II. Definitions

  1. Platelet
    1. Irregular, small ( 3um) disc shaped fragments, pieces of Megakaryocytes in the Bone Marrow
    2. Key component of Blood Clotting

III. Physiology

  1. Platelets are generated in the Bone Marrow at a rate of 10% of total Platelet Count per day
  2. Aggregate at damaged blood vessels to form clot
    1. Cross-bridged to the vessel wall via the glycoprotein, Von Willebrand Factor
  3. Contain actin and myosin (found in muscle fibers)
    1. Allow Platelets to contract and close a vessel wall opening
  4. Promote Clot Formation
    1. Attract additional Platelets by secreting chemoattractants (ADP, Thromboxane A2)
    2. Produce Fibrin stabilizing factor (binds Fibrin into mesh)
    3. Platelet factor 3 (PF3) and phospholipids, contained in the Platelet membrane, promote Clot Formation
  5. Release vasoactive mediators (arachidonic acid metabolites, biogenic amines) - especially Vasoconstrictors
    1. Thromboxane A2
      1. Thromboxane A2 activates Platelets, increasing their "stickiness" in Clot Formation
      2. Thromboxane A2 production is dependent on the enzyme cyclooxygenase
    2. PGF2 alpha
    3. Serotonin (5-HT)
  6. Other functionality
    1. Phagocytosis of Antigen-Antibody complexes
  7. Inhibitors of Platelet aggregation and stickiness
    1. Aspirin
      1. Inhibits cyclooxygenase, reducing Thromboxane A2 levels and Clot Formation
    2. Platelet ADP Receptor Antagonist (e.g. Clopidogrel, Prasugrel, Ticagrelor)
      1. Inhibit ADP binding to Platelets and Platelet aggregation
    3. Glycoprotein IIB/IIIA Inhibitor (e.g. Abciximab, Tirofiban, Eptifibatide)
      1. Inhibit Fibrinogen and Von Willebrand Factor binding to activated Platelet Glycoprotein IIB/IIIA receptors
      2. Inhibits Platelet aggregation, by inhibiting Platelet binding to one another
    4. Dipyridamole
      1. Platelet Phosphodiesterase Inhibitor (PDE3 inhibitor)
      2. PDE3 would normally breakdown cAMP (Cyclic Adenosine monophosphate)
      3. Excess CAMP buildup inhibits Platelet aggregation (and also results in vasodilation)
  8. Measures of Platelet function
    1. Platelet Function Closure Time
    2. Bleeding Time

IV. Labs: Platelet Count Normal Range

  1. Newborns
    1. Preterm: 100,000 to 300,000 per mm3
    2. Term: 140,000 to 300,000 per mm3
  2. Infant: 200,000 to 475,000 per mm3
  3. Child: 150,000 to 450,000 per mm3
  4. Adults: 150,000 to 400,000/mm3

V. Interpretation: Increased Platelet Count

VI. Interpretation: Decreased Platelet Count

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Related Studies

Ontology: Blood Platelet Disorders (C0005818)

Definition (MSHCZE) Porucha funkce trombocytů, která má obvykle za následek zvýšenou krvácivost. K dědičným poruchám patří např. Bernardův-Soulierův syndrom, Glanzmannova trombastenie, syndrom Heřmanského-Pudlákův aj. Druhotně je funkce destiček (adheze) narušena u Willebrandovy nemoci. Dále může být součástí krevních chorob (funkčně nedostatečné jsou destičky i u primární trombocytemie) i onemocnění jiných orgánů, např. ledvin či jater. Funkci krevních destiček narušují i některé léky, čehož se využívá k antiagregační léčbě. Podstatou trombocytopatie mohou být defekty povrchových glykoproteinů, inhibice enzymů (cyklooxygenázy, fosfolipázy C), nedostatečná produkce látek z destiček uvolňovaných aj. (cit. Velký lékařský slovník online, 2012 http://lekarske.slovniky.cz/ )
Definition (MEDLINEPLUS)

Platelets are little pieces of blood cells. Platelets help wounds heal and prevent bleeding by forming blood clots. Your bone marrow makes platelets. Problems can result from having too few or too many platelets, or from platelets that do not work properly.

If your blood has a low number of platelets, you can be at risk for mild to serious bleeding. If your blood has too many platelets, you may have a higher risk of blood clots. With other platelet disorders, the platelets do not work as they should. For example, in von Willebrand Disease, the platelets cannot stick together or cannot attach to blood vessel walls. This can cause excessive bleeding.

Treatment of platelet disorders depends on the cause.

