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血小板減少症

著者: 尾田琢也 松尾小児科医院

監修: 野口善令 豊田地域医療センター 総合診療科

著者校正/監修レビュー済:2021/09/22
患者向け説明資料

概要・推奨   

  1. 急激な血小板減少をみたときには、薬剤性血小板減少症を疑い、新たに開始した薬剤を見直すことが勧められる。
  1. 基準値内の血小板数であっても、50%以上の減少がみられたときには、早期の原因検索を行うことが勧められる。
薬剤監修について:
オーダー内の薬剤用量は日本医科大学付属病院 薬剤部 部長 伊勢雄也 以下、林太祐、渡邉裕次、井ノ口岳洋、梅田将光による疑義照会のプロセスを実施、疑義照会の対象については著者の方による再確認を実施しております。
※薬剤中分類、用法、同効薬、診療報酬は、エルゼビアが独自に作成した薬剤情報であり、
著者により作成された情報ではありません。
尚、用法は添付文書より、同効薬は、薬剤師監修のもとで作成しております。
※薬剤情報の(適外/適内/⽤量内/⽤量外/㊜)等の表記は、エルゼビアジャパン編集部によって記載日時にレセプトチェックソフトなどで確認し作成しております。ただし、これらの記載は、実際の保険適用の査定において保険適用及び保険適用外と判断されることを保証するものではありません。また、検査薬、輸液、血液製剤、全身麻酔薬、抗癌剤等の薬剤は保険適用の記載の一部を割愛させていただいています。
(詳細はこちらを参照)
著者のCOI(Conflicts of Interest)開示:
尾田琢也 : 特に申告事項無し[2021年]
監修:野口善令 : 特に申告事項無し[2021年]

改訂のポイント:
  1. 定期レビューを行った。
  1. 新型コロナウイルス感染症(COVID-19)に対するアデノウイルスベクターワクチン(アストラゼネカ社)によるワクチン起因性血栓性血小板減少症 Vaccine-induced immune thrombotic thrombocytopenia (VITT)を追加した。

