Oral contraceptive pills and hormonal replacement therapy and thromboembolic disease.

The risk of thromboembolic complications with the use of second and third generation oral contraceptives is minimal and probably related to underlying congenital or acquired thrombophilic states. Estrogen dose-dependency leads to increased thrombin generation and increased plasmin generation. There is no convincing evidence that the balance between clotting and fibrinolysis is disturbed. The risk of venous thromboembolism with pregnancy is greater than with oral contraceptives. Hormone replacement therapy is safe for healthy women, and the benefits far outweigh the potential risks.

Disseminated intravascular coagulation (DIC).

DIC is a life-threatening complication of several disease states. It is characterized by systemic activation of the hemostasis system. In many instances the release of tissue factor (TF) from endothelial cells or other circulating cells triggers the system. Initially, the increased activation can be compensated for by the natural inhibitor systems, a state referred to as compensated DIC. As the trigger persists, inhibitors will be consumed leading to more coagulation. In this process many clotting factors, most notably fibrinogen and platelets are consumed, resulting eventually in a complete breakdown of the hemostasis system. This results in a profuse and diffuse bleeding tendency or decompensated DIC. The term consumptive coagulopathy denotes this process. Of crucial importance is the fate of fibrin that is formed from fibrinogen by thrombin. If the fibrinolytic system is insufficiently activated, fibrin will be deposited in the microcirculation leading to MODS. This will not occur if the fibrinolytic system is fully activated. The clinical suspicion of DIC must be confirmed by laboratory tests and decreasing fibrinogen levels and platelet counts support the diagnosis. The determination of D-dimer, fibrin(ogen) split products (FSP) and soluble fibrin monomer (FM) further support the diagnosis. FM suggest the presence of thrombin, FSP the generation of plasmin, and D-dimer, both thrombin and plasmin. While the tests are not specific for DIC, they can be helpful, in the proper clinical setting, to diagnose decompensated or acute DIC. The tests are not useful for the diagnosis of compensated DIC, except for D-dimer, FSP, and FM if elevated. Compensated DIC can be diagnosed by molecular markers of in vivo hemostasis activation, such as thrombin-antithrombin (TAT) complexes, prothrombin fragment 1 + 2 (F 1 + 2), or plasmin-antiplasmin (PAP) complexes. For the treatment of DIC it is imperative to remove the triggering underlying disease. The consumption of coagulation constituents can be corrected by cryoprecipitate, platelet concentrates, and fresh frozen plasma, if needed. This may reduce the bleeding tendency. Arrest of the activated hemostasis system by heparins, either subcutaneous in low doses or intravenous in therapeutic doses, is only recommended in patients with compensated DIC. If the patient bleeds, heparins should not be given. The administration of concentrates of natural anticoagulants, i.e., antithrombin, protein C, or tissue factor pathway inhibitor are safer than heparins since they do not exacerbate the bleeding tendency. These concentrates were found to be very effective in animal models of DIC; human experience is still limited. Generally, the earlier treatment is initiated, the better the patient's prognosis.

Sticky platelet syndrome.

The sticky platelet syndrome (SPS) is an autosomal dominant platelet disorder associated with arterial and venous thromboembolic events. It is characterized by hyperaggregability of platelets in platelet-rich plasma with adenosine diphosphate (ADP) and epinephrine (type I), epinephrine alone (type II), or ADP alone (type III). Clinically, patients may present with angina pectoris, acute myocardial infarction (MI), transient cerebral ischemic attacks, stroke, retinal thrombosis, peripheral arterial thrombosis, and venous thrombosis, frequently recurrent under oral anticoagulant therapy. Clinical symptoms, especially arterial, often present following emotional stress. Combinations of SPS with other congenital thrombophilic defects have been described. Low-dose aspirin treatment (80 to 100 mg) ameliorates the clinical symptoms and normalizes hyperaggregability. The precise etiology of this defect is at present not known, but receptors on the platelet surface may be involved. Normal levels of platelet factor 4 (PF4) and beta-thromboglobulin in plasma suggest that the platelets are not activated at all times; they appear to become hyperactive upon ADP or adrenaline release. In vivo clumping could temporarily or permanently occlude a vessel, leading to the described clinical manifestations. The syndrome appears to be prominent especially in patients with unexplained arterial vascular occlusions.

