fibrinopeptide-a and Blood-Platelet-Disorders

Topics: Angina Pectoris; Blood Coagulation Disorders; Blood Platelet Disorders; Coronary Disease; Coronary Vasospasm; Fibrinopeptide A; Humans; Myocardial Infarction; Prostaglandins; Thromboxanes

The blood volumes and concentrations of thromboxane B2 (TxB2), platelet factor 4 (PF4), and fibrinopeptide A (FPA) were measured every 30 seconds in bleeding-time blood in normal subjects and in patients with idiopathic thrombocytopenic purpura (ITP), delta and alpha delta storage pool deficiency (SPD), Bernard-Soulier Syndrome (BSS), thrombasthenia (TSA), and von Willebrand's disease (vWD). Data were fitted to second-order (TxB2, PF4, and FPA) or third-order (volumes) polynomials. Average values for various parameters over fixed-time intervals were determined by numerical methods. The bleeding time was greater than 15 minutes in all patient groups and the initial bleeding, as reflected by the initial slope of the fitted blood volume curves, was increased in ITP, BSS, and SPD (delta-SPD in particular), but not in vWD and TSA. The increased values for both the initial slope and the volume of blood collected after 2 minutes in SPD suggest that vascular tone may be modulated, in part, by dense granule substances such as adenosine triphosphate (ATP) or serotonin. In TSA, uniquely, both platelet (TxB2 and PF4) and coagulation (FPA) values were increased in early bleeding samples (initial slope). In vitro studies of TxB2 production, together with previous flow studies of fibrin formation, also suggest enhanced activation and coagulant properties of thrombasthenic platelets. In other patients, reduced values of all substances at later times may reflect impaired platelet-fibrin plug formation in the high-shear regions at the ends of transected blood vessels. However, the initial slopes of the fitted curves for both TxB2 and PF4 were normal in vWD, suggesting that the early appearance of these substances may typically be from platelets that are adherent to collagen within the lower shear environment of the wound surface. The finding that FPA values were not decreased initially in any patient group, including ITP, but were decreased at later times (except for TSA), suggests that early fibrin formation occurs independently of platelets in the low-shear environment of the wound surface, whereas at later times fibrin is formed in a platelet-dependent manner in the high-shear regions at the ends of transected vessels.

Topics: Adult; Bernard-Soulier Syndrome; Bleeding Time; Blood Platelet Disorders; Fibrinopeptide A; Humans; Kinetics; Middle Aged; Platelet Factor 4; Platelet Membrane Glycoproteins; Platelet Storage Pool Deficiency; Purpura, Thrombocytopenic, Idiopathic; Thromboxane B2; von Willebrand Diseases

Plasma and serum assays of beta-thromboglobulin (BTG) and platelet factor 4 (PF4), and plasma fibrinopeptide A (FPA) were measured in adults with cyanotic congenital heart disease to characterize further the hemostatic disorder. Artifactual elevations of plasma BTG, PF4, and FPA appeared to occur occasionally when a 21 or 22 gauge needle was used to collect blood. The high packed red cell volume was probably the cause. Use of a larger caliber needle (20 gauge) appeared to lessen the problem. Normal plasma FPA levels (20 gauge needle) in 8 of 9 patients suggest that chronic intravascular coagulation is not common in these patients. Serum BTG and PF4, used to estimate total platelet content of these proteins, were normal to slightly increased. That levels were not reduced implies that platelets do not usually circulate in a "spent" state. Therapeutic phlebotomy in 8 patients was associated with small decreases in plasma BTG and PF4 of uncertain clinical significance. Five of 14 patients had elevated plasma BTG with normal to only minimally increased plasma PF4. However, 10 of 10 patients tested were found to have reduced creatinine clearance, and therefore the relative contributions of platelet secretion and reduced BTG catabolism in the kidney to elevated plasma BTG levels are unclear.

Topics: Adolescent; Adult; Animals; Beta-Globulins; beta-Thromboglobulin; Blood Coagulation Factors; Blood Platelet Disorders; Blood Specimen Collection; Fibrinogen; Fibrinopeptide A; Heart Defects, Congenital; Humans; Macaca mulatta; Middle Aged; Needles; Platelet Factor 4; Polycythemia; Radioimmunoassay; Rats; Thrombocytopenia