病態・疫学・診察

疫学情報・病態・注意事項  
  1. 血小板減少症は、正常の血小板数分布の下側2.5パーセンタイルを下回る場合と定義されており、血小板数の正常値下限は、150,000/μLとされる。血小板数により、軽度(血小板数100,000~150,000/μL)、中等度(血小板数50,000~99,000/μL)、重度(血小板数50,000未満)――の3つの重症度に分類される。質的な異常がなければ、血小板数が50,000/μLを下回らない限り、外傷や手術の際にも過剰な出血を来すことは少ない。また、血小板数が20,000~30,000/μLを下回らない限り、誘因なく出血することは少ない。しかし、血小板数が5,000~10,000/μLを下回った場合には、誘因なくしかも致死的となる出血を来す危険がある[1]
  1. このような目安があるものの、血小板数と出血危険性との関連は絶対的ではなく、安全な血小板数を決めるのは難しい。粘膜出血があれば、出血危険性が高いと判断する。
  1. 出血危険性を評価する際には、血小板機能異常や凝固異常の有無がないかどうかを確認することも重要である。
  1. 通常、血小板減少症の際には、出血危険性を考慮するが、一部の疾患では血栓症の危険性も考える必要がある。ヘパリン誘発性血小板減少症(動脈および静脈血栓)、抗リン脂質抗体症候群(動脈および静脈血栓)、播種性血管内凝固症候群(disseminated intravascular coagulation、DIC)(通常静脈血栓)、血栓性微小血管障害に分類される血栓性血小板減少性紫斑病(thrombotic thrombocytopenic purpura、TTP)、溶血性尿毒症症候群(hemolytic-uremic syndrome、HUS)、薬剤誘発性血栓性微小血管障害が代表例である。
  1. ワクチン起因性血栓性血小板減少症 Vaccine-induced immune thrombotic thrombocytopenia (VITT) は、新型コロナウイルス感染症(COVID-19)に対するアデノウイルスベクターワクチン(アストラゼネカ社)の稀な副反応である。ヘパリンの先行投与がないにも関わらず、ヘパリン誘発性血小板減少症と同様に動脈および静脈血栓を生じる。ワクチン投与後4〜28日後の発症に注意が必要である[2]
  1. 血小板は、骨髄で巨核球より作られ、全血小板のうち約1/3は脾臓にプールされている。8~10日の寿命を終えると、単球・マクロファージにより回収される。
  1. 血小板減少症は以下の3つのメカニズムにより引き起こされる。
  1. すなわち、①骨髄での産生減少、②脾臓での捕捉増加、③血小板破壊促進・消費、④輸液や輸血による希釈――である。
  1. 原因検索のためには、脾腫の有無を評価し、末梢血液塗抹標本の観察を行い、必要に応じて骨髄穿刺または骨髄生検を検討する。
  1. 偽性血小板減少症は、エデト酸(EDTA)を抗凝固薬として用いて採血を行った場合に、血小板が凝集したり、血小板が白血球へ付着したりしたために起こる検査上のアーチファクトである。
  1. 偽性血小板減少症は、病的意義はないが頻度はもっとも高い。抗凝固薬をエデト酸(EDTA)からクエン酸かヘパリンに変えて採血すると血小板数は正常化する。
  1. 骨髄での血小板産生減少は、幹細胞の障害や幹細胞の増殖を妨げるような障害で起こる。通常、複数の造血細胞系列に影響が及び、さまざまな程度の貧血や白血球減少を伴う。骨髄での巨核球細胞数の減少を確認できれば、診断できる。急性白血病、再生不良性貧血、悪性細胞の骨髄浸潤、骨髄線維症などの骨髄増殖性疾患、化学療法や放射線治療後、アルコール、ビタミンB12欠乏、葉酸欠乏、銅欠乏、ウイルス感染(HIV:human immunodeficiency virus、CMV:cytomegalovirus、EBV:Epstein-Barr virus、水痘など)などにより起こる。薬剤の反応として巨核球単独の減少を来し、血小板が減少することもある。免疫性血小板減少性紫斑病では、免疫性血小板減少以外に血小板産生障害によっても血小板が減少する。
  1. 脾臓での血小板捕捉増加は、脾腫により起こる。肝疾患に続発する門脈圧亢進症と骨髄増殖性およびリンパ増殖性疾患で起こる腫瘍細胞の脾臓浸潤などにより起こる。
  1. 血小板破壊促進・消費は、血管の異常、フィブリン血栓、血管内の人工物などが血小板の寿命を短縮させることで起こる非免疫性血小板減少症と、免疫学的機序を介してマクロファージの貪食により起こる免疫性血小板減少症がある。
  1. 非免疫性血小板減少症の原因として、敗血症、血管炎、血栓性血小板減少性紫斑病(thrombotic thrombocytopenic purpura、TTP)、溶血性尿毒症症候群(hemolytic-uremic syndrome、HUS)、播種性血管内凝固症候群(disseminated intravascular coagulation、DIC)、抗リン脂質抗体症候群、妊娠高血圧腎症(子癇前症)、子癇、HELLP症候群、体外循環、巨大海綿状血管腫などがある。
  1. 免疫性血小板減少症の原因として、ウイルスあるいは細菌感染、薬剤、免疫性血小板減少性紫斑病(immune thrombocytopenic purpura、ITP)などがある。
  1. 薬剤誘発性血小板減少症のメカニズムには、骨髄での血小板産生減少と免疫性血小板減少がある。
  1. 抗腫瘍薬や大量のアルコール摂取により骨髄での血小板産生が減少することがあり、この場合は薬剤中止後も数カ月続くことがある。
  1. 薬剤によっては免疫反応により血小板減少症を起こすことがあり、この場合は薬剤中止後5-7日以内に血小板数は回復することが多い。
  1. 血小板減少症は、全身性エリテマトーデス(SLE)や抗リン脂質抗体症候群などの膠原病や骨髄異形成症候群などの血液疾患の初期症状であることがある。
問診・診察のポイント  
問診:
  1. これまでに血小板減少を指摘されたことがあるか

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文献 

著者: J V Lacey, J A Penner
雑誌名: Semin Thromb Hemost. 1977 Jan;3(3):160-74.
Abstract/Text
PMID 322290  Semin Thromb Hemost. 1977 Jan;3(3):160-74.
著者: C A Schiffer, K C Anderson, C L Bennett, S Bernstein, L S Elting, M Goldsmith, M Goldstein, H Hume, J J McCullough, R E McIntyre, B L Powell, J M Rainey, S D Rowley, P Rebulla, M B Troner, A H Wagnon, American Society of Clinical Oncology
雑誌名: J Clin Oncol. 2001 Mar 1;19(5):1519-38.
Abstract/Text OBJECTIVE: To determine the most effective, evidence-based approach to the use of platelet transfusions in patients with cancer.
OUTCOMES: Outcomes of interest included prevention of morbidity and mortality from hemorrhage, effects on survival, quality of life, toxicity reduction, and cost-effectiveness.
EVIDENCE: A complete MedLine search was performed of the past 20 years of the medical literature. Keywords included platelet transfusion, alloimmunization, hemorrhage, threshold and thrombocytopenia. The search was broadened by articles from the bibliographies of selected articles.
VALUES: Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly related to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COST: The possible consequences of different approaches to the use of platelet transfusion were considered in evaluating a preference for one or another technique producing similar outcomes. Cost alone was not a determining factor.
RECOMMENDATIONS: Appendix A summarizes the recommendations concerning the choice of particular platelet preparations, the use of prophylactic platelet transfusions, indications for transfusion in selected clinical situations, and the diagnosis, prevention, and management of refractoriness to platelet transfusion.
VALIDATION: Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board reviewed this document.
SPONSOR: American Society of Clinical Oncology

