1. THE MERCK MANUAL, Sec. 11, Ch. 133, Platelet Disorders Section 11. Hematology And Oncology hyperlink to list of chapters in currentsection. Chapter 133. platelet disorders. Topics. General. Thrombocytopenia. http://www.merck.com/pubs/mmanual/section11/chapter133/133a.htm

This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 11. Hematology And Oncology Chapter 133. Platelet Disorders Topics [General] Thrombocytopenia Platelet Dysfunction [General] Platelet disorders may cause defective formation of hemostatic plugs and bleeding because of decreased platelet numbers (thrombocytopenia) or because of decreased function despite adequate platelet numbers (platelet dysfunction).

2. June 2002 - Chasing After The Causes Of Platelet Disorders - CAP Today Chasing after the causes of platelet disorders George Corcoran, MD, and Kandice KottkeMarchant, MD, PhD The following article was adapted from the Archives of Pathology Laboratory Medicine (2002;126133-146). http://www.cap.org/captoday/archive/2002/platelet_disorders_feature.html

June 2002 Feature Story Chasing after the causes of platelet disorders George Corcoran, MD, and Kandice Kottke-Marchant, MD, PhD The following article was adapted from the Multiple etiologies exist for platelet-derived bleeding disorders. The laboratory evaluation of these disorders can range from simple to complex and should initially include a thorough evaluation of the patient's medical history, concentrating on personal and familial bleeding disorders and current medications. With this as a starting point, the algorithms presented here may be helpful in elucidating the underlying etiology for platelet-derived bleeding. Role of platelets in hemostasis Platelets are small (2 µm-diameter), non-nucleated blood cells produced in the bone marrow from megakaryocytes. They are rapidly activated by blood vessel injury and are a crucial component of the primary hemostatic response. In their unactivated state, platelets are roughly discoid in shape and contain cytoplasmic organelles, cytoskeletal elements, invaginating open-canalicular membrane systems, and platelet-specific granules called alpha and dense granules. Platelets have numerous intrinsic glycoproteins attached to the outer surface of their plasma membrane that are receptors for such ligands as fibrinogen, collagen, thrombin, and thrombospondin to von Willebrand factor and fibronectin. Platelets promote hemostasis by the following interconnected mechanisms: adhering to sites of vascular injury or artificial surfaces releasing compounds from their granules

3. Neonatal Platelet Disorders Discusses causes, symptoms, diagnosis and treatment of these disorders that interfere with the proper process of blood clot formation. In diagnosing platelet function disorders, specific tests are needed to determine whether the problem is caused by low http://neonatal.peds.washington.edu/NICU-WEB/platelets.stm

University of Washington Academic Medical Center Children's Hospital and Regional Medical Center Neonatal Platelet Disorders Authors Created Reviewed Revised This file requires Adobe Acrobat Reader. If you do not have Adobe Acrobat Reader installed, you may download a copy here Neonatal Platelet Disorders Authors About NICU-WEB Authorship Primary Author Thomas Strandjord, M.D. Associate Professor Contributing Authors Christine Gleason, M.D. Professor Alan Hodson, M.D. Professor Craig Jackson, M.D. Professor Dennis Mayock, M.D. Associate Professor Janet Murphy, M.D. Associate Professor Peter Tarczy-Hornoch, M.D. Associate Professor David Woodrum, M.D. Professor Web Mildred Hill EMAIL feedback regarding this document

4. Adults With Platelet Disorders TOC Discussion Teens with platelet disorders The purpose of this discussion group is to foster supportive dialog about the subject of ITP and other platelet disorders. Please follow the Netiquette Guidelines. Happy National Platelet Week Everybody! Christina 25 Jun 2002. Re Happy National Platelet Week Everybody! Amanda 28 Jun Re Happy National Platelet Week Everybody! Christina 30 http://www.pdsa.org/archive1t

About Us Contact Us Publications Guest Book ... Home Discussion - Teens with Platelet Disorders Contents Search Post Welcome! The purpose of this discussion group is to foster supportive dialog about the subject of ITP and other platelet disorders. Please follow the Netiquette Guidelines The views expressed on the discussion area and resultant communications are those of the contributors and not necessarily the views of PDSA. We assume no responsibility for any actions taken as a result of this information. For advice on your unique medical condition, please consult your health care professional. New to ITP? Read our FAQ Pregnant? Go to our pregnancy site See prior discussion group posts in our archives. CONTENTS Note: you may need to reload this page to see the most recent additions. I have had it for 24 years and still going strong Tommy 04 Feb 2003 on the headache thing kristen 25 Nov 2002 Headaches with ITP Anthony's Mom 20 Nov 2002 New Mom to the site - spleenectomy for an athlete Beth 15 Nov 2002 Re: just to say i am still alive...

