Thrombocytosis

Dame, Christof

doi:10.1002/9780470987001.ch24

Cited by 4 publications

(6 citation statements)

References 140 publications

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“… A consistent platelet count of more than 450 × 10 9 /l is widely accepted as the threshold for making a diagnosis of thrombocytosis (Cazzola, 2008; Vannucchi & Barbui, 2007). According to Dame (2006), thrombocytosis could be classified into mild (platelet counts: ≥450 – <700 × 10 9 /l), moderate (≥700 – <900 × 10 9 /l) or severe (≥900 × 10 9 /l). Thromboembolic or haemorrhagic complications had not been reported in any of the p.Pro106Leu homozygotes.…”

Section: Methodsmentioning

confidence: 99%

Familial thrombocytosis caused by the novel germ‐line mutation p.Pro106Leu in the MPL gene

El-Harith¹,

Roesl²,

Ballmaier³

et al. 2008

Br J Haematol

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Summary Familial thrombosis (FT) has been described as a rare autosomal‐dominant disorder, mostly caused by activating mutations of the thrombopoietin gene (THPO). Other cases of FT have been linked to one of two different germline mutations in the myeloproliferative leukaemia virus oncogene gene (MPL), which codes for the thrombopoietin receptor MPL. We studied an Arab family with two siblings with severe thrombocytosis by linkage analysis and obtained evidence for linkage to MPL. Sequencing revealed homozygosity for the novel MPL germline mutation p.Pro106Leu (c.317C > T) in the two siblings. Subsequently, homozygosity for p.Pro106Leu was identified in six further FT patients from three other Arab families. Of 18 heterozygous carriers, 14 had normal platelet counts, while four had mild thrombocytosis. Strong support for association of the novel MPL mutation p.Pro106Leu with development of familial thrombocytosis has been obtained. Overall, p.Pro106Leu was absent on 386 alleles of 193 healthy German controls and present on 14 of 426 alleles (3·3%) of 213 unrelated Arabs, which was statistically significantly different (P < 0·001, Fisher’s exact test). We assume that p.Pro106Leu is a frequent MPL mutation in the Arab population, leading to severe thrombocytosis in homozygotes and occasionally to mild thrombocytosis in heterozygotes. In the families described the mode of inheritance could be regarded as autosomal‐recessive with possible mild heterozygote manifestation rather than autosomal‐dominant with high penetrance as usually seen in FT.

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Section: Methodsmentioning

confidence: 99%

Familial thrombocytosis caused by the novel germ‐line mutation p.Pro106Leu in the MPL gene

El-Harith¹,

Roesl²,

Ballmaier³

et al. 2008

Br J Haematol

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“…One definition considers a count from 450-700x10 9 /L as mild thrombocytosis, 700-900x10 9 /L as moderate, and more than 900x10 9 /L as severe. 1 Counts over 1000x10 9 /L are considered extreme thrombocytosis. …”

Section: Thrombocytosis Definedmentioning

confidence: 99%

Primary thrombocytosis in children

et al. 2014

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Myeloproliferative neoplasms are uncommon disorders in children, for which we have limited understanding of the pathogenesis and optimal management. JAK2 and MPL mutations, while common drivers of myeloproliferative neoplasms in adult patients, are not clearly linked to pediatric disease. Management and clinical outcomes in adults have been well delineated with defined recommendations for risk stratification and treatment. This is not the case for pediatric patients, for whom there is neither a standard approach to workup nor any consensus regarding management. This review will discuss thrombocytosis in children, including causes of thrombocytosis in children, the limited knowledge we have regarding pediatric primary thrombocytosis, and our thoughts on potential risk stratification and management, and future questions to be answered by laboratory research and collaborative clinical study. ABSTRACT © F e r r a t a S t o r t i F o u n d a t i o ngenerally on control at the transcriptional level. 13 This rate depends upon TPO binding to its receptor, which in turn depends upon how many TPO-R bearing cells are accessible, as well as how many receptors they express.14 Low platelet counts will lead to decreased TPO clearance (less receptors in the circulation) and therefore increased levels of TPO; the reverse occurs with higher platelet counts, i.e. thrombocytosis. There are variations to this basic principal, for example in the setting of idiopathic thrombocytopenia (thrombocytopenia due to destruction). In these cases, the number of megakaryocytes and megakaryocyte mass may also influence TPO regulation and circulating levels. 15,16 Causes of reactive thrombocytosis in childrenSecondary, or reactive, thrombocytosis is a common occurrence in children. It has been reported to occur in 6-15% of hospitalized children, with variations based on age. Most of these children had thrombocytosis that could be characterized as mild, but others transiently reached levels over 900,000. [17][18][19][20] Causes of secondary thrombocytosis are many and varied (Table 1). Infection is the most common, including viral and bacterial pathogens, and both acute and chronic infections. Especially in children under one year of age, any infection seems capable of triggering a high platelet count. Inflammatory diseases, e.g. Kawasaki disease, rheumatoid arthritis, and inflammatory bowel disease, are commonly associated with reactive thrombocytosis, as are hypoxia, trauma, blood loss, and malignancy. 19,21,22 Iron deficiency also seems to be a frequent cause of secondary thrombocytosis. 20 It is believed that underlying mechanisms of secondary thrombocytosis can be explained by upregulation of TPO expression and resultant increased TPO levels. Hepatic TPO mRNA expression is increased with inflammation. Figure 1 shows our groups' proposed diagnostic algorithm for approaching patients with elevated platelets. Evaluation for secondary causes, such as iron deficiency or inflammatory or infectious disorders is conducted. Iron deficiency and othe...