PMID 11230498  J Clin Oncol. 2001 Mar 1;19(5):1519-38.
著者: British Committee for Standards in Haematology, Blood Transfusion Task Force
雑誌名: Br J Haematol. 2003 Jul;122(1):10-23.
Abstract/Text
PMID 12823341  Br J Haematol. 2003 Jul;122(1):10-23.
著者: Ambuj Kumar, Rahul Mhaskar, Brenda J Grossman, Richard M Kaufman, Aaron A R Tobian, Steven Kleinman, Terry Gernsheimer, Alan T Tinmouth, Benjamin Djulbegovic, AABB Platelet Transfusion Guidelines Panel
雑誌名: Transfusion. 2015 May;55(5):1116-27; quiz 1115. doi: 10.1111/trf.12943. Epub 2014 Nov 12.
Abstract/Text BACKGROUND: Platelet (PLT) transfusion is indicated either prophylactically or therapeutically to reduce the risk of bleeding or to control active bleeding. Significant uncertainty exists regarding the appropriate use of PLT transfusion and the optimal threshold for transfusion in various settings. We formulated 12 key questions to assess the role of PLT transfusion.
STUDY DESIGN AND METHODS: We performed a systematic review (SR) of randomized controlled trials (RCTs) and observational studies. A comprehensive search of PubMed, Web of Science, and Cochrane registry of controlled trials was performed. Methodologic quality of included studies was assessed and a meta-analysis was performed if more than two studies with similar designs were identified for a specific question.
RESULTS: Seventeen RCTs and 55 observational studies were included in the final SR. Results from RCTs showed a beneficial effect of prophylactic compared with therapeutic transfusion for the prevention of significant bleeding in patients with hematologic disorders undergoing chemotherapy or stem cell transplantation. We found no difference in significant bleeding events related to the PLT count threshold for transfusion or the dose of PLTs transfused. Overall methodologic quality of RCTs was moderate. Results from observational studies showed no evidence that PLT transfusion prevented significant bleeding in patients undergoing central venous catheter insertions, lumbar puncture, or other surgical procedures. The methodologic quality of observational studies was very low.
CONCLUSION: We provide a comprehensive assessment of evidence on the use of PLT transfusions in a variety of clinical settings. Our report summarizes current knowledge and identifies gaps to be addressed in future research.

© 2014 AABB.
PMID 25387589  Transfusion. 2015 May;55(5):1116-27; quiz 1115. doi: 10・・・
著者: Matthew A Warner, David Woodrum, Andrew Hanson, Darrell R Schroeder, Gregory Wilson, Daryl J Kor
雑誌名: Transfusion. 2017 Apr;57(4):890-898. doi: 10.1111/trf.13996. Epub 2017 Jan 28.
Abstract/Text BACKGROUND: Platelet (PLT) transfusion before interventional radiology procedures is commonly performed in patients with thrombocytopenia. However, it is unclear if PLT transfusion is associated with reduced bleeding complications.
STUDY DESIGN AND METHODS: This is a retrospective cohort study of adults undergoing interventional radiology procedures between January 1, 2009, and December 31, 2013. Baseline characteristics, coagulation variables, transfusion requirements, and procedural details were evaluated. Propensity-matched analyses were used to assess relationships between PLT transfusions and the outcomes of interest, including a primary outcome of periprocedural red blood cell (RBC) transfusion during the procedure or within the first 24 hours after procedure.
RESULTS: A total of 18,204 participants met inclusion criteria, and 2060 (11.3%) had a PLT count of not more than 100 × 109 /L before their procedure. Of these, 203 patients (9.9) received preprocedural PLTs. There was no significant difference in RBC requirements between those receiving or not receiving preprocedural PLTs in propensity-matched analysis (odds ratio [OR], 1.45; 95% confidence interval [CI], 0.95-2.21; p = 0.085). PLT transfusion was associated with increased rates of intensive care unit admission (OR [95% CI], 1.57 [1.07-2.32]; p = 0.022).
CONCLUSION: In patients with thrombocytopenia undergoing interventional radiology procedures, preprocedural PLT transfusion was not associated with reduced periprocedural RBC requirements. These findings suggest that prophylactic PLT transfusions are not warranted in nonbleeding patients with preprocedural PLT counts exceeding 50 × 109 /L. Future clinical trials are needed to further define relationships between prophylactic PLT administration and bleeding complications, especially at more severe levels of thrombocytopenia or in the presence of PLT dysfunction.

