Polycythemia vera laboratory tests: Difference between revisions
(Created page with "{{CMG}} {{Polycythemia vera}} ==Overview== '''Primary polycythemia''', often called '''polycythemia vera''' (PCV), polycythemia rubra vera (PRV), or erythremia, occur...") |
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==Overview== | ==Overview== | ||
'''Primary [[polycythemia]]''', often called '''[[polycythemia vera]]''' (PCV), polycythemia rubra vera (PRV), or erythremia, occurs when excess red blood cells are produced as a result of an abnormality of the [[bone marrow]]. Often, excess [[white blood cell]]s and [[platelet]]s are also produced. Polycythemia vera is classified as a [[myeloproliferative disease]]. | '''Primary [[polycythemia]]''', often called '''[[polycythemia vera]]''' (PCV), polycythemia rubra vera (PRV), or erythremia, occurs when excess red blood cells are produced as a result of an abnormality of the [[bone marrow]]. Often, excess [[white blood cell]]s and [[platelet]]s are also produced. Polycythemia vera is classified as a [[myeloproliferative disease]]. | ||
==Lab tests== | |||
Patients with polycythemia vera may often be [[asymptomatic]]. Physical exam findings are non-specific, but may include [[hepatosplenomegaly|enlarged liver or spleen]], [[plethora]], or [[tophus|gouty nodules]]. The diagnosis is often suspected on the basis of laboratory tests. Common findings include an elevated hemoglobin level or [[hematocrit]], reflecting the increased number of red blood cells; the [[platelet count]] or [[white blood cell count]] may also be increased. Because polycythemia vera results from an essential increase in erythrocyte production, patients have a low erythropoietin (EPO) level. | |||
In primary polycythemia, there may be 8 to 9 million and occasionally 11 million erythrocytes per cubic millimeter of blood (a normal range for adults is 4-6), and the [[hematocrit]] may be as high as 70 to 80%. In addition, the total blood volume sometimes increases to as much as twice normal. The entire vascular system can become markedly engorged with blood, and circulation times for blood throughout the body can increase up to twice the normal value. The increased numbers of [[erythrocyte]]s can cause the [[viscosity]] of the blood to increase as much as five times normal. Capillaries can become plugged by the very viscous blood, and the flow of blood through the vessels tends to be extremely sluggish. | |||
Recently, in 2005, a mutation in the [[JAK2]] kinase (V617F) was found by multiple research groups <ref>{{cite journal | author=Baxter EJ, Scott LM, Campbell PJ, East C, Fourouclas N, Swanton S, Vassiliou GS, Bench AJ, Boyd EM, Curtin N, Scott MA, Erber WN, Green AR | title=Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders | journal=Lancet | year=2005 | pages=1054-61 | volume=365 | issue=9464 | id=PMID 15781101}}</ref><ref>{{cite journal | author=Levine RL, Wadleigh M, Cools J, Ebert BL, Wernig G, Huntly BJ, Boggon TJ, Wlodarska I, Clark JJ, Moore S, Adelsperger J, Koo S, Lee JC, Gabriel S, Mercher T, D'Andrea A, Frohling S, Dohner K, Marynen P, Vandenberghe P, Mesa RA, Tefferi A, Griffin JD, Eck MJ, Sellers WR, Meyerson M, Golub TR, Lee SJ, Gilliland DG | title=Activating mutation in the tyrosine kinase JAK2 in polycythemia vera, essential thrombocythemia, and myeloid metaplasia with myelofibrosis | journal=Cancer Cell | year=2005 | pages=387-97 | volume=7 | issue=4 | id=PMID 15837627}}</ref> to be strongly associated with polycythemia vera. ''JAK2'' is a member of the [[Janus kinase]] family. This mutation may be helpful in making a diagnosis or as a target for future therapy. | |||
As a consequence of the above, people with untreated PV are at a risk of various [[thrombosis|thrombotic]] events ([[deep venous thrombosis]], [[pulmonary embolism]]), [[myocardial infarction|heart attack]] and [[stroke]], and have a substantial risk of [[Budd-Chiari syndrome]] (hepatic vein thrombosis), or [[Myelofibrosis]]. The condition is considered chronic; no cure exists. Symptomatic treatment (see below) can normalize the blood count and most patients can live a normal life for years. | |||
==References== | ==References== | ||
Revision as of 16:13, 21 January 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Primary polycythemia, often called polycythemia vera (PCV), polycythemia rubra vera (PRV), or erythremia, occurs when excess red blood cells are produced as a result of an abnormality of the bone marrow. Often, excess white blood cells and platelets are also produced. Polycythemia vera is classified as a myeloproliferative disease.
Lab tests
Patients with polycythemia vera may often be asymptomatic. Physical exam findings are non-specific, but may include enlarged liver or spleen, plethora, or gouty nodules. The diagnosis is often suspected on the basis of laboratory tests. Common findings include an elevated hemoglobin level or hematocrit, reflecting the increased number of red blood cells; the platelet count or white blood cell count may also be increased. Because polycythemia vera results from an essential increase in erythrocyte production, patients have a low erythropoietin (EPO) level.
In primary polycythemia, there may be 8 to 9 million and occasionally 11 million erythrocytes per cubic millimeter of blood (a normal range for adults is 4-6), and the hematocrit may be as high as 70 to 80%. In addition, the total blood volume sometimes increases to as much as twice normal. The entire vascular system can become markedly engorged with blood, and circulation times for blood throughout the body can increase up to twice the normal value. The increased numbers of erythrocytes can cause the viscosity of the blood to increase as much as five times normal. Capillaries can become plugged by the very viscous blood, and the flow of blood through the vessels tends to be extremely sluggish.
Recently, in 2005, a mutation in the JAK2 kinase (V617F) was found by multiple research groups [1][2] to be strongly associated with polycythemia vera. JAK2 is a member of the Janus kinase family. This mutation may be helpful in making a diagnosis or as a target for future therapy.
As a consequence of the above, people with untreated PV are at a risk of various thrombotic events (deep venous thrombosis, pulmonary embolism), heart attack and stroke, and have a substantial risk of Budd-Chiari syndrome (hepatic vein thrombosis), or Myelofibrosis. The condition is considered chronic; no cure exists. Symptomatic treatment (see below) can normalize the blood count and most patients can live a normal life for years.
References
- ↑ Baxter EJ, Scott LM, Campbell PJ, East C, Fourouclas N, Swanton S, Vassiliou GS, Bench AJ, Boyd EM, Curtin N, Scott MA, Erber WN, Green AR (2005). "Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders". Lancet. 365 (9464): 1054–61. PMID 15781101.
- ↑ Levine RL, Wadleigh M, Cools J, Ebert BL, Wernig G, Huntly BJ, Boggon TJ, Wlodarska I, Clark JJ, Moore S, Adelsperger J, Koo S, Lee JC, Gabriel S, Mercher T, D'Andrea A, Frohling S, Dohner K, Marynen P, Vandenberghe P, Mesa RA, Tefferi A, Griffin JD, Eck MJ, Sellers WR, Meyerson M, Golub TR, Lee SJ, Gilliland DG (2005). "Activating mutation in the tyrosine kinase JAK2 in polycythemia vera, essential thrombocythemia, and myeloid metaplasia with myelofibrosis". Cancer Cell. 7 (4): 387–97. PMID 15837627.