5. EMedicine - Platelet Disorders : Article Excerpt By: Perumal Thiagarajan, MD Excerpt from platelet disorders. Synonyms, Key Words, and Related Terms autoimmune thrombocytopenia, alloimmune http://www.emedicine.com/med/byname/platelet-disorders.htm

(advertisement) Excerpt from Platelet Disorders Synonyms, Key Words, and Related Terms: autoimmune thrombocytopenia, alloimmune thrombocytopenia, drug-induced thrombocytopenia, thrombotic thrombocytopenic purpura, blood disorders, bleeding disorders, hematologic disorders, hemostatic disorders, clotting disorders, hemostatic plug, prolonged bleeding time, petechiae, purpura, immune thrombocytopenic purpura, ITP, TTP, posttransfusion purpura, post-transfusion purpura, neonatal alloimmune thrombocytopenia, hemolytic uremic syndrome, HUS, von Willebrand disease, vWD, Bernard-Soulier syndrome, Glanzmann thrombasthenia, diffuse intravascular coagulation, DIC Please click here to view the full topic text: Platelet Disorders Background: The hemostatic system consists of platelets, coagulation factors, and the endothelial cells lining the blood vessels. The platelets arise from the cytoplasmic fragmentation of megakaryocytes in the bone marrow and circulate in blood as disc-shaped anucleate particles. Under normal circumstances, the resistance of the endothelial cell lining to interactions with platelets and coagulation factors prevents thrombosis. When endothelial continuity is disrupted and the underlying matrix is exposed, a coordinated series of events are set in motion to seal the defect (primary hemostasis). Platelets play a primary role in this process, interacting with subendothelium-bound von Willebrand factor (vWf) via the membrane glycoprotein Ib complex. This initial interaction (platelet adhesion) sets the stage for other adhesive reactions that allow the platelets to interact with each other to form an aggregate.

6. Virtual Hospital: University Of Iowa Family Practice Handbook, Fourth Edition: H Differentiation of platelet versus coagulation defects, presentation, bleeding caused by qualitative platelet disorders and many more topics. http://www.vh.org/adult/provider/familymedicine/FPHandbook/Chapter06/01-6.html

For Providers University of Iowa Family Practice Handbook, Fourth Edition, Chapter 6 Hematologic, Electrolyte, and Metabolic Disorders: Bleeding Disorders Ke Chen, MD, PhD and Mark A. Graber, MD Immediate Care Center, Iowa Health Physicians and Departments of Family Medicine and Emergency Medicine, University of Iowa College of Medicine Peer Review Status: Externally Peer Reviewed by Mosby Presentation Can often determine type of bleeding disorder by history and physical. Is there a family history of bleeding after minor surgical procedures, dental procedures, childbirth, or other trauma? Is this an isolated event, or has the patient had other bleeding episodes? Is the patient receiving medications that can cause a bleeding problem? Many drugs can contribute to bleeding, including semisynthetic penicillins, calcium channel blockers,cephalosporins, dipyridamole, thiazides, alcohol, quinidine, chlorpromazine, sulfonamides, INH, rifampin, methyldopa, phenytoin, barbiturates, warfarin, heparin, thrombolytic agents, NSAIDs and ASA, diuretics, allopurinol, TMP/SMX, and many others. Differentiation of Platelet versus Coagulation Defect Platelet defects Coagulation system defects . "Deep" bleeding (in the joint spaces, muscles, and retroperitoneal spaces) is common. Observed on exam as hematomas and hemarthroses.