© 2016 AABB.
PMID 28130779  Transfusion. 2017 Apr;57(4):890-898. doi: 10.1111/trf.1・・・
著者: Lakshminarayanan Nandagopal, Muthu Veeraputhiran, Tania Jain, Ayman O Soubani, Charles A Schiffer
雑誌名: Transfusion. 2016 Feb;56(2):344-8. doi: 10.1111/trf.13348. Epub 2015 Oct 7.
Abstract/Text BACKGROUND: Prophylactic platelet (PLT) transfusions are often administered to patients before bronchoscopy or bronchoalveolar lavage (BAL) to prevent bleeding. There is a paucity of data to validate this approach, with a commonly suggested PLT transfusion threshold of fewer than 50 × 10(9) /L, largely based on expert opinion. We conducted a retrospective study on the incidence of bleeding complications in patients with thrombocytopenia undergoing bronchoscopy.
STUDY DESIGN AND METHODS: We identified 150 consecutive patients with PLT counts of not more than 100 × 10(9) /L who underwent bronchoscopy and/or BAL from January 2009 to May 2014 at our institution. The British Thoracic Society (BTS) guidelines were used to categorize bleeding associated with bronchoscopy.
RESULTS: Infection (40%) was the primary indication for bronchoscopy with BAL. Fifty-eight of 89 (65%) patients with baseline PLT counts of not more than 50 × 10(9) /L received prophylactic transfusions compared to 8% of those with PLT counts of more than 50 × 10(9) /L. The PLT count did not increase to more than 50 × 10(9) /L in many patients who received transfusions. Seventy-two patients had counts of less than 50 × 10(9) /L at the time of bronchoscopy, with 15 patients having counts of less than 20 × 10(9) /L. Only one patient with a PLT count of 61 × 10(9) /L had bleeding that required continuous suctioning but then resolved spontaneously (termed "mild bleeding" by BTS criteria). Bloody lavage that resolved spontaneously without continuous suctioning (termed "no bleeding" by the BTS criteria) was observed in nine (6%) patients.
CONCLUSION: The very low incidence of bleeding complications from bronchoscopy with or without BAL even in patients with PLT counts of not more than 30 × 10(9) /L (no episodes of clinically significant bleeding in 35 patients) demonstrates that bronchoscopy can be done safely in patients with severe thrombocytopenia.

© 2015 AABB.
PMID 26446048  Transfusion. 2016 Feb;56(2):344-8. doi: 10.1111/trf.133・・・
著者: Kristin Zeidler, Kornelius Arn, Oliver Senn, Urs Schanz, Georg Stussi
雑誌名: Transfusion. 2011 Nov;51(11):2269-76. doi: 10.1111/j.1537-2995.2011.03147.x. Epub 2011 Apr 22.
Abstract/Text BACKGROUND: Patients with severe thrombocytopenia are at risk for bleeding during insertion of central venous catheters (CVCs). Although most guidelines recommend preprocedural platelet (PLT) transfusions at a threshold of less than 50 × 10(9) /L, there is only weak evidence supporting such recommendations.
STUDY DESIGN AND METHODS: The current study aimed to establish a safe PLT transfusion trigger in patients with CVC placements. We performed a retrospective single-center analysis of 604 CVC insertions in 193 patients with acute leukemia receiving intensive chemotherapy or stem cell transplantation.
RESULTS: A total of 48% of the patients had a bleeding risk during CVC insertions, mostly due to thrombocytopenia. The bleeding incidence was 32% with 96% Grade 1 and 4% Grade 2 bleedings requiring prolonged local compression. There were no Grade 3 to 4 bleedings. Hemoglobin levels were similar before and 24 and 48 hours after the CVC insertion in the bleeding and nonbleeding group and there was no difference in the red blood cell (p = 0.72) and PLT transfusion requirements (p = 0.057) after CVC insertion. In multivariate analysis, only patients with PLT counts of less than 20 × 10(9) /L were at higher risk for bleeding before (p = 0.015) and after preprocedural PLT transfusions (p =0.006) compared to patients with PLT counts of 100 × 10(9) /L or more.
CONCLUSION: CVC placements can safely be performed in patients with PLT counts of 20 × 10(9) /L or more without preprocedural PLT transfusions.