The effects of a low-dose monophasic preparation of levonorgestrel and ethinyl estradiol on coagulation and other hemostatic factors.

OBJECTIVE: This study was undertaken to evaluate the effects on hemostatic factors of a low-dose preparation of levonorgestrel and ethinyl estradiol in a 12-cycle study. STUDY DESIGN: Thirty healthy women began taking 100 microg levonorgestrel and 20 microg ethinyl estradiol on the first day of the menstrual cycle, continued to take the preparation for the next 21 days, and then took placebo for 7 days. Mean changes in prothrombin time, partial thromboplastin time, and levels of factors VII and X, antithrombin, plasminogen, fibrinogen, protein S, thrombin-antithrombin complexes, and D-dimer were analyzed at baseline and at cycles 3, 6, and 12 with paired Student t tests. RESULTS: Factor X, plasminogen antigen and activity, and D-dimer levels were significantly increased (P

Low molecular weight heparins and heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) and HIT thrombosis syndrome (HITTS) are immune-mediated complications of clinical use of unfractionated heparin (UFH). The antibody/antigen complex is composed of heparin and platelet factor 4. This complex not only activates platelets but also the clotting system leading to thrombin generation. This explains the thrombosing tendency of these patients, and venous and arterial thromboembolisms are encountered with a morbidity and mortality of about 25-37%. The incidence of HIT is about 3% when UFH is administered therapeutically. The diagnosis is at this time based on clinical observations, especially a sudden, unexplained drop in platelet counts without other reasons. Laboratory tests can be used to confirm the clinical diagnosis, but none of the available tests is 100% reliable. There is no test that will predict HIT and no test that will signal the development of HITTS. Treatment consists of discontinuation of UFH in any form and anticoagulation with danaparoid or r-hirudin, if needed. The use of low molecular weight heparins instead of UFH could largely (not totally) alleviate the problem.

Therapeutic use of antithrombin concentrate in sepsis.

Sepsis and its associated complications of disseminated intravascular coagulation (DIC) and multiple organ dysfunction syndrome (MODS) continue to be a major cause of morbidity and mortality. Improved detection of all forms of DIC is essential to assure earlier diagnosis. Studies already indicate that the therapeutic use of antithrombin (AT) concentrate may produce a more positive outcome for sepsis-associated DIC. If DIC could be identified earlier and AT concentrate could then be given earlier in the sepsis continuum, study results for the use of AT concentrate in humans might reveal a statistically significant difference versus placebo, and the efficacy of AT concentrate for this syndrome is more likely to be proved. Fixed-bolus doses of AT concentrate based on body weight are currently preferred, but improved, user-friendly assays for plasma AT levels would permit more rapid turnaround time for AT results and could help fine-tune the use of AT concentrate to the specific needs of each patient. Clinical trials involving the therapeutic use of AT concentrate in sepsis should continue, and it can be hoped that their design will reflect the concepts and conclusions offered by this panel of investigators.

PFA-100 system: a new method for assessment of platelet dysfunction.