7. THE MERCK MANUAL, Sec. 11, Ch. 133, Platelet Disorders Hematology And Oncology hyperlink to list of chapters in current section. Chapter133. platelet disorders. Topics. Hereditary Intrinsic platelet disorders. http://www.merck.com/pubs/mmanual/section11/chapter133/133c.htm

This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 11. Hematology And Oncology Chapter 133. Platelet Disorders Topics [General] Thrombocytopenia Platelet Dysfunction Platelet Dysfunction In some disorders, the platelets may be normal in number, yet hemostatic plugs do not form normally and the bleeding time will be long. Platelet dysfunction may stem from an intrinsic platelet defect or from an extrinsic factor that alters the function of otherwise normal platelets. Defects may be hereditary or acquired. Tests of the coagulation phase of hemostasis (eg, partial thromboplastin time and prothrombin time) are normal in most circumstances but not all (see Von Willebrand's Disease, below). HEREDITARY DISORDERS OF PLATELET FUNCTION When a patient's childhood history reveals easy bruising and bleeding after tooth extractions, tonsillectomy, or other surgical procedures, the finding of a normal platelet count but a prolonged bleeding time suggests a hereditary disorder affecting platelet function. The cause is either von Willebrand's disease, the most common hereditary hemorrhagic disease, or a hereditary intrinsic platelet disorder, which is much less common. Special studies (eg, measurement of von Willebrand antigen, platelet aggregation studies) establish the diagnosis, which is important because treatment differs. Whatever the cause of platelet dysfunction, drugs that may further impair platelet function should be avoidedparticularly aspirin and other NSAIDs used in arthritis. Acetaminophen may be used for analgesia because it does not inhibit platelet function.

8. Semple, John W. Associate Professor at the University of Toronto who researches platelet immunology. Summarises autoimmune platelet disorders. http://www.angelfire.com/ut/johnsnotes/

Updated Jan 5, 2003 John W. Semple's Laboratory Homepage Welcome. Let me introduce myself. I'm an Associate Professor at the University of Toronto and my lab is located at St. Michael's Hospital in Toronto, Canada. I'm currently a member of the Toronto Platelet Immunobiology Group (affectionately known as TPIG ). Its a network of scientists and physcians which are committed to transfusion immunology research. We are also active in disseminating information about immune blood cell disorders. The group has close links with the Hospital for Sick Children , and the Canadian Blood Services. The current members of my laboratory are: Ed Speck, Michael Kim, Ebrahim Sayeh, Malini Devi-Coopamah, Rukhsana Aslam, Kate Dyck, Maryam Ghaffar-Sedeh and Antonio Fabron Jr. Our research is in the area of platelet immunology. We primarily study the pathogenic immune mechanisms responsible for autoimmune (e.g. ITP or AITP) and alloimmune (e.g. transfusion-induced) platelet disorders and the mechanism of action of established therapies such as IVIg and anti-D. Related to these areas, we also attempt to develop novel and safe immunotherapeutic approaches to specifically down-regulate platelet antibodies. If we were to summarize the majority of the scientific literature regarding the immune pathogenesis of AITP, it would paint the following picture:

9. Platelet Disorders | Inherited Platelet Disorders INHE RITE D PLATELE T DISORDERS Thrombocytopenia (Low Platelet Numbers) Normally,the platelet count is regulated in a range of 150,000 400,000/per µl http://www.familygenetics.net/disorders/thrombocytopenia.htm

Inherited Thrombocytopenia Autosomal Dominant Sex-Linked Recessive ... Inherited Thrombocytosis I N H E R I T E D P L A T E L E T D I S O R D E R S Thrombocytopenia (Low Platelet Numbers) Normally, the platelet count is regulated in a range of 150,000 - 400,000/per µl. Platelet counts of 100,000 - 150,000 are considered borderline or moderate criteria for thrombocytopenia whereas counts less than 100,000/per µl are clearly abnormal. Symptoms do not usually develop until the platelet count is less than 50,000 , at which time easy bruising may be evident (even when there is minimal trauma) and tiny bruises (purple spots called petechiae) may appear on the skin. Surgeons would not perform routine surgery on a patient with less than 50,000 platelets, and the risk of prolonged bleeding after dental procedures or childbirth will be increased. Most commonly, low platelet counts are acquired after birth. Common causes include: pregnancy, chemotherapy or bone marrow transplantation, alcohol poisoning, aplastic anemia, leukemia, and myelodysplastic syndrome, all of which are caused by decreased numbers of megakaryocytes and decreased platelet production. Also, thrombocytopenia can result from rapid destruction of platelets from the blood, due to such diseases as Immune Thrombocytopenia Purpura (ITP), Disseminated Intravascular Coagulopathy (DIC), and Thrombotic Thrombocytopenia Purpura (TTP). Finally, platelets may be reduced in number as a consequence of an enlarged spleen, which can retain up to 1/3 of the total platelets. A bone marrow exam is usually done to examine the