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“…[2][3][4][5][6][7]9,20 Thromboembolic and hemorrhagic complications are rare in patients with reactive thrombocytosis and anti-platelet or cytoreductive treatments are not usually needed, unless other risks are identified. 20,21 Thrombocytosis can also be classified according to severity, as judged by the peak platelet count. To provide reporting consistency, Sutor proposed the following severity classification: mild thrombocytosis ¼ peak count between 500 000 and 700 000 ml À1 ; moderate thombocytosis ¼ 700 000 to 900 000 ml À1 ; severe thrombocytosis ¼ 900 000 to 1 000 000 ml À1 ; and extreme thrombocytosis X1 000 000 ml À1 .…”

Section: Extreme Thrombocytosis Se Wiedmeier Et Almentioning

confidence: 99%

“…Most children with reactive thrombocytosis have an infectious disease, 21 and many of these involve the respiratory tract. 2,4,5,27 Similarly, in our report, infections were associated with 46% of episodes, about half of which were respiratory.…”

Section: Extreme Thrombocytosis Se Wiedmeier Et Almentioning

confidence: 99%

“…Thrombocytosis has been reported in patients with hemolytic anemia or iron deficiency. [2][3][4][5][6][7]12,20,21,27,30,31 None of our four anemic patients had recognized hemolysis and all were thought to have the anemia of prematurity. Although elevated platelet counts have been observed in anemic patients receiving human recombinant erythropoietin, 32 none in our current study had received this medication.…”

Section: Extreme Thrombocytosis Se Wiedmeier Et Almentioning

confidence: 99%

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Thrombocytosis in neonates and young infants: a report of 25 patients with platelet counts of ⩾1 000 000 μl−1

et al. 2009

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Objective: Thrombocytosis has been reported in neonates and young infants, but little is known of its prevalence, timing of onset, associated conditions, sequelae and outcomes. To better understand this condition, we used the data repositories of a multi-hospital health-care system to identify all individuals p140 days old (20 weeks) who, during the past 6 years, had a platelet count of X1 000 000 ml À1 . Study Design:We identified all infants with extreme thrombocytosis (using the Sutor definition of a platelet count of X1 000 000 ml À1 ) during the period of January 2003 through December 2008 in any Intermountain Healthcare facility. We obtained the information provided in this report from electronic and paper records.Result: Among 40 471 infants who had one or more platelet counts performed in this period, 25 had extreme thrombocytosis. No cases were identified in the first week after birth, 40% were recognized between the second and fourth weeks and 40% between the fifth and eighth week. The prevalence of thrombocytosis had no relationship with birth weight or gestational age but a slight predominance of female patients (15/25) was noted. In all, 26 episodes were found among the 25 infants: 12 episodes involved an antecedent infectious disease, 8 had an antecedent surgical procedure, 4 had the anemia of prematurity and 1 each had congenital adrenal hyperplasia and opiate withdrawal syndrome. No pathological thromboses or hemorrhages or other sequelae were detected and all episodes resolved with no deaths. Conclusion:The thrombocytosis cases that we report were all consistent with reactive thrombocytosis (also known as secondary thrombocytosis); none seemed to be essential (primary) thrombocytosis. We speculate that the pathogenesis involves increased platelet production due to megakaryopoietic stimulators induced by an infectious or inflammatory condition. From this series and previous reports, young infants with platelet counts up to 1 300 000 ml À1 do not seem to have a significant risk of thrombotic or hemorrhagic problems, and do not generally require anti-platelet or cytoreductive treatment.

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Thrombocytosis

Cited by 4 publications

References 140 publications

Familial thrombocytosis caused by the novel germ‐line mutation p.Pro106Leu in the MPL gene

Familial thrombocytosis caused by the novel germ‐line mutation p.Pro106Leu in the MPL gene

Primary thrombocytosis in children

Thrombocytosis in neonates and young infants: a report of 25 patients with platelet counts of ⩾1 000 000 μl−1

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