NIH: National Heart, Lung, and Blood Institute

Definition (MSH) Disorders caused by abnormalities in platelet count or function.
Definition (CSP) qualitative disorder of the blood platelets, due mainly to deficiency of platelet factor 3.
Definition (CSP) disorders caused by abnormalities in platelet count or function.
Concepts Disease or Syndrome (T047)
MSH D001791
SnomedCT 22716005
English Blood Platelet Disorder, Disorder, Blood Platelet, Disorders, Blood Platelet, Platelet Disorder, Blood, Platelet Disorders, Blood, Thrombocytopathies, Thrombocytopathy, platelet disorder, Blood Platelet Disorders, BLOOD PLATELET DIS, thrombocytopathy, thrombocytopathy (diagnosis), Disorder platelet, Platelet disorders, Blood Platelet Disorders [Disease/Finding], platelet blood disorder, thrombocytopathies, blood platelet disorder, disorders platelets, blood platelet disorders, thrombocyte disorders, blood disorder platelet, platelet disorders, disorder platelet, Platelet Disorders, Thrombocyte disorders, Abnormal platelets present, Blood platelet disorders, Platelet disorder, Platelet disorder (disorder), Platelet disorder, NOS, Thrombocytopathy, NOS
Italian Alterazioni piastriniche, Patologia piastrinica, Alterazione delle piastrine, Trombocitopatia, Disordini delle piastrine
Dutch trombocytopathie, bloedplaatjesaandoening, plaatjesaandoeningen, Bloedplaatjesstoornis, Trombocytopathie
French Trouble plaquettaire, Thrombocytopathie, Trouble des plaquettes, Anomalies des plaquettes, Anomalies plaquettaires, Thrombocytopathies, Thrombopathies, Troubles des plaquettes, Troubles plaquettaires
German Thrombozytopathie, Thrombozytenerkrankung, Erkrankungen der Thrombozyten, Thrombozytenstoerung, Thrombozytenkrankheiten, Trombozytopathie
Spanish Trastorno de las plaquetas, trastorno de las plaquetas (trastorno), trastorno de las plaquetas, trombocitopatía, Trastornos plaquetarios, Trastorno plaquetario, Trastornos de las Plaquetas Sanguíneas, Trombocitopatía
Japanese 血小板障害, ケッショウバンショウ, ケッショウバンショウガイ, 血小板異常, 血小板症
Swedish Blodplättssjukdomar
Finnish Verihiutaleiden toimintahäiriöt
Russian TROMBOTSITOPATIIA, TROMBOTSITOV NARUSHENIIA, ТРОМБОЦИТОВ НАРУШЕНИЯ, ТРОМБОЦИТОПАТИЯ
Czech Trombocytopatie, Poruchy krevních destiček, Porucha krevních destiček, Porucha funkce krevních destiček, trombocytopathie, trombocyty - poruchy, trombocytopatie, poruchy trombocytů
Croatian TROMBOCITI, POREMEĆAJI, KRVNE PLOČICE, POREMEĆAJI, TROMBOCITOPATIJA
Polish Skazy krwotoczne płytkowe, Nieprawidłowości płytek krwi, Choroby komórek płytkowych
Hungarian thrombocyta-betegség, Thrombocytopathia, thrombocyta betegség, Thrombocyta betegségek
Norwegian Blodplatedefekter, Trombocytopati, Blodplateforstyrrelser, Trombopati
Portuguese Afecções plaquetárias, Anomalia das plaquetas, Transtornos Plaquetários, Trombocitopatia

Ontology: Blood Platelets (C0005821)

Definition (MSHCZE) Krevní destička. Drobné tělísko bez jádra vznikající z megakaryocytu, v krvi přežívá zhruba 8–10 dnů. Trombocyty se uplatňují při hemostáze, jednak v časné fázi při tvorbě tzv. destičkového trombu, jednak ovlivněním koagulace (destičkové fosfolipidy). (cit. Velký lékařský slovník online, 2013 http://lekarske.slovniky.cz/ )
Definition (NCI_CDISC) An irregular, disc-shaped structure in the blood that assists in blood clotting. Platelets are not blood cells, they are fragments of large bone marrow cells called megakaryocytes. (NCI)
Definition (NCI) An irregular, disc-shaped element in the blood that assists in blood clotting. Platelets are not blood cells, they are fragments of large bone marrow cells called megakaryocytes.
Definition (NCI_NCI-GLOSS) A tiny piece of a cell found in the blood that breaks off from a large cell found in the bone marrow. Platelets help wounds heal and prevent bleeding by forming blood clots.
Definition (MSH) Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.
Definition (CSP) non-nucleated disk shaped cells formed in the megakaryocyte and found in the blood of all mammals; they are mainly involved in blood coagulation, and have a role in inflammation.
Concepts Cell (T025)
MSH D001792
SnomedCT 256396005, 259727009, 16378004
LNC LP70360-0, LP7631-7, LP16772-3, LP14597-6, MTHU002432, MTHU008063
English Platelet, Blood, Platelets, Platelets, Blood, Thrombocytes, Blood Platelet, Bizzozero's corpuscle/cell, Deetjeen's body, Hayem's elementary corpuscle, Blood platelet, platelets blood, blood platelet, platelets, plt platelet, blood platelets, platelet blood, thrombocytes, Platelet (body structure), Thrombocyte (platelet), Blood platelets, platelet, thrombocyte, PLATELET, Thrombocyte, Platelet, PLT - Platelet, PLT - Platelets, Platelet (cell structure), Platelet [dup] (body structure), Blood Platelets, Platelets (Blood), Reticuloendothelial System, Platelets
French Thrombocyte, Plaquettes, Plaquettes sanguines, Thrombocytes
Swedish Blodplättar
Czech trombocyty, krevní destičky
Finnish Verihiutaleet
Italian Trombociti, Piastrine
Russian KROVIANYE PLASTINKI, PLASTINKI, TROMBOTSITY, КРОВЯНЫЕ ПЛАСТИНКИ, ПЛАСТИНКИ, ТРОМБОЦИТЫ
Japanese 血小板, 栓球
Croatian TROMBOCITI
Latvian Asins plātnītes, Trombocīti, Plātnītes
Polish Komórki płytkowe, Płytki krwi
Norwegian Blodplater, Trombocytter
Spanish trombocitos, plaqueta [dup] (estructura corporal), plaqueta (estructura celular), plaqueta (estructura corporal), plaqueta, trombocito, Plaquetas, Trombocitos
German Thrombocyten, Thrombozyten, Blutplättchen
Dutch Bloedplaatje, Bloedplaatjes, Trombocyt, Trombocyten
Portuguese Plaquetas, Trombócitos