10. THE MERCK MANUAL, Sec. 11, Ch. 133, Platelet Disorders Hematology And Oncology. Chapter 133. platelet disorders. Topics http://www.merck.com/pubs/mmanual/section11/chapter133/133b.htm

This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 11. Hematology And Oncology Chapter 133. Platelet Disorders Topics [General] Thrombocytopenia Platelet Dysfunction Thrombocytopenia Thrombocytopenia may stem from failed platelet production, splenic sequestration of platelets, increased platelet destruction or use, or dilution of platelets (see Table 133-1 ). Regardless of cause, severe thrombocytopenia results in a typical pattern of bleeding: multiple petechiae in the skin, often most evident on the lower legs; scattered small ecchymoses at sites of minor trauma; mucosal bleeding (epistaxis, bleeding in the GI and GU tracts, vaginal bleeding); and excessive bleeding after surgery. Heavy GI bleeding and bleeding into the CNS may be life threatening. However, thrombocytopenia does not cause massive bleeding into tissues (eg, deep visceral hematomas or hemarthroses), which is characteristic of bleeding secondary to coagulation disorders (eg, hemophiliasee Ch. 131 Diagnosis A thorough drug history must be taken to rule out exposure to drugs known to increase platelet destruction in sensitive patients. For example, up to 5% of patients receiving heparin may develop thrombocytopenia (see

11. Platelet Disorders | Types Of Inherited Thrombocytopenia thrombocytopenia. Platelet size is very small. Gray Platelet Syndrome Largeplatelets, decreased alpha granules, platelets count fluctuates. Bernard http://www.familygenetics.net/disorders/thrombocytopenia_types.htm

Inherited Thrombocytopenia Autosomal Dominant Sex-Linked Recessive ... Inherited Thrombocytosis T Y P E S O F I N H E R I T E D T H R O M B O C Y T O P E N I A Autosomal Dominant Can be passed from a single parent to child, equal risk for boys and girls. One in two chance of each child being affected. May-Hegglin Anomaly : Asymptomatic, giant platelets , white blood cell inclusions. Mutations of a non-muscle myosin gene on chromosome 22 ( ) have recently been identified as the cause of May-Hegglin Anomaly as well as the related Fechtner and Sebastian syndromes. (Kelley et al. Nature Genetics Alport Syndrome : Giant platelets associated with hearing loss and kidney problems, also caused by mutations of MYH9. Thrombocytopenia with normal size platelets : Linked to an unknown gene on chromosome 10 (Drachman et al. Blood 96(1): 118-125; Savoia et al. American Journal Of Human Genetics Paris-Trousseau thrombocytopenia : Small megakaryocytes Mediterranean Thrombocytopenia : Usually asymptomatic, frequently due to mutations in SPIb gene; when both copies of this gene are mutated the more severe Bernard Soulier Syndrome occurs (see below).