© 2011 American Association of Blood Banks.
PMID 21517892  Transfusion. 2011 Nov;51(11):2269-76. doi: 10.1111/j.15・・・
著者: Joost J van Veen, Timothy J Nokes, Mike Makris
雑誌名: Br J Haematol. 2010 Jan;148(1):15-25. doi: 10.1111/j.1365-2141.2009.07899.x. Epub 2009 Sep 22.
Abstract/Text Neuraxial anaesthesia is increasingly performed in thrombocytopenic patients at the time of delivery of pregnancy. There is a lack of data regarding the optimum platelet count at which spinal procedures can be safely performed. Reports are often confounded by the presence of other risk factors for spinal haematomata, such as anticoagulants, antiplatelet agents and other acquired or congenital coagulopathies/platelet function defects or rapidly falling platelet counts. In the absence of these additional risk factors, a platelet count of 80 x 10(9)/l is a 'safe' count for placing an epidural or spinal anaesthetic and 40 x 10(9)/l is a 'safe' count for lumbar puncture. It is likely that lower platelet counts may also be safe but there is insufficient published evidence to make recommendations for lower levels at this stage. For patients with platelet counts of 50-80 x 10(9)/l requiring epidural or spinal anaesthesia and patients with a platelet count 20-40 x 10(9)/l requiring a lumbar puncture, an individual decision based on assessment of risks and benefits should be made.

PMID 19775301  Br J Haematol. 2010 Jan;148(1):15-25. doi: 10.1111/j.13・・・
著者: Stephan R Vavricka, Roland B Walter, Sarosh Irani, Joerg Halter, Urs Schanz
雑誌名: Ann Hematol. 2003 Sep;82(9):570-3. doi: 10.1007/s00277-003-0707-0. Epub 2003 Aug 2.
Abstract/Text No data exist on the trigger for platelet transfusions in adult thrombocytopenic patients with acute leukemia undergoing lumbar puncture (LP). We reviewed the records of 66 patients with acute leukemia (median age 38 years, range 18-68) who have been treated in our institution for 6 years. A total of 195 LPs were performed. No serious hemorrhagic complications occurred, but there was a significant trend towards a higher percentage of traumatic procedures, defined as the occurrence of >500 erythrocytes per high-power field, in patients with lowest platelet counts ( p<0.005). Although not associated with serious clinical bleeding events in this study, the increased occurrence of traumatic procedures may indicate an increased risk for more serious hemorrhagic complications, implying a trigger not lower than 20x10(9)/L for prophylactic transfusions of platelets in adult patients with acute leukemia undergoing LP.

PMID 12904898  Ann Hematol. 2003 Sep;82(9):570-3. doi: 10.1007/s00277-・・・
著者: Drew Provan, Roberto Stasi, Adrian C Newland, Victor S Blanchette, Paula Bolton-Maggs, James B Bussel, Beng H Chong, Douglas B Cines, Terry B Gernsheimer, Bertrand Godeau, John Grainger, Ian Greer, Beverley J Hunt, Paul A Imbach, Gordon Lyons, Robert McMillan, Francesco Rodeghiero, Miguel A Sanz, Michael Tarantino, Shirley Watson, Joan Young, David J Kuter
雑誌名: Blood. 2010 Jan 14;115(2):168-86. doi: 10.1182/blood-2009-06-225565. Epub 2009 Oct 21.
Abstract/Text Previously published guidelines for the diagnosis and management of primary immune thrombocytopenia (ITP) require updating largely due to the introduction of new classes of therapeutic agents, and a greater understanding of the disease pathophysiology. However, treatment-related decisions still remain principally dependent on clinical expertise or patient preference rather than high-quality clinical trial evidence. This consensus document aims to report on new data and provide consensus-based recommendations relating to diagnosis and treatment of ITP in adults, in children, and during pregnancy. The inclusion of summary tables within this document, supported by information tables in the online appendices, is intended to aid in clinical decision making.

PMID 19846889  Blood. 2010 Jan 14;115(2):168-86. doi: 10.1182/blood-20・・・
著者: Cindy Neunert, Wendy Lim, Mark Crowther, Alan Cohen, Lawrence Solberg, Mark A Crowther, American Society of Hematology
雑誌名: Blood. 2011 Apr 21;117(16):4190-207. doi: 10.1182/blood-2010-08-302984. Epub 2011 Feb 16.
Abstract/Text Immune thrombocytopenia (ITP) is commonly encountered in clinical practice. In 1996 the American Society of Hematology published a landmark guidance paper designed to assist clinicians in the management of this disorder. Since 1996 there have been numerous advances in the management of both adult and pediatric ITP. These changes mandated an update in the guidelines. This guideline uses a rigorous, evidence-based approach to the location, interpretation, and presentation of the available evidence. We have endeavored to identify, abstract, and present all available methodologically rigorous data informing the treatment of ITP. We provide evidence-based treatment recommendations using the GRADE system in those areas in which such evidence exists. We do not provide evidence in those areas in which evidence is lacking, or is of lower quality--interested readers are referred to a number of recent, consensus-based recommendations for expert opinion in these clinical areas. Our review identified the need for additional studies in many key areas of the therapy of ITP such as comparative studies of "front-line" therapy for ITP, the management of serious bleeding in patients with ITP, and studies that will provide guidance about which therapy should be used as salvage therapy for patients after failure of a first-line intervention.

