Laboratory examination used to monitor and evaluate platelet function in a patient's blood.

The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.

Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.

Drugs or agents which antagonize or impair any mechanism leading to blood platelet aggregation, whether during the phases of activation and shape change or following the dense-granule release reaction and stimulation of the prostaglandin-thromboxane system.

The prototypical analgesic used in the treatment of mild to moderate pain. It has anti-inflammatory and antipyretic properties and acts as an inhibitor of cyclooxygenase which results in the inhibition of the biosynthesis of prostaglandins. Aspirin also inhibits platelet aggregation and is used in the prevention of arterial and venous thrombosis. (From Martindale, The Extra Pharmacopoeia, 30th ed, p5)

An effective inhibitor of platelet aggregation commonly used in the placement of STENTS in CORONARY ARTERIES.

The process whereby PLATELETS adhere to something other than platelets, e.g., COLLAGEN; BASEMENT MEMBRANE; MICROFIBRILS; or other "foreign" surfaces.

The number of PLATELETS per unit volume in a sample of venous BLOOD.

Blood tests that are used to evaluate how well a patient's liver is working and also to help diagnose liver conditions.

Duration of blood flow after skin puncture. This test is used as a measure of capillary and platelet function.

A series of progressive, overlapping events, triggered by exposure of the PLATELETS to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable hemostatic plug.

Measurement of the various processes involved in the act of respiration: inspiration, expiration, oxygen and carbon dioxide exchange, lung volume and compliance, etc.

Surface glycoproteins on platelets which have a key role in hemostasis and thrombosis such as platelet adhesion and aggregation. Many of these are receptors.

Disorders caused by abnormalities in platelet count or function.

Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.

Platelet membrane glycoprotein complex important for platelet adhesion and aggregation. It is an integrin complex containing INTEGRIN ALPHAIIB and INTEGRIN BETA3 which recognizes the arginine-glycine-aspartic acid (RGD) sequence present on several adhesive proteins. As such, it is a receptor for FIBRINOGEN; VON WILLEBRAND FACTOR; FIBRONECTIN; VITRONECTIN; and THROMBOSPONDINS. A deficiency of GPIIb-IIIa results in GLANZMANN THROMBASTHENIA.

A CXC chemokine that is found in the alpha granules of PLATELETS. The protein has a molecular size of 7800 kDa and can occur as a monomer, a dimer or a tetramer depending upon its concentration in solution. Platelet factor 4 has a high affinity for HEPARIN and is often found complexed with GLYCOPROTEINS such as PROTEIN C.

A stable, physiologically active compound formed in vivo from the prostaglandin endoperoxides. It is important in the platelet-release reaction (release of ADP and serotonin).

A platelet-specific protein which is released when platelets aggregate. Elevated plasma levels have been reported after deep venous thrombosis, pre-eclampsia, myocardial infarction with mural thrombosis, and myeloproliferative disorders. Measurement of beta-thromboglobulin in biological fluids by radioimmunoassay is used for the diagnosis and assessment of progress of thromboembolic disorders.

An enzyme formed from PROTHROMBIN that converts FIBRINOGEN to FIBRIN.

Blood tests used to evaluate the functioning of the thyroid gland.

The transfer of blood platelets from a donor to a recipient or reinfusion to the donor.

The process which spontaneously arrests the flow of BLOOD from vessels carrying blood under pressure. It is accomplished by contraction of the vessels, adhesion and aggregation of formed blood elements (eg. ERYTHROCYTE AGGREGATION), and the process of BLOOD COAGULATION.

A phospholipid from the platelet membrane that contributes to the blood clotting cascade by forming a phospholipid-protein complex (THROMBOPLASTIN) which serves as a cofactor with FACTOR VIIA to activate FACTOR X in the extrinsic pathway of BLOOD COAGULATION.

Formation and development of a thrombus or blood clot in the blood vessel.

The process of the interaction of BLOOD COAGULATION FACTORS that results in an insoluble FIBRIN clot.

Cell adhesion molecule and CD antigen that mediates the adhesion of neutrophils and monocytes to activated platelets and endothelial cells.

Platelet membrane glycoprotein complex essential for normal platelet adhesion and clot formation at sites of vascular injury. It is composed of three polypeptides, GPIb alpha, GPIb beta, and GPIX. Glycoprotein Ib functions as a receptor for von Willebrand factor and for thrombin. Congenital deficiency of the GPIb-IX complex results in Bernard-Soulier syndrome. The platelet glycoprotein GPV associates with GPIb-IX and is also absent in Bernard-Soulier syndrome.

Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.