12. Platelet Disorders platelet disorders. Qualitative. Functional disorders (adhesion, aggregation,secretion); Very rare; Only once laboratory testing has http://www.uq.edu.au/vdu/HDUAnaemiaPlatelet.htm

Human Metapneumovirus Links Platelet Disorders Qualitative Functional disorders (adhesion, aggregation, secretion) Very rare Only once laboratory testing has eliminated all else do we settle for this Perform a blood smear from blood without an anticoagulant and look for clumping BT - normal reflects good function Perform platelet aggregation studies Bernard Soulier Syndrome Autosomal recessive, lifelong bleeding disorder Epistaxis, gastrointestinal tract bleeding, menorrhagia, easy bruising and excess bleeding following trauma Lack portions of the platelet membrane (eg GP Ib) which prevents interaction of platelets with vWF and subsequent adhesion to collagen Platelet count is normal to decreased BT is prolonged (relative to the slight decrease in platelets) Platelet aggregation test abnormal / Ristocetin abnormal HOME LINKS JOIN UP VIROLOGY ... KIDS STUFF

13. Parents Of Children With Platelet DisordersAbout Us Contact Us Publications Gues I N H E R I T E D P L A T E L E T D I S O R D E R S Thrombocytopenia (Low Platelet Numbers) Normally, the platelet count is regulated in a range of 150 000 400 000/per µl. Drachman Lab Platelet Biology platelet disorders Our Research http://www.pdsa.org/archive1c

14. Disorders Of Haemostasis bleeding, GIT haemorrhage, haematoma or delayed bleeding) from arteriole rupturerather than the more superficial bleeding with eg platelet disorders. http://www.uq.edu.au/vdu/HDUHaemostasisDis.htm

Human Metapneumovirus Links Disorders of Haemostasis Function of Haemostasis Prevention of blood loss from intact vessels Through the relationship between sound vessel walls and platelets Arrest of bleeding from damaged vessels Blood vessel reaction to injury Platelet plug formation at the site of damage Plasma proteins causing coagulation Components Of The Normal, Healthy Haemostatic Mechanism Vascular endothelium (vasoconstriction) Platelets (adhering and aggregating) Coagulation Factors (in the plasma which lead to coagulation) Fibrinolysis Inhibitors 1. Vascular Constriction Injury to the vascular wall leads to a local contractile response from smooth muscle cells induced by noradrenaline and serotonin. This mechanism is not sufficient to prevent blood loss, because vessels consists of capillaries which do not contain SMCs. Injury also leads to platelet released thromboxane A (a vasoconstrictor) Later, prostacyclin is released which counters the effects of thromboxane A

15. Inherited Platelet Disorders ! Inherited platelet disorders. This site is under construction! This page refers toinherited platelet disorders! Inherited disorders of the platelet membrane. http://www.akh-wien.ac.at/biomed-research/htx/inherit.htm

Inherited platelet disorders This site is under construction! If you are specialist in this field and you feel, we have made mistakes or you would like to contribute with your knowledge, please contact us via e-mail Introduction Platelets play a major role in haemostasis, and defects in platelet function may lead to bleeding. These defects may be inherited or acquired - the latter are far more common. Defective platelet function may present clinically with a variety of symptoms indicative of primary haemostatic failure, such as bruises, ecchymoses, epistaxis, gastrointestinal haemorrhage or menorrhagia. Platelet defects usually give rise to a fairly mild bleeding disorder, and patients may present with exzessive bleeding only after surgery. This page refers to inherited platelet disorders! Inherited disorders of the platelet membrane Glanzmann Thrombasthenia Thrombasthenia was first described by Glanzmann in 1918. It is an autosomal recessive defect of GPIIb/IIIa, a member of the Integrine family of cell surface receptors. Although most patients with this defect have no detectable platelet fibrinogen and absent clot retraction, platelets of some patients contain fibrinogen and can support clot retraction. These criteria were used to classify thrombasthenic patients as type I and II, respectively. Platelets of patients with type I have undetectable intact platelet GPIIb/IIIa complex, whereas in type II disease measureable amounts of functional GPIIb/IIIa can be detected. Clinical symptoms occur only in patients homozygous for thrombasthenia. The heterozygous condition appears to be asymptomatic, even though these subjects have only a half-normal concentration of GPIIb/IIIa

16. SmartEngine - SmartGuide ( DISEASE : Platelet Disorders ) All about DISEASE platelet disorders from SmartEngine.com Search For . DISEASE platelet disorders. Categories (1-3 of 3) http://disease.smartengine.com/shell/smartpage/Platelet_Disorders