The PFA-100 system is a platelet function analyzer designed to measure platelet-related primary hemostasis. The instrument uses two disposable cartridges: a collagen/epinephrine (CEPI) and a collagen/ADP (CADP) cartridge. Previous experience has shown that CEPI cartridges detect qualitative platelet defects, including acetylsalicylic acid (ASA)-induced abnormalities, while CADP cartridges detect only thrombocytopathies and not ASA use. In this seven-center trial, 206 healthy subjects and 176 persons with various platelet-related defects, including 127 ASA users, were studied. The platelet function status was determined by a platelet function test panel. Comparisons were made as to how well the defects were identified by the PFA-100 system and by platelet aggregometry. The reference intervals for both cartridges, testing the 206 healthy subjects, were similar to values described in smaller studies in the literature [mean closure time (CT) 132 s for CEPI and 93 s for CADP]. The use of different lot numbers of cartridges or duplicate versus singleton testing revealed no differences. Compared with the platelet function status, the PFA-100 system had a clinical sensitivity of 94.9% and a specificity of 88.8%. For aggregometry, a sensitivity of 94.3% and a specificity of 88.3% were obtained. These values are based on all 382 specimens. A separate analysis of sensitivity by type of platelet defect, ASA use versus congenital thrombocytopathies, revealed for the PFA-100 system a 94.5% sensitivity in identifying ASA users and a 95.9% sensitivity in identifying the other defects. For aggregometry, the values were 100% for ASA users and 79.6% for congenital defects. Analysis of concordance between the PFA-100 system and aggregometry revealed no difference in clinical sensitivity and specificity between the systems (p > 0.9999). The overall agreement was 87.5%, with a Kappa index of 0.751. The two tests are thus equivalent in their ability to identify normal and abnormal platelet defects. Testing 126 subjects who took 325 mg ASA revealed that the PFA-100 system (CEPI) was able to detect 71.7% of ASA-induced defects with a positive predictive value of 97.8%. The overall clinical accuracy of the system, calculated from the area under the ROC curve, was 0.977. The data suggest that the PFA-100 system is highly accurate in discriminating normal from abnormal platelet function. The ease of operation of the instrument makes it a useful tool to use in screening patients for platelet-related hemostasis defects.

Antithrombin: its physiological importance and role in DIC.

Antithrombin (AT) is a single-chain glycoprotein in plasma and belongs to the family of the serpins. It is synthesized in liver parenchymal cells, and its plasma concentration is between 112-140 mg/L. AT is a unique inhibitor of the clotting system and neutralizes most of the enzymes generated during activation of the clotting cascade, especially thrombin, factors Xa and IXa. Equimolar, irreversible complexes are formed between AT and the enzymes. The interaction between AT and the activated clotting factors is at least 1,000-fold increased in the presence of heparins. Heparins bind to multiple sites of the AT molecule resulting in a steric reconfiguration. Heparins contain a specific pentasaccharide unit which is the minimum requirement for AT binding. The glycosaminoglycan (GAG) heparan sulfate found on endothelial cell surfaces also contains this pentasaccharide and can thus "activate" AT. It is believed that much of the physiological inactivation of enzymes by AT occurs on the endothelium, mediated by heparan sulfate. The binding of AT to the GAGs also releases prostacyclin which possesses strong antiinflammatory properties. Deficiencies of AT are inherited or acquired. Only acquired defects due to increased consumption are discussed, most notably AT in DIC, especially DIC in sepsis. During acute DIC, clotting factors and inhibitors are consumed faster than they can be reproduced. This consumption of AT is of great significance in DIC and sepsis, and plasma AT levels predict outcome. AT levels drop early in sepsis and laboratory signs of DIC can already be found in patients with SIRS and early sepsis. The important role of AT in DIC and sepsis is the basis for considering antithrombin concentrates as an additional therapeutic modality.

The haematological manifestations of sepsis.

Haematological changes in the septic patient are, primarily, neutropenia or neutrophilia, thrombocytopenia and disseminated intravascular coagulation (DIC). Thrombocytopenia frequently arises from DIC although inhibition of thrombopoiesis or immunological platelet damage also occur. DIC contributes to bleeding and microvascular thrombosis, leading to multiple organ failure. Tissue factor release, primarily mediated by tumour necrosis factor, activates the clotting system; fibrinolysis is initially activated, but later becomes inhibited by the release of plasminogen-activator inhibitor (PAI-1), further fostering multiple organ failure. Most septic patients have compensated, chronic DIC, detectable by assays of molecular markers; the earliest signs are already found during the systemic inflammatory response syndrome. Compensated DIC later becomes decompensated with rapid consumption of factors including inhibitors such as antithrombin III (AT III) and proteins C and S. AT III concentrations of < 60-70% of the normal values predict outcome. Management of DIC must address the underlying disease, interrupt the activated haemostasis system and replace consumed coagulation constituents. Interruption of haemostasis with heparin may be attempted, but bleeding may worsen. Administration of a natural anticoagulant, such as AT III, may arrest clotting without concomitant risk of bleeding. In several animal models of DIC, AT III concentrates shortened the duration of DIC and reduced multiple organ failure and mortality. Similar benefits have been reported in early studies of patients with DIC, especially in the absence of sepsis. Studies are under way to determine whether outcome will improve if patients with sepsis are treated before the development of shock and plasma AT III concentrations are maintained at 100-150% of normal.

