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ID naloge: 153 Letnik: 2003 Predmet: interna medicina
OCENA TROMBOCITNE FUNKCIJE Z ZAPIRALNIM CASOM PRI ZDRAVIH OSEBAH, BOLNIKIH S POLICITEMIJO RUBRO VERO IN ESENCIALNO TROMBOCITEMIJO
Avtor: Rika Strauch
Mentor: doc. dr. Uroš Mlakar
Somentor: asist. mag. Irena Preložnik Zupan
IZHODIŠCE: Med kronicne nelevkemicne mieloproliferativne bolezni (KNMB) sodijo prava policitemija (PRV, policitemija rubra vera), esencialna trombocitemija (ET) in kronicna idiopatska mielofibroza (KIM). To so klonske bolezni, za katere je znacilno postopno povecanje števila eritrocitov, granulocitov in trombocitov. Za PRV in ET so znacilni pogosti tromboticni zapleti in krvavitve. Vzrok za te zaplete je okvarjena funkcija trombocitov, pri PRV pa je za te zaplete odgovorna tudi povecana viskoznost krvi zaradi povecane mase eritrocitov v krvnem obtoku.
Do nedavnega so oceno trombocitne funkcije ugotavljali s casom krvavitve (CK) in agregometrijo, vendar se je prva preiskava izkazala za neuporabno zaradi majhne obcutljivosti, druga pa za presejalno preiskavo ni primerna zaradi svoje zamudnosti in zapletenosti. V zadnjem casu se je uveljavilo tudi ugotavljanje trombocitne funkcije z zapiralnim casom (ZC) na analizatorju PFA-100®. Ta nacin ugotavljanja funkcije trombocitov bi lahko uporabili tudi kot presejalno preiskavo pri mieloproliferativnih boleznih. Podatki o pomenu te preiskave pri kronicnih nelevkemicnih mieloproliferativnih boleznih so v literaturi redki.
NAMEN: Z našo raziskavo želimo ugotoviti:
1. normalne vrednosti ZC pri zdravih osebah za hematološki laboratorij Klinicnega oddelka (KO) za hematologijo Klinicnega centra.
2. delež bolnikov s PRV in ET z okvarjeno trombocitno funkcijo, ocenjeno z ZC na PFA-100®.
HIPOTEZA: Predvidevamo, da ima okvarjeno trombocitno funkcijo znaten delež bolnikov s PRV in ET. Namesto CK, ki zaradi slabe obcutljivosti ni primerna presejalna preiskava za oceno trombocitne funkcije, bi trombocitno funkcijo lahko ocenjevali z ZC.
METODE: V raziskavi, s katero smo dolocili normalne vrednosti ZC, je sodelovalo 120 zdravih preiskovancev, ki v svoji anamnezi niso imeli podatka o motnjah hemostaze ali uživanju zdravil, ki vplivajo na funkcijo trombocitov. Vrednost ocene trombocitne funkcije pri PRV in ET smo analizirali pri 54 bolnikih (29 s PRV in 25 z ET), ki se zdravijo na KO za hematologijo. Preiskovancem smo dolocili krvno sliko in zapiralni cas. Zapiralni cas smo dolocili z dvema testnima celicama. Prva vsebuje agonista agregacije kolagen in adrenalin (CEPI), druga pa kolagen in ADP (CADP). Vzorce krvi za dolocanje zapiralnega casa smo odvzeli v epruveto z 0,105M natrijevim citratom. Preiskavo smo opravili znotraj štirih ur po odvzemu. Pri 20 zdravih preiskovancih in 27 bolnikih s PRV smo izmerili tudi cas krvavitve po Ivy-ju.
REZULTATI IN ZAKLJUCKI: Za zapiralni cas, merjen s testno celico CEPI, je obmocje normalnih vrednosti od 82 s do 157 s, za zapiralni cas, merjen s testno celico CADP, pa od 65 do 119 s. Pri zdravih osebah kajenje in oralni kontraceptivi niso vplivali na zapiralna casa CEPI in CADP. Vpliv spola in VSE (volumen stisnjenih eritrocitov) na zapiralni cas CEPI nismo ugotovili. Ugotovili smo statisticno pomembno povezavo zapiralnega casa CADP z VSE in spolom, vendar je ta vpliv na zapiralni cas CADP verjetno klinicno nepomemben.