PMID 21325604  Blood. 2011 Apr 21;117(16):4190-207. doi: 10.1182/blood・・・
著者: Jessica A Reese, Jennifer D Peck, David R Deschamps, Jennifer J McIntosh, Eric J Knudtson, Deirdra R Terrell, Sara K Vesely, James N George
雑誌名: N Engl J Med. 2018 Jul 5;379(1):32-43. doi: 10.1056/NEJMoa1802897.
Abstract/Text BACKGROUND: Platelet counts of less than 150,000 per cubic millimeter during uncomplicated pregnancies are described as gestational thrombocytopenia if no alternative cause is identified. Platelet counts may be even lower in women with pregnancy-related complications. However, the occurrence and severity of thrombocytopenia throughout pregnancy are not defined.
METHODS: We evaluated platelet counts throughout pregnancy in women who delivered at Oklahoma University Medical Center between 2011 and 2014. These platelet counts were compared with those of nonpregnant women who were included in the National Health and Nutrition Examination Survey from 1999 through 2012.
RESULTS: Among the 15,723 deliveries that occurred during the study period, 7351 women had sufficient data for our analyses. Of these women, 4568 had uncomplicated pregnancies, 2586 had pregnancy-related complications, and 197 had preexisting disorders associated with thrombocytopenia. Among the women who had uncomplicated pregnancies, the mean platelet count in the first trimester (mean gestation, 8.7 weeks) was 251,000 per cubic millimeter, which was lower than the mean platelet count in the 8885 nonpregnant women (273,000 per cubic millimeter) (P<0.001). At the time of delivery, 9.9% of the women with uncomplicated pregnancies had a platelet count below 150,000 per cubic millimeter. During the course of the uncomplicated pregnancies and deliveries, only 45 women (1.0%) had a platelet count below 100,000 per cubic millimeter. Among the 12 women with uncomplicated pregnancies who had a platelet count below 80,000 per cubic millimeter, only 5 (0.1%, among whom the range of platelet counts was 62,000 to 78,000 per cubic millimeter; median, 65,000) were identified by medical record review as having no alternative cause for the thrombocytopenia. Platelet counts of less than 150,000 per cubic millimeter at the time of delivery were more common among women who had pregnancy-related complications than among women who had uncomplicated pregnancies (11.9% vs. 9.9%, P=0.01). Throughout their pregnancies and deliveries, 59 women (2.3%) with pregnancy-related complications had a platelet count below 100,000 per cubic millimeter, and 31 (1.2%) had a platelet count below 80,000 per cubic millimeter.
CONCLUSIONS: Mean platelet counts decreased during pregnancy in all the women, beginning in the first trimester. In women who have a platelet count of less than 100,000 per cubic millimeter, a cause other than pregnancy or its complications should be considered. (Funded by the National Heart, Lung, and Blood Institute.).

PMID 29972751  N Engl J Med. 2018 Jul 5;379(1):32-43. doi: 10.1056/NEJ・・・
著者: C L Balduini, A Savoia, M Seri
雑誌名: J Thromb Haemost. 2013 Jun;11(6):1006-19. doi: 10.1111/jth.12196.
Abstract/Text The diagnosis of inherited thrombocytopenias is difficult, for many reasons. First, as they are all rare diseases, they are little known by clinicians, who therefore tend to suspect the most common forms. Second, making a definite diagnosis often requires complex laboratory techniques that are available in only a few centers. Finally, half of the patients have forms that have not yet been described. As a consequence, many patients with inherited thrombocytopenias are misdiagnosed with immune thrombocytopenia, and are at risk of receiving futile treatments. Misdiagnosis is particularly frequent in patients whose low platelet count is discovered in adult life, because, in these cases, even the inherited origin of thrombocytopenia may be missed. Making the correct diagnosis promptly is important, as we recently learned that some forms of inherited thrombocytopenia predispose to other illnesses, such as leukemia or kidney failure, and affected subjects therefore require close surveillance and, if necessary, prompt treatments. Moreover, medical treatment can increase platelet counts in specific disorders, and affected subjects can therefore receive drugs instead of platelet transfusions when selective surgery is required. In this review, we will discuss how to suspect, diagnose and manage inherited thrombocytopenias, with particular attention to the forms that frequently present in adults. Moreover, we describe four recently identified disorders that belong to this group of disorders that are often diagnosed in adults: MYH9-related disease, monoallelic Bernard-Soulier syndrome, ANKRD26-related thrombocytopenia, and familial platelet disorder with predisposition to acute leukemia.

