Laboratory assessment of platelet function and coagulation

2008 ◽  
pp. 19-31
Author(s):  
Alan Michelson ◽  
Andrew Frelinger III ◽  
Jeffrey Weitz
Keyword(s):  
Platelet Function ◽  
Laboratory Assessment

Assessment of Menorrhagia in Females Followed for Bleeding Disorders at the Hemophilia Center of Western New York-Correlation between Clinical Presentation and Laboratory Parameters.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3984-3984
Author(s):  
Eric E. Bush ◽  
James Kepner ◽  
Shannon Smiley ◽  
Linda Belling ◽  
Zale P. Bernstein
Keyword(s):  
New York ◽  
Menstrual Cycle ◽  
Platelet Function ◽  
Clinical Presentation ◽  
P Value ◽  
Point System ◽  
Laboratory Assessment ◽  
Self Assessment ◽  
Von Willebrand’S Factor ◽  
The Relationship

Abstract Menorrhagia is a common problem among women. The cause of which, in some individuals, has been attributed to von Willebrand’s disease. The assessment of this condition has been hampered by the lack of easily available and consistent laboratory assessment of levels of this factor that correlate with the patient’s clinical presentation. Therefore we initiated a study to correlate the patient’s self assessment of their menorrhagia with their levels of von Willebrand’s factor (VWF) and platelet function. A peripheral blood assessment chart (PBAC) was utilized for patient self-assessment of blood loss during their menstrual cycle. The PBAC is a validated, well-established method which utilized a point system that quantifies the number and extent of soiling of tampons and pads used during a patient’s menstrual cycle. The PFA-100 has been used as an adjunct for lab assessment of platelet function. This is a high shear-inducing device which simulates primary hemostasis after injury to small vessel. This apparatus consists of a reservoir for whole blood and a small capillary surmounted by a collagen-coated membrane with a central aperture. Platelet agonist which is either epinephrine or ADP is present on the membrane. Closure time is reported as a variable which inversely corresponds with von Willebrand factor levels (or platelet function). Clinical correlation with its results are needed. In addition, blood samples were analyzed for Von Willebrand’s factor antigen (VWFA) and Ristocetin co-factor activity (RCOA) using a CLIA approved laboratory. We explored the relationship between PBAC, PFA-100 and VWFA and RCOA levels. Twenty-six patients were enrolled after obtaining an institutional board approved informed consent. Pearson association estimates and P values to assess the association between one month PBAC scores and PFA-100 showed 0.463 (with a p-value of 0.017). A similar analysis between one month PBAC scores and VWFA and RCOA showed 0.099 (p=0.632) and the association between PFA-100 and VWFA and RCOA showed an inverse relationship of −0.481 (p=0.013). These results confirm a correlation between VWFA and RCOA and assessment of platelet function utilizing a PFA-100. Furthermore, there was a correlation between PBAC scores and the results of the PFA-100. The association between PBAC scores and VWAF screening levels did not show significance. These results suggest further data are necessary to understand the relationship between these variables and further suggests that the PFA-100 may offer a more sensitive assessment of platelet function that correlates with clinical presentation than levels of VWFA or RCOA.

Evaluation of platelet dense granules for determining storage pool deficiencies by HVEM image and quantitative analysis

1996 ◽  
Vol 54 ◽  
pp. 770-771
Author(s):  
W.T. Gunning ◽  
J.N. Turner ◽  
K. Buttle ◽  
E.P. Calomeni ◽  
N.A. Lachant ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Platelet Function ◽  
Electron Microscopic ◽  
Von Willebrand's Disease ◽  
Dense Granules ◽  
Storage Pool ◽  
Prolonged Bleeding ◽  
Microscopic Evaluation ◽  
Storage Pools ◽  
Electron Lucent

There are a variety of conditions which have been associated with prolonged bleeding times. If other etiologies including von Willebrand's disease have been ruled out, a platelet function disorder must be considered. The best, if not only, technique to make this diagnosis is the electron microscopic evaluation of whole air dried platelets. Bull first described the presence of dense granules in whole platelets in 1968 and the technique has been utilized extensively The electron dense or delta granules are easily distinguished from the larger more numerous alpha granules which are electron lucent. The significance of the dense granules is that they are known to be “storage pools” of serotonin, calcium, adenosine di- and triphosphate, and pyrophosphate. Prolonged bleeding times may be directly related to an insufficiency of these substances. The diagnosis of a storage pool deficiency is made when either the storage content of the dense granules is abnormal or their number is diminished. We observe normal platelets to have 4-6 dense granules, which agrees with the literature.

Uremic toxins and platelet function

1970 ◽  
Vol 126 (5) ◽  
pp. 823-826 ◽  
Author(s):  
H. I. Horowitz
Keyword(s):  
Platelet Function ◽  
Uremic Toxins

“Aspirin - resistance”? A few critical considerations on definition, terminology, diagnosis, clinical value, natural course of atherosclerotic disease, and therapeutic consequences

VASA ◽  
2011 ◽  
Vol 40 (6) ◽  
pp. 429-438 ◽  
Author(s):  
Berent ◽  
Sinzinger
Keyword(s):  
Platelet Function ◽  
Point Of Care ◽  
Aspirin Resistance ◽  
Point Of View ◽  
Evidence Based ◽  
Platelet Function Tests ◽  
Clinical Value ◽  
Vascular Events ◽  
Therapeutic Consequences ◽  
Function Tests

Based upon various platelet function tests and the fact that patients experience vascular events despite taking acetylsalicylic acid (ASA or aspirin), it has been suggested that patients may become resistant to the action of this pharmacological compound. However, the term “aspirin resistance” was created almost two decades ago but is still not defined. Platelet function tests are not standardized, providing conflicting information and cut-off values are arbitrarily set. Intertest comparison reveals low agreement. Even point of care tests have been introduced before appropriate validation. Inflammation may activate platelets, co-medication(s) may interfere significantly with aspirin action on platelets. Platelet function and Cox-inhibition are only some of the effects of aspirin on haemostatic regulation. One single test is not reliable to identify an altered response. Therefore, it may be more appropriate to speak about “treatment failure” to aspirin therapy than using the term “aspirin resistance”. There is no evidence based justification from either the laboratory or the clinical point of view for platelet function testing in patients taking aspirin as well as from an economic standpoint. Until evidence based data from controlled studies will be available the term “aspirin resistance” should not be further used. A more robust monitoring of factors resulting in cardiovascular events such as inflammation is recommended.

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