Effects of warfarin on markers of hypercoagulability in patients with heart failure.

Heart failure is associated with a hypercoagulable state. A single-center, randomized, double-blind, placebo-controlled trial was performed to test the hypothesis that warfarin will modify a hypercoagulable state in heart failure. This study included 76 patients with heart failure. At baseline, patients had evidence for a hypercoagulable state with elevated plasma levels of thrombin/antithrombin III (TAT) complexes (3.4 +/- 2.0 ng/ml), prothrombin fragment F1 + 2 (1.5 +/- 0.9 nmol/L), and D-dimers (630 +/- 401 ng/ml). Warfarin therapy (international normalized ratio [INR] 2.7 +/- 1.3) significantly decreased plasma levels of TAT complexes (p < 0.002), F1 + 2 (p < 0.001), and D-dimers (p < 0.001) when compared with baseline values at 1, 2, and 3 months of therapy. In contrast, patients receiving placebo had persistent elevation of TAT complexes (p = not significant [NS]), F1 + 2 (p = NS), and D-dimers (p = NS) during follow-up at 1, 2, and 3 months. The two treatment groups followed different trends over time for all three markers (p < 0.001). The effect of low-intensity warfarin (INR 1.3 +/- 0.08) versus moderate-intensity warfarin (INR 2.3 +/- 1.1 ) on markers of hypercoagulability was evaluated in 14 patients. When compared with baseline, low-intensity warfarin administration decreased plasma levels of TAT complexes (p = NS), F1 + 2 (p = 0.05), and D-dimers (p = 0.04). In these patients F1 + 2 was further reduced with moderate-intensity warfarin (p < 0.001). Our findings suggest that a hypercoagulable state in heart failure can be modified by warfarin therapy.

In vitro platelet function in controlled ovarian hyperstimulation cycles.

OBJECTIVE: To determine the effects of elevated endogenous E2 levels on in vitro platelet function in patients undergoing controlled ovarian hyperstimulation (COH). DESIGN: Women with normal ovulatory cycles and patients undergoing COH on cycle day 3 and near ovulation (preovulatory follicles were at least 16 mm in diameter) were studied. Serum E2, Thrombostat 4000, (V. d. Goltz, Seeon, Germany), von Willebrand factor antigen (vWF-Ag), and platelet aggregation and adenosine triphosphate (ATP) release to adenosine diphosphate (ADP), collagen (COL), and arachidonic acid (AA) were measured. SETTING: University-based outpatient infertility clinic. PATIENT(S): Twenty-two consenting infertile women undergoing COH cycles and 14 women with documented ovulatory cycles. MAIN OUTCOME MEASURE(S): Whole blood platelet aggregation with ADP, COL, AA, and Thrombostat 4000. RESULTS(S): Estradiol levels rose significantly at peak times (P = 0.011). No changes were noted in in vitro platelet function measured by the Thrombostat 4000 and by whole blood platelet aggregation with ADP and AA and in ATP release with ADP, COL, or AA. Aggregation with collagen was increased because of likely elevations in vWF-Ag levels. CONCLUSION(S): No significant changes in in vitro platelet function were noted in 19 women undergoing COH with E2 levels two to three times that observed in oral contraceptive or hormone replacement therapy users, suggesting no increased risk for arterial thromboembolism.

Antithrombin levels related to infections and outcome.