© 2013 International Society on Thrombosis and Haemostasis.
PMID 23510089  J Thromb Haemost. 2013 Jun;11(6):1006-19. doi: 10.1111/・・・
著者: Patrizia Noris, Catherine Klersy, Paolo Gresele, Fiorina Giona, Paola Giordano, Pietro Minuz, Giuseppe Loffredo, Alessandro Pecci, Federica Melazzini, Elisa Civaschi, Annamaria Mezzasoma, Monica Piedimonte, Fabrizio Semeraro, Dino Veneri, Francesco Menna, Laura Ciardelli, Carlo L Balduini, Italian Gruppo di Studio delle Piastrine
雑誌名: Br J Haematol. 2013 Jul;162(1):112-9. doi: 10.1111/bjh.12349. Epub 2013 Apr 25.
Abstract/Text The most frequent forms of inherited thrombocytopenia (IT) are characterized by platelet size abnormalities and it has been suggested that this parameter is useful for their differentiation from immune thrombocytopenia (ITP). Recently, a monocentric study identified cut-off values for mean platelet volume (MPV) and mean platelet diameter (MPD) with good diagnostic accuracy in this respect. To validate these cut-off values in a different and larger case series of patients, we enrolled 130 subjects with ITP and 113 with IT in six different centres. The platelet count and MPV was each measured by the instrument routinely used in each institution. In some centres, platelet count was also measured by optical microscopy. MPD was evaluated centrally by image analysis of peripheral blood films. The previously identified cut-off value for MPV had 91% specificity in distinguishing ITP from inherited macrothrombocytopenias (mono and biallelic Bernard-Soulier, MYH9-related disease), while its sensitivity was greatly variable depending on the instrument used. With an appropriate instrument, specificity was 83%. The diagnostic accuracy of MPD was lower than that obtained with MPV. We concluded that MPV is a useful parameter for differentiating ITP from IT provided that it is measured by appropriate cell counters.

© 2013 John Wiley & Sons Ltd.
PMID 23617394  Br J Haematol. 2013 Jul;162(1):112-9. doi: 10.1111/bjh.・・・
著者: Donald M Arnold, Ishac Nazy, Rumi Clare, Anushka M Jaffer, Brandon Aubie, Na Li, John G Kelton
雑誌名: Blood Adv. 2017 Nov 28;1(25):2414-2420. doi: 10.1182/bloodadvances.2017010942. Epub 2017 Nov 28.
Abstract/Text Nonspecific diagnostic criteria and uncertain estimates of severe bleeding events are fundamental gaps in knowledge of primary immune thrombocytopenia (ITP). To address these issues, we created the McMaster ITP Registry. In this report, we describe the methodology of the registry, the process for arriving at the diagnosis, and the frequency of bleeding. Consecutive patients with platelets <150 × 109/L from a tertiary hematology clinic in Canada were eligible. Patients completed a panel of investigations and were managed per clinical need. Two hematologists initially determined the cause of the thrombocytopenia using standard criteria and reevaluated the diagnosis over time, which was adjudicated at regular team meetings. Bleeding was graded from 0 (none) to 2 (severe) prospectively using an ITP-specific tool. Data were validated by duplicate chart review and source verification. Between 2010 and 2016, 614 patients were enrolled. Median follow-up for patients with >1 visit was 1.7 years (interquartile range, 0.8-3.4). At registration, 295 patients were initially diagnosed with primary ITP; of those, 36 (12.2%) were reclassified as having a different diagnosis during follow-up. At registration, 319 patients were initially diagnosed with another thrombocytopenic condition; of those, 10 (3.1%) were ultimately reclassified as having primary ITP. Of 269 patients with a final diagnosis of primary ITP, 56.5% (95% confidence interval [CI], 50.4-62.5] experienced grade 2 bleeding at 1 or more anatomical site, and 2.2% (95% CI, 0.8-4.8) had intracranial hemorrhage. Nearly 1 in 7 patients with primary ITP were misdiagnosed. Grade 2 bleeding was common. Registry data can help improve the clinical and laboratory classification of patients with ITP.