Pri bolnikih s PRV in ET je bil zapiralni cas CEPI podaljšan v 51%, zapiralni cas CADP pa v 18%. Delež bolnikov s podaljšanim ZC CEPI je bil v podskupini s PRV nekoliko vecji kot pri ET. Podskupini PRV in ET se glede deleža bolnikov s podaljšanim ZC CADP med seboj nista razlikovali.
Sklepamo, da je merjenje zapiralnega casa s testno celico CEPI primeren presejalni test za ugotavljanje motnje trombocitne funkcije pri bolnikih s kronicno nelevkemicno mieloproliferativno boleznijo. Dodatna meritev zapiralnega casa s testno celico CADP ne poveca obcutljivosti preiskave.
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[Abstract / English version]
OCENA TROMBOCITNE FUNKCIJE Z ZAPIRALNIM CASOM PRI ZDRAVIH OSEBAH, BOLNIKIH S POLICITEMIJO RUBRO VERO IN ESENCIALNO TROMBOCITEMIJO
Author: Rika Strauch
Mentor: doc. dr. Uroš Mlakar
Co-mentor: asist. mag. Irena Preložnik Zupan
BACKGROUND: Polycythaemia vera (PV) is a clonal myeloproliferative disease characterised by increased red blood cell numbers. Essential thrombocythaemia (ET) is another clonal myeloproliferative disease, but is characterised by sustained thrombocytosis in the blood and increased number of large, mature megakaryocytes in the bone marrow. Episodes of thrombosis and haemorrhage, which they both have in common, are due to platelet dysfunction, and especially in PV, higher viscosity of the blood due to elevated red blood cell mass.
Simplate® bleeding time (BT) was the only screening test for platelet function for quite a long time, along with aggregometry, although neither proved as a valuable screening method for that purpose. Recently, a new method for evaluation of platelet dysfunction was introduced: closure time (CT) measured using the PFA-100®. With this method, platelet dysfunction in myeloproliferative disorders, such as PV or ET, could be evaluated. There is not much data on the subject of altered platelet function in myeloproliferative diseases and PFA-100®.
AIM: To establish our own reference ranges for haematology laboratory at the Department of Haematology in Clinical Center in Ljubljana. Our aim was to determine the percentage of PV and ET patients with disturbed platelet function, measured using the PFA-100®.
HYPOTHESIS: We assume that majority of PV and ET patients have dysfunctional platelets, measured with PFA-100®. We believe that instead of BT we could use CT as a screening test for platelet dysfunction.
METHODS: Written informed consent was obtained from 120 healthy volunteers without any history of hemorrhagic diathesis. They were all enrolled in our study to determine reference range for our laboratory. 54 patients (29 with PV, 25 with ET) were also enrolled in our study to determine platelet function with PFA-100®. Platelet count and hematocrite were preformed with a Coulter STKS cell counter (Coulter electronics, Miami, USA). Citrated whole blood was used for measuring the CT. We used two test cartridges: one with collagen and epinephrine (CEPI) which was used first, and the second with collagen and ADP (CADP). Blood samples were processed in four hours. 20 healthy persons and 27 PV patients had their BT done.
RESULTS AND CONCLUSIONS: Reference range for CEPI was 82 - 157 s, for CADP 65 - 119 s. Smoking and oral contraceptives showed no correlation with CEPI or CADP. There was no correlation between gender and CEPI nor hematocrite and CEPI, but we noticed a correlation between parameters mentioned above and CADP, although this difference is probably clinically non-significant. 51% of PV and ET patients had CEPI above upper range, but only 18% with CADP. We concluded that PFA-100® is a suitable screening test for platelet dysfunction in patients with myeloproliferative disorder. Additional testing with CADP does not improve the number of cases with altered platelet function found with CEPI.
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