Antithrombin (AT) was measured in the plasma of 59 trauma patients at Detroit Receiving Hospital from July 1987 through December 1992 to determine how well low AT levels correlated with the outcome and development of later infections. The average lowest AT measured was 74 +/- 14% (SD) (normal = 75 to 120%). The mean lowest AT of the 11 trauma patients who developed sepsis (45 +/- 13%) was significantly lower than that of the 15 who developed an infection without sepsis (66 +/- 12%) (p < 0.001) and of the 33 who did not develop an infection (87 +/- 15%) (p <0.001). No patient with an AT always > or = 70% became septic or died, and no patient with an AT always > or = 90% developed an infection. In the 33 patients who did not develop infections, the mean AT levels rose progressively from 75 +/- 17% during the first 48 hours after admission to 91 +/- 11% during the next 48 hours. In contrast, the mean AT levels in the 26 patients who later developed infections were significantly lower (48 +/- 24%) during the first 48 hours and 60 +/- 16% during the next 48 hours (p < 0.016 and p <0.001). Of 10 patients with an AT < 60% in the first 96 hours, 9 (90%) developed an infection later. Low levels of AT, thus, may be of help in predicting infection, outcome, or both in severely injured patients.

Performance characteristics and clinical evaluation of an in vitro bleeding time device--Thrombostat 4000.

The performance characteristics of an in vitro bleeding time device--Thrombostat 4000 were evaluated and compared with the Simplate bleeding time in healthy individuals and patients with disorders of primary hemostasis. Reference ranges were established using 30 normal volunteers. Although there were variations between different filter batches, reproducibility was good within a single batch. There were no differences between the two channels of the instrument and between male and female subjects. Hematocrit correlated negatively with the initial flow (IF) and IF correlated positively with closure time (T) and bleeding volume (V). Aspirin could be detected only when the traditional addition of ADP was replaced with CaCl2. Both, closure time (T) or bleeding volume (V) were more sensitive than Simplate bleeding time and T was more sensitive than V in detecting patients with disorders of primary hemostasis. We conclude that the Thrombostat 4000 is a reproducible, reliable, sensitive and easy to use instrument. It is superior to the traditional in vivo bleeding times for investigations of disorders of primary hemostasis (screening, diagnosis, monitoring, etc.).

Anabolic-androgenic steroid abuse in weight lifters: evidence for activation of the hemostatic system.

Anabolic-androgenic steroid abuse has recently been linked with acute vascular events in athletes. To date, the relationship between steroid abuse and the potential for cardiovascular disease has been considered almost exclusively in terms of lipid metabolism. However, recent reports of thrombosis in androgen abusing athletes with no evidence of atherosclerosis suggests the hypothesis that thrombosis risk in such athletes could be mediated through androgen induced abnormalities of coagulation. To determine if anabolic-androgenic steroid abuse in weight lifters is associated with an activation of the hemostatic system we studied forty-nine weight lifters recruited through advertisements. History of androgen use or abstinence was confirmed via urine assays. Plasma was assayed for clotting and fibrinolytic activity by measuring thrombin/antithrombin complexes (TAT), prothrombin fragment 1 + 1 (F1 + 2), and D-dimers (D-di); markers of the endothelial based fibrinolytic components were assayed by measuring tissue plasminogen activator antigen (t-PA Ag) and its inhibitor (PAI-1); finally, the activity of antithrombin III, protein C, and protein S were measured. Abnormally high concentrations of TAT complexes were noted in 16% of our confirmed steroid using weight lifters compared to 6% of our confirmed nonusers (P = .01). Steroid users also demonstrated abnormally high concentrations of F1 + 2 and D-dimers when compared to nonusers (44 vs. 24%, P < .001, and 9 vs. 0%, respectively). Non-steroid users were more likely to have elevated levels of t-PA Ag and PAI-1 than our steroid using weight lifters (both P < .001). The activities of antithrombin III and protein S were more likely to be higher in users compared to nonusers (22 vs. 6%, P = .005; 19 vs. 0%, respectively). Some anabolic-androgenic steroid using weight lifters have an accelerated activation of their hemostatic system as evidence by increased generation of both thrombin and plasmin. These changes could reflect a thrombotic diatheses that may contribute to vascular occlusion reported in young athletes using these drugs. The predictive value of these coagulation abnormalities in terms of risk of thrombosis to individual steroid using weight lifters or the population as a whole remains to be studied.

Hormonal contraception and platelet function.