PMID 29296891  Blood Adv. 2017 Nov 28;1(25):2414-2420. doi: 10.1182/bl・・・
著者: S Vanderschueren, A De Weerdt, M Malbrain, D Vankersschaever, E Frans, A Wilmer, H Bobbaers
雑誌名: Crit Care Med. 2000 Jun;28(6):1871-6.
Abstract/Text OBJECTIVE: To study the incidence and prognosis of thrombocytopenia in adult intensive care unit (ICU) patients.
DESIGN: Prospective observational cohort study.
SETTING: The medical ICU of a university hospital and the combined medical-surgical ICU of a regional hospital.
PATIENTS: All patients consecutively admitted during a 5-month period.
INTERVENTIONS: Patient surveillance and data collection.
MEASUREMENTS AND MAIN RESULTS: The primary outcome measure was ICU mortality. Data of 329 patients were analyzed. Overall ICU mortality rate was 19.5%. A total of 136 patients (41.3%) had at least one platelet count <150 x 10(9)/L. These patients had higher Multiple Organ Dysfunction Score (MODS), Simplified Acute Physiology Score (SAPS) II, and Acute Physiology and Chronic Health Evaluation (APACHE) II scores at admission, longer ICU stay (8 [4-16] days vs. 5 [2-9] days) (median [interquartile range]), and higher ICU mortality (crude odds ratio [OR], 5.0; 95% confidence interval [CI], 2.7-9.1) and hospital mortality than patients with daily platelet counts >150 x 10(9)/L (p < .0005 for all comparisons). Bleeding incidence rose from 4.1% in nonthrombocytopenic patients to 21.4% in patients with minimal platelet counts between 101 x 10(9)/L and 149 x 10(9)/L (p = .0002) and to 52.6% in patients with minimal platelet counts <100 x 10(9)/L (p < .0001). In all quartiles of admission APACHE II and SAPS II scores, a nadir platelet count <150 x 10(9)/L was related with a substantially poorer vital prognosis. Similarly, a drop in platelet count to < or =50% of admission was associated with higher death rates (OR, 6.0; 95% CI, 3.0-12.0; p < .0001). In a logistic regression analysis with ICU mortality as the dependent variable, the occurrence of thrombocytopenia had more explanatory power than admission variables, including APACHE II, SAPS II, and MODS scores (adjusted OR, 4.2; 95% CI, 1.8-10.2).
CONCLUSIONS: Thrombocytopenia is common in ICUs and constitutes a simple and readily available risk marker for mortality, independent of and complementary to established severity of disease indices. Both a low nadir platelet count and a large fall of platelet count predict a poor vital outcome in adult ICU patients.

PMID 10890635  Crit Care Med. 2000 Jun;28(6):1871-6.
著者: Jennifer L Priziola, Maureen A Smythe, William E Dager
雑誌名: Crit Care Med. 2010 Jun;38(6 Suppl):S145-54. doi: 10.1097/CCM.0b013e3181de0b88.
Abstract/Text Thrombocytopenia occurs in 15% to 58% of intensive care unit patients. The incidence varies based upon patient population, timing and frequency of platelet monitoring, and definition of thrombocytopenia. Up to 25% of acutely ill patients develop drug-induced thrombocytopenia. When drug-induced thrombocytopenia is suspected, nondrug related causes must be evaluated and excluded. Establishing the diagnosis of drug-induced thrombocytopenia is challenging, as hundreds of medications have been implicated. Medications commonly associated with drug-induced thrombocytopenia include glycoprotein IIb/IIIa inhibitors, cinchona alkaloids, antibiotics, anticonvulsants, and heparin. Once the diagnosis is suspected, clinicians should identify the start date of medications to assess the timeline of development. The likelihood of each medication causing thrombocytopenia must be evaluated. The risk vs. benefit of discontinuing the suspected medication and availability of alternative medications must be assessed. The role of corticosteroids, immune globulin, and plasmapheresis is uncertain. Once the offending agent has been discontinued, the overall prognosis is excellent. In the case of suspected or confirmed heparin-induced thrombocytopenia, an alternative anticoagulant should be initiated. Drug-induced thrombocytopenia should be documented in the medical record and reported according to institutional and national standards. This review focuses on immune-mediated drug-induced thrombocytopenia from medications commonly utilized in the critically ill patient.

PMID 20502168  Crit Care Med. 2010 Jun;38(6 Suppl):S145-54. doi: 10.10・・・
著者: M F Buckley, J W James, D E Brown, G S Whyte, M G Dean, C N Chesterman, J A Donald
雑誌名: Thromb Haemost. 2000 Mar;83(3):480-4.
Abstract/Text This is the first report of a method to assess the significance of numerical changes in the platelet count based upon a result exceeding the normal intra-individual variation in platelet numbers. Serial platelet counts from 3,789 subjects were analysed to determine the intra-individual variation in platelet numbers. A platelet count difference of 98 x 10(9)/L in males was found to represent a change that would occur by chance in less than 1 in 1,000 platelet count determinations. Tables to determine the significance of platelet number variations, given N previous observations, are provided at two probability levels. The repeatability of the platelet count was calculated as 0.871 (males) and 0.849 (females) indicating that the heritability of platelet count is high and that the platelet count is predominantly genetically determined. A seasonal variation in platelet count was found with a 'winter' versus 'summer' difference of 5.10 X 10(9)/L (males) and 5.82 x 10(9)/L (females).

PMID 10744157  Thromb Haemost. 2000 Mar;83(3):480-4.

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