT, et al. Clinical course of essential thrombocythemia in 147 cases. Cancer. 1990 Aug 1. 66(3):549-56. [Medline].
Chistolini A, Mazzucconi MG, Ferrari A, et al. Essential thrombocythemia: a retrospective study on the clinical course of 100 patients. Haematologica. 1990 Nov-Dec. 75(6):537-40. [Medline].
Hehlmann R, Jahn M, Baumann B, Köpcke W. Essential thrombocythemia. Clinical characteristics and course of 61 cases. Cancer. 1988 Jun 15. 61(12):2487-96. [Medline].
Bellucci S, Janvier M, Tobelem G, et al. Essential thrombocythemias. Clinical evolutionary and biological data. Cancer. 1986 Dec 1. 58(11):2440-7. [Medline].
Kwon M, Osorio S, Muñoz C, Sánchez JM, Buno I, Díez-Martín JL. Essential thrombocythemia in patients with platelet counts below 600x10(9)/L: applicability of the 2008 World Health Organization diagnostic criteria revision proposal. Am J Hematol. 2009 Jul. 84(7):452-4. [Medline].
Cervantes F. Management of essential thrombocythemia. Hematology Am Soc Hematol Educ Program. 2011. 2011:215-21. [Medline].
Lee HS, Park LC, Lee EM, Lee SJ, Shin SH, Im H, et al. Incidence Rates and Risk Factors for Vascular Events in Patients With Essential Thrombocythemia: A Multicenter Study From Korea. Clin Lymphoma Myeloma Leuk. 2011 Nov 14. [Medline].
Genetics Home Reference. Essential Thrombocythemia. U.S. National Library of Medicine. Available at http://ghr.nlm.nih.gov/condition/essential-thrombocythemia. November 2, 2015; Accessed: November 5, 2015.
Rumi E, Pietra D, Ferretti V, Klampfl T, Harutyunyan AS, et al. JAK2 or CALR mutation status defines subtypes of essential thrombocythemia with substantially different clinical course and outcomes. Blood. 2014 Mar 6. 123 (10):1544-51. [Medline].
Mesa RA, Silverstein MN, Jacobsen SJ, Wollan PC, Tefferi A. Population-based incidence and survival figures in essential thrombocythemia and agnogenic myeloid metaplasia: an Olmsted County Study, 1976-1995. Am J Hematol. 1999 May. 61(1):10-5. [Medline]. [Full Text].
Tefferi A, Fonseca R, Pereira DL, Hoagland HC. A long-term retrospective study of young women with essential thrombocythemia. Mayo Clin Proc. 2001 Jan. 76(1):22-8. [Medline].
Girodon F, Bonicelli G, Schaeffer C, Mounier M, Carillo S, Lafon I, et al. Significant increase in the apparent incidence of essential thrombocythemia related to new WHO diagnostic criteria: a population-based study. Haematologica. 2009 Jun. 94(6):865-9. [Medline]. [Full Text].
[Guideline] Harrison CN, Butt N, Campbell P, Conneally E, Drummond M, Green AR, et al. Modification of British Committee for Standards in Haematology diagnostic criteria for essential thrombocythaemia. Br J Haematol. 2014 Nov. 167 (3):421-3. [Medline]. [Full Text].
Spanoudakis E, Margaritis D, Kotsianidis I, et al. Long-term bone marrow cultures (LTBMC) from essential thrombocythemia (ET) patients with or without JAK2617V>F mutation. Leuk Res. 2008 Oct. 32(10):1593-6. [Medline].
Teofili L, Martini M, Cenci T, et al. Epigenetic alteration of SOCS family members is a possible pathogenetic mechanism in JAK2 wild type myeloproliferative diseases. Int J Cancer. 2008 Oct 1. 123(7):1586-92. [Medline].
Ohyashiki K, Kodama A, Ohyashiki JH. Recurrent der(9;18) in essential thrombocythemia with JAK2 V617F is highly linked to myelofibrosis development. Cancer Genet Cytogenet. 2008 Oct. 186(1):6-11. [Medline].
Zhan H, Spivak JL. The diagnosis and management of polycythemia vera, essential thrombocythemia, and primary myelofibrosis in the JAK2 V617F era. Clin Adv Hematol Oncol. 2009 May. 7(5):334-42. [Medline].
Campbell PJ, Bareford D, Erber WN, Wilkins BS, Wright P, Buck G, et al. Reticulin accumulation in essential thrombocythemia: prognostic significance and relationship to therapy. J Clin Oncol. 2009 Jun 20. 27(18):2991-9. [Medline].
Riley CH, Brimnes MK, Hansen M, Jensen MK, Hasselbalch HC, Kjaer L, et al. Interferon-α induces marked alterations in circulating regulatory T cells, NK cell subsets and dendritic cells in patients with JAK2V617F -positive essential thrombocythemia and polycythemia vera. Eur J Haematol. 2015 Sep 19. [Medline].