SmartGuide Web Auctions DISEASE : Platelet Disorders Categories (1-2 of 2) Health: Conditions_and_Diseases: Blood_Disorders: Platelet Science: Biology: Immunology: People Web Pages Acquired Bleeding Disorders An article by Thomas G. DeLoughery, Associate Professor of Medicine. Platelet transfusion therapy and dysfunctional platelets are discussed. - http://www.ohsu.edu/som-hemonc/handouts/deloughery/bleed.shtml Health: Conditions and Diseases: Blood Disorders: Platelet Semple, John W. Associate Professor at the University of Toronto who researches platelet immunology. Summarises autoimmune platelet disorders. - http://www.angelfire.com/ut/johnsnotes/ Science: Biology: Immunology: People Virtual Hospital: Bleeding Disorders Differentiation of platelet versus coagulation defects, presentation, bleeding caused by qualitative platelet disorders and many more topics. - http://www.vh.org/adult/provider/familymedicine/FPHandbook/Chapter06/01-6.html Health: Conditions and Diseases: Blood Disorders: Platelet About Us Contact Us Our Partners ... Help

17. UMHS - Qualitative Platelet Disorders Hemophilia and Coagulation Disorders Qualitative platelet disorders. Whatare platelets? Platelets How are platelet disorders diagnosed? The http://www.med.umich.edu/1libr/topics/hemo05.htm

Other Health Topics Health Topics A-Z Hemophilia and Coagulation Disorders Qualitative Platelet Disorders What are platelets? Platelets are small disc shaped cells that are formed in the bone marrow. Seventy to eighty percent of platelets circulate in the bloodstream while the remainders are stored in the spleen. The average platelet lives about 10 days. Platelets play a crucial role in helping blood to clot. The primary functions of platelets are adhesion, aggregation, activation and secretion (Table I). A defect in any one of these functions will result in an increased tendency to bleed. Table I Platelet Functions Platelet adhesion occurs when there is an injury to a blood vessel. Platelets attach to the lining of the injured blood vessel and begin the first phase of the clotting process. After platelets initially begin to adhere to the wall of an injured blood vessel, additional platelets are called to the site of injury. The platelets begin to aggregate or stick to each other, forming a platelet plug. Granules inside the platelets function to store and release specific proteins that help platelets aggregate at the site of blood vessel injury.

18. Platelet Disorders You can download this Powerpoint presentationby clicking here. Back to Bibliography. http://www.biocytex.fr/biblio/com/disorder/pltdisord.htm

You can download this Powerpoint presentation by clicking here. Back to Bibliography

19. Parents Of Children With Platelet Disorders Discussion Parents of Children with platelet disorders. Contents Search Post Welcome! The purpose of this discussion group http://www.pdsa.org/Childdiscgroup/

About Us Contact Us Publications Guest Book ... Newsletters Discussion - Parents of Children with Platelet Disorders Contents Search Post Welcome! The purpose of this discussion group is to foster supportive dialog about the subject of ITP and other platelet disorders. Please follow the Netiquette Guidelines The views expressed on the discussion area and resultant communications are those of the contributors and not necessarily the views of PDSA. We assume no responsibility for any actions taken as a result of this information. For advice on your unique medical condition, please consult your health care professional. New to ITP? Read our FAQ Pregnant? Go to our pregnancy site See prior discussion group posts in our archives. Come to our ITP Conference 2003 - June 20-22, Rosemont, IL CONTENTS Note: you may need to reload this page to see the most recent additions. Elaine - Jacob's mom (3) Susan - Zach's mom (3) 30 Mar 2003 follow up Susan 30 Mar 2003 Hey, I know the test you are talking about.....

20. Dr. Rose's Peripheral Brain--PLATELET DISORDERS platelet disorders. Causes of Thrombocytopenia. Idiopathic ThrombocytopenicPurpura. Thrombotic Thrombocytopenic Purpura Platelet lifetime avg. http://faculty.washington.edu/momus/PB/platelet.htm

PLATELET DISORDERS Causes of Thrombocytopenia Idiopathic Thrombocytopenic Purpura Thrombotic Thrombocytopenic Purpura Platelet lifetime avg. 7d Normal platelet count = 150-400k/uL Common wisdom has it that initial bleeding due to platelet disorders is usually from mucous membranes rather than bruising of the skin or hemarthrosis

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