PIP: 73 healthy women (29 controls, 25 using OCs, and 19 using Norplant) were selected from the clinic population at North Oakland Medical Center for inclusion in this study after obtaining informed consent. Age, race, height, weight, blood pressure, and cigarette smoking were recorded for each subject. 12 patients were on monophasic OCs while 13 were on triphasic preparations. Both hormonal contraceptive groups had used their particular contraceptive for at least 3 months prior to blood drawing. Platelet tests were performed within 2 hours of sample collection: platelet counts (PLC) and mean platelet volume (MPV) were determined on an Automated Platelet Counter (Baker 810 Platelet Analyzer). Whole blood aggregation was performed on a platelet aggregometer (Chrono-Log, Model 550) using both ADP (ADP, 5 mM) and collagen (COLL, 2 mcg/ml) as inducing agents. Demographic differences were not significant (p 0.05) among the 3 treatment groups, whose average age was 25.3-25.8 years old. Furthermore, no significant differences (p 0.05) in platelet function were detected among controls or subjects receiving either oral contraceptives or Norplant, compared to control patients. The mean platelet counts (X 10/9/L) were 223 for OC users, 231 for Norplant users, and 232 for controls. The respective platelet aggregation (ADP, ohms) values were 12.5, 18.0, and 19.2 as well as (COLL, ohms) 35.6, 40.7, and 39.0. These results demonstrated that there is no evidence for altered platelet function, with the testing methods employed, in women using either Norplant or combination low dose oral contraceptives. To date, several studies have examined this issue, with contradictory reports about the effects of hormonal contraceptives in platelet function. After controlling for differences between various steroid preparations and other such confounding variables, some of these conflicting conclusions could be the result of a lack of uniformity among the methods used to evaluate platelet aggregation. The ability to draw conclusions regarding altered in vivo thrombotic potential from these studies is thus questionable.^ieng

Clinical experience with the Thrombostat 4000.

Bleeding times are presently widely used to screen patients with primary hemostasis defects although their accuracy and reliability has been questioned by many investigators. Platelet aggregation studies are not suited for routine use. We investigated the performance characteristics of the Thrombostat 4000, a device that assesses primary hemostasis. Tests can be performed by adding ADP, epinephrine, CaCl2 or NaCl to the collagen onto which platelets adhere. It was found, using normal volunteers and patients, that ADP and epinephrine had acceptable reference ranges with coefficients of variance between 9-12% for within run and between runs. However, major differences were seen when different filter badges were used--a reflection of differences in collagen. Regular citrated blood, routinely drawn for coagulation studies, can be used; test performance can be delayed for up to five hours when the blood is kept at room temperature. The effects of aspirin on volunteers could be detected when epinephrine was used, but not with ADP. ADP addition allowed the detection of more patients with primary hemostasis defects than bleeding times, and epinephrine was as useful as ADP in detecting these abnormalities. The data suggest that the broadest spectrum of platelet defects (ASA use and platelet dysfunction) can be detected with epinephrine. Inconsistencies in collagen used for coating of the filters is a major drawback for the routine use of this device in screening primary hemostasis defects.

Preliminary data from a field trial of the PFA-100 system.

The PFA-100 system (Dade International Inc., Miami, FL) is a platelet function analyzer, the design of which is based on the technology of the Thrombostat 4000 VDG, Seeon, Germany. It was developed to measure primary, platelet dependent hemostasis in citrated whole blood in vitro. A first pilot study was conducted with the instrument to assess performance characteristics. Healthy subjects (normals) who had not ingested any medications, and patients (abnormals) with primary, platelet-related hemostasis defects, which included users of aspirin, were studied with two test cartridges; collagen/ADP and collagen/epinephrine. Before the study certain variables were tested that ascertained that blood drawn into either 3.8% or 3.2% sodium citrate containing vacutainers (rather than syringes) could be used for testing. Tests must be performed within a five-hour time span from drawing to testing, and blood must be kept at room temperature. Normal reference values were 77-133 seconds closure times for collagen/ADP and 98-185 seconds for collagen/epinephrine. Precision testing revealed a CV of < 10% for within-day and between-day (five days) analyses on collagen/ADP cartridges and a CV of 5-14% for both runs on the collagen/epinephrine cartridges. No clinically important differences were found between measurements in the two positions of the instrument, although one follows the other.(ABSTRACT TRUNCATED AT 250 WORDS)