Verger E, Cassinat B, Chauveau A, Dosquet C, Giraudier S, Schlageter MH, et al. Clinical and molecular response to interferon alpha therapy in essential thrombocythemia patients with CALR mutations. Blood. 2015 Oct 20. [Medline].
[Guideline] Barbui T, Barosi G, Grossi A, Gugliotta L, Liberato LN, Marchetti M, et al. Practice guidelines for the therapy of essential thrombocythemia. A statement from the Italian Society of Hematology, the Italian Society of Experimental Hematology and the Italian Group for Bone Marrow Transplantation. Haematologica. 2004 Feb. 89 (2):215-32. [Medline]. [Full Text].
Tefferi A, Barbui T. Polycythemia vera and essential thrombocythemia: 2015 update on diagnosis, risk-stratification and management. Am J Hematol. 2015 Feb. 90 (2):162-73. [Medline].
Tefferi A, Lasho TL, Begna KH, Patnaik MM, Zblewski DL, Finke CM, et al. A Pilot Study of the Telomerase Inhibitor Imetelstat for Myelofibrosis. N Engl J Med. 2015 Sep 3. 373 (10):908-19. [Medline].
Barosi G, Birgegard G, Finazzi G, Griesshammer M, Harrison C, Hasselbalch HC, et al. Response criteria for essential thrombocythemia and polycythemia vera: result of a European LeukemiaNet consensus conference. Blood. 2009 May 14. 113(20):4829-33. [Medline].
Gugliotta L, Marchioli R, Fiacchini M, et al. Epidemiological, diagnostic, therapeutic and prognostic aspects of essential thrombocythemia in a retrospective study of the GIMMC group in two thousand patients [abstract]. Blood. 1997. 90(suppl 1):348a.
Besses C, Cervantes F, Pereira A, et al. Major vascular complications in essential thrombocythemia: a study of the predictive factors in a series of 148 patients. Leukemia. 1999 Feb. 13(2):150-4. [Medline].
Cervantes F, Tassies D, Salgado C, et al. Acute transformation in nonleukemic chronic myeloproliferative disorders: actuarial probability and main characteristics in a series of 218 patients. Acta Haematol. 1991. 85(3):124-7. [Medline].
Chistolini A, Filoni V, Dragoni F, et al. Hepatitis C virus antibody in coagulopathic patients: ELISA and RIBA methods. Haematologica. 1993 Jul-Aug. 78(4):252-4. [Medline].
el-Kassar N, Hetet G, Brière J, Grandchamp B. Clonality analysis of hematopoiesis in essential thrombocythemia: advantages of studying T lymphocytes and platelets. Blood. 1997 Jan 1. 89(1):128-34. [Medline]. [Full Text].
Elliott MA, Tefferi A. Interferon-alpha therapy in polycythemia vera and essential thrombocythemia. Semin Thromb Hemost. 1997. 23(5):463-72. [Medline].
Emilia G, Sacchi S, Temperani P. Progression of essential thrombocythemia to blastic crisis via idiopathic myelofibrosis. Leuk Lymphoma. 1993 Mar. 9(4-5):423-6. [Medline].
Fabris F, Casonato A, Grazia del Ben M, De Marco L, Girolami A. Abnormalities of von Willebrand factor in myeloproliferative disease: a relationship with bleeding diathesis. Br J Haematol. 1986 May. 63(1):75-83. [Medline].
Jantunen R, Juvonen E, Ikkala E, et al. The predictive value of vascular risk factors and gender for the development of thrombotic complications in essential thrombocythemia. Ann Hematol. 2001 Feb. 80(2):74-8. [Medline].
Kobayashi S, Teramura M, Hoshino S, et al. Circulating megakaryocyte progenitors in myeloproliferative disorders are hypersensitive to interleukin-3. Br J Haematol. 1993 Apr. 83(4):539-44. [Medline].
Randi ML, Barbone E, Zerbinati P, et al. Essential thrombocythemia following polycythemia vera: an unusual sequence. J Med. 1996. 27(5-6):363-8. [Medline].
Shabbad E, Cassel A, Froom P, Aghai E. Effect of adherent cells on the regulation of BFU-E in patients with myeloproliferative disease. Am J Hematol. 1990 Apr. 33(4):225-9. [Medline].
van Genderen PJ, Michiels JJ, van der Poel-van de Luytgaarde SC, van Vliet HH. Acquired von Willebrand disease as a cause of recurrent mucocutaneous bleeding in primary thrombocythemia: relationship with platelet count. Ann Hematol. 1994 Aug. 69(2):81-4. [Medline].
Zauli G, Visani G, Catani L, et al. Reduced responsiveness of bone marrow megakaryocyte progenitors to platelet-derived transforming growth factor beta 1, produced in normal amount, in patients with essential thrombocythaemia. Br J Haematol. 1993 Jan. 83(1):14-20. [Medline].