Contents

Disclaimer

Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check the product information and clinical procedures with the most up to date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The authors and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work. Except where otherwise stated, drug dosages and recommendations are for the non-pregnant adult who is not breastfeeding.

Show Summary Details
Page of

The polycythaemias 

The polycythaemias
Chapter:
The polycythaemias
Author(s):

Daniel Aruch

, and Ronald Hoffman

DOI:
10.1093/med/9780198746690.003.0517
Page of

PRINTED FROM OXFORD MEDICINE ONLINE (www.oxfordmedicine.com). © Oxford University Press, 2021. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy and Legal Notice).

date: 27 February 2021

Polycythaemia or erythrocytosis is characterized by an abnormal increase in the numbers of red blood cells, leading to an elevation in the haemoglobin concentration and haematocrit (>49% in men and >48% in women). The cause may be either (1) primary—due to an intrinsic defect of haematopoietic stem cells; or (2) secondary—due to extrinsic stimulation of progenitor erythroid cells by circulating growth factors; and the condition needs to be distinguished from (3) pseudopolycythaemia—in which haematocrit is raised because the plasma volume is decreased. Secondary polycythaemias: associated with appropriate erythropoietin secretion—conditions that are ultimately the result of tissue hypoxia and subsequent excessive erythropoietin production include (1) living at high altitude, (2) chronic lung disease, (3) cyanotic congenital heart disease with right-to-left shunting, (4) carbon monoxide intoxication—as occurs in heavy smokers, (5) haemoglobin variants with increased oxygen affinity, and (6) mutations in genes involved in the oxygen sensing pathway. Associated with inappropriate erythropoietin secretion—in the absence of tissue hypoxia, inappropriate erythropoietin production commonly originates from the kidney and many renal disorders are associated with erythrocytosis. Tumour-associated polycythaemia may also result from cerebellar haemangioblastoma, hepatocellular carcinoma, phaeochromocytoma, and other adrenal tumours. Primary polycythaemia: polycythaemia vera—is a clonal, chronic progressive haematological malignancy characterized by excessive proliferation of erythroid, myeloid, and megakaryocytic elements in the bone marrow. Aetiology—up to 95% of cases are caused by somatic mutations in the pluripotent haemopoietic stem cells leading to replacement of a key valine residue by phenylalanine at position 617 of the JAK2 kinase (V617F), which releases it from autoinhibition. Less common mutations have been described recently, primarily JAK2 exon 12 and LNK mutations.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can't find the answer there, please contact us.