Ontology: Platelet Count measurement (C0032181)

Definition (NCI) The determination of the number of platelets in a blood sample, usually expressed as platelets per cubic millimeter (cmm) of whole blood.
Definition (NCI_CDISC) A measurement of the platelets (non-nucleated thrombocytes) in a biological specimen.
Definition (MSH) The number of PLATELETS per unit volume in a sample of venous BLOOD.
Concepts Laboratory Procedure (T059)
MSH D010976
SnomedCT 142973006, 165560004, 142967005, 61928009
English Blood Platelet Count, Blood Platelet Counts, Blood Platelet Number, Blood Platelet Numbers, Count, Blood Platelet, Count, Platelet, Counts, Blood Platelet, Counts, Platelet, Number, Blood Platelet, Number, Platelet, Numbers, Blood Platelet, Numbers, Platelet, Platelet Count, Platelet Count, Blood, Platelet Counts, Platelet Counts, Blood, Platelet Number, Platelet Number, Blood, Platelet Numbers, Platelet Numbers, Blood, Platelet count NOS, Thrombocyte count, platelet count, platelets, platelet count (lab test), blood platelet numbers, blood platelet count, platelets count, thrombocyte count, platelet number, platelet counts, blood platelet counts, Platelet count NOS (procedure), PLAT, Anucleated Thrombocytes, Platelets, Whole Blood Platelet Counts, Platelet count, Plt - Platelet count, Platelet count (procedure), Platelet count - observation, Platelet Count measurement
Italian Conta delle piastrine, Numero delle piastrine, Numero delle piastrine del sangue, Conta piastrinica del sangue, Conta piastrinica
Dutch trombocytentelling, plaatjestelling, Bloedplaatjestelling, Telling, trombocyten-, Trombocytengetal (Plaatjesgetal), Trombocytentelling (Bloedplaatjestelling)
French Numération des thrombocytes, Numération des plaquettes sanguines, Numération plaquettaire, Numération des plaquettes, Taux de plaquettes, Taux de plaquettes sanguines
Portuguese Número de trombócitos, Número de plaquetas, Contagem de Plaquetas, Contagem de Plaquetas Sanguíneas, Número de Plaquetas, Número de Plaquetas Sanguíneas
Spanish Recuento de trombocitos, recuento de plaquetas, SAI, Platelet count NOS, recuento de plaquetas, SAI (procedimiento), recuento de plaquetas (procedimiento), recuento de plaquetas, Recuento de plaquetas, Recuento de Plaquetas, Número de Plaquetas Sanguíneas, Número de Plaquetas, Recuento de Plaquetas Sanguíneas
Swedish Trombocytantal
Japanese ケッショウバンスウ, 血小板計算, 血小板計数, 血小板数, 血小板算定法
Czech trombocyty - počet, Počet trombocytů
Finnish Verihiutalemäärä
Russian TROMBOTSITOV PODSCHET, TROMBOTSITOV KOLICHESTVO, ТРОМБОЦИТОВ КОЛИЧЕСТВО, ТРОМБОЦИТОВ ПОДСЧЕТ
Polish Liczba płytek krwi, Liczba komórek płytkowych
Hungarian Thrombocyta szám
Norwegian Blodplateantall, Blodplatetelling, Trombocytt-telling
German Thrombozytenzahl, Blutplättchenzählung, Thrombozytenzählung