A subclass of purinergic P2Y receptors that have a preference for ADP binding and are coupled to GTP-BINDING PROTEIN ALPHA SUBUNIT, GI. The P2Y12 purinergic receptors are found in PLATELETS where they play an important role regulating PLATELET ACTIVATION.

A phospholipid derivative formed by PLATELETS; BASOPHILS; NEUTROPHILS; MONOCYTES; and MACROPHAGES. It is a potent platelet aggregating agent and inducer of systemic anaphylactic symptoms, including HYPOTENSION; THROMBOCYTOPENIA; NEUTROPENIA; and BRONCHOCONSTRICTION.

Use of a thrombelastograph, which provides a continuous graphic record of the physical shape of a clot during fibrin formation and subsequent lysis.

An unstable intermediate between the prostaglandin endoperoxides and thromboxane B2. The compound has a bicyclic oxaneoxetane structure. It is a potent inducer of platelet aggregation and causes vasoconstriction. It is the principal component of rabbit aorta contracting substance (RCS).

Tests based on the biochemistry and physiology of the exocrine pancreas and involving analysis of blood, duodenal contents, feces, or urine for products of pancreatic secretion.

A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).

Very large BONE MARROW CELLS which release mature BLOOD PLATELETS.

A subnormal level of BLOOD PLATELETS.

A high-molecular-weight plasma protein, produced by endothelial cells and megakaryocytes, that is part of the factor VIII/von Willebrand factor complex. The von Willebrand factor has receptors for collagen, platelets, and ristocetin activity as well as the immunologically distinct antigenic determinants. It functions in adhesion of platelets to collagen and hemostatic plug formation. The prolonged bleeding time in VON WILLEBRAND DISEASES is due to the deficiency of this factor.

Platelet membrane glycoprotein IIb is an integrin alpha subunit that heterodimerizes with INTEGRIN BETA3 to form PLATELET GLYCOPROTEIN GPIIB-IIIA COMPLEX. It is synthesized as a single polypeptide chain which is then postranslationally cleaved and processed into two disulfide-linked subunits of approximately 18 and 110 kDa in size.

Spontaneous or near spontaneous bleeding caused by a defect in clotting mechanisms (BLOOD COAGULATION DISORDERS) or another abnormality causing a structural flaw in the blood vessels (HEMOSTATIC DISORDERS).

Laboratory tests for evaluating the individual's clotting mechanism.

Human alloantigens expressed only on platelets, specifically on platelet membrane glycoproteins. These platelet-specific antigens are immunogenic and can result in pathological reactions to transfusion therapy.

A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.

Compounds that bind to and block the stimulation of PURINERGIC P2Y RECEPTORS. Included under this heading are antagonists for specific P2Y receptor subtypes.

Physiologically active compounds found in many organs of the body. They are formed in vivo from the prostaglandin endoperoxides and cause platelet aggregation, contraction of arteries, and other biological effects. Thromboxanes are important mediators of the actions of polyunsaturated fatty acids transformed by cyclooxygenase.

Retraction of a clot resulting from contraction of PLATELET pseudopods attached to FIBRIN strands. The retraction is dependent on the contractile protein thrombosthenin. Clot retraction is used as a measure of platelet function.

Emulsions of fats or lipids used primarily in parenteral feeding.

Oil from soybean or soybean plant.

Colloids formed by the combination of two immiscible liquids such as oil and water. Lipid-in-water emulsions are usually liquid, like milk or lotion. Water-in-lipid emulsions tend to be creams. The formation of emulsions may be aided by amphiphatic molecules that surround one component of the system to form MICELLES.

FATTY ACIDS found in the plasma that are complexed with SERUM ALBUMIN for transport. These fatty acids are not in glycerol ester form.

An abnormal lipoprotein present in large amounts in patients with obstructive liver diseases such as INTRAHEPATIC CHOLESTASIS. LP-X derives from the reflux of BILE lipoproteins into the bloodstream. LP-X is a low-density lipoprotein rich in free CHOLESTEROL and PHOSPHOLIPIDS but poor in TRIGLYCERIDES; CHOLESTEROL ESTERS; and protein.

An intravenous anesthetic agent which has the advantage of a very rapid onset after infusion or bolus injection plus a very short recovery period of a couple of minutes. (From Smith and Reynard, Textbook of Pharmacology, 1992, 1st ed, p206). Propofol has been used as ANTICONVULSANTS and ANTIEMETICS.

Men and women working in the provision of health services, whether as individual practitioners or employees of health institutions and programs, whether or not professionally trained, and whether or not subject to public regulation. (From A Discursive Dictionary of Health Care, 1976)