Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THROMBELASTOGRAPHY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed2000

Inhaled prostacyclin and platelet function after cardiac surgery and cardiopulmonary bypass.

OBJECTIVE: To study the effects of 6 h inhalation of aerosolized prostacyclin (PGI2) on platelet function. DESIGN: In a prospective, double-blind, randomized study, 28 patients scheduled for elective cardiac surgery requiring cardiopulmonary bypass (CPB), received either 0.9% sodium chloride (n = 8), PGI2 5 microg x ml(-1) (n = 10) or PGI2 10 microg x ml(-1) (n = 10) as an aerosol for 6 h postoperatively. SETTING: Cardiothoracic intensive care unit at a university hospital. INTERVENTIONS: All patients were studied immediately after surgery during mechanical ventilation and sedation. The PGI2 solutions or saline were administered with a jet nebulizer. MEASUREMENTS AND RESULTS: Bleeding time and chest tube drainage were measured. Blood samples for platelet aggregation, thrombelastography (TEG) and analysis of coagulation parameters and the stable prostacyclin metabolite 6-keto-PGF1alpha were obtained immediately before inhalation and after 2, 4 and 6 h of inhalation. After 6 h of PGI2 inhalation, regardless of administered dose, there was a lower rate of platelet aggregation and a lower maximal increase in light transmission in response to adenosine diphosphate (ADP) than in the control group. The TEG variable reaction time (R) was prolonged after 4 and 6 h of inhalation in the PGI2 group receiving 10 microg x ml(-1). There were no differences between groups with respect to bleeding time and chest tube drainage or any of the other variables examined. CONCLUSION: Inhalation of PGI2 for 6 h in patients after cardiac surgery is associated with impaired platelet aggregation detected by in vitro techniques, with no in vivo signs of platelet dysfunction.

Administration, Inhalation↗
PubMed1991

The use of high dose aprotinin in liver transplantation: the influence on fibrinolysis and blood loss.

Orthotopic liver transplantation (OLT) is frequently associated with systemic fibrinogenolysis and diffuse bleeding. At present antifibrinolytic treatment has not been initiated routinely in OLT. Therefore the influence of high dose aprotinin in OLT (2 million kallikrein inactivator units (KIU) given after induction of anesthesia followed by a 500,000 KIU/h infusion throughout the operation) on intraoperative blood loss and fibrinolysis was studied in 25 patients compared to 25 patients without aprotinin. The incidence of fibrinolysis shown in thrombelastography was 72% in the control group versus 16% in the aprotinin group. Oozing after reperfusion of the graft caused by severe fibrinolysis defined as a clot lysis index below 15% was only observed in the control group (42.8%). In contrast no significant difference was found between the groups in the course of fibrin and fibrinogen degradation product levels (FbDP, FgDP) although the mean concentrations of both parameters were evidently lower in the aprotinin treated patients. Levels of tissue-type plasminogen activator (t-PA) activity were initially high in both groups and peaked during and after the anhepatic period. After aprotinin there was a trend of lower t-PA levels which reached significance at the time of reperfusion (p less than 0.02). In both groups the course of thrombin antithrombin complex was in line with the variations of FbDP and FgDP. No correlation between thrombin formation and t-PA activity was found. Mean homologous blood requirement was reduced by 50% (5.6 +/- 4.0 vs. 11.2 +/- 8.6 units, p less than 0.005). The blood saving effect was more pronounced in the postanhepatic period (p less than 0.000001). In conclusion high dose aprotinin inhibits hyperfibrinolysis and reduces intraoperative homologous blood requirement. Therefore its routine use in OLT is recommended.

Adult↗
PubMed2005

Disruption of graft endothelium correlates with early failure after off-pump coronary artery bypass surgery.

BACKGROUND: Saphenous vein graft failure after coronary artery bypass surgery may be as high as 5% to 10% in the first postoperative week. We hypothesized that identifying damage sustained by saphenous vein endothelium before grafting predicts early graft attrition after off-pump coronary artery bypass graft surgery. METHODS: Intraoperative graft flow, platelet function, and endothelial integrity were analyzed in 125 patients undergoing off-pump coronary artery bypass graft surgery. Endothelial integrity was assessed in an excess vein segment from each graft using immunohistochemistry (CD31 staining). Platelet function was monitored just before and immediately after revascularization and on postoperative days 1 and 3 using whole blood aggregometry, thrombelastography, and platelet activated clotting time. Platelet activation was monitored using flow cytometry. Intraoperative conduit blood flow, measured by transit time ultrasonography, was used to detect and rectify anastomotic problems. Early graft patency was determined on postoperative day 5 using gated multichannel computed tomography angiography. RESULTS: In 106 patients undergoing postoperative computed tomography evaluation, 10 vein grafts in 10 patients were discovered to have developed early thrombosis, representing 4% (10 of 217) of all vein grafts. Endothelial integrity was 10.75% +/- 17.56% in 10 grafts that failed early compared with 51.45% +/- 36.29% in patent grafts (p = 0.04). Perioperative platelet function and graft flow did not differ significantly between the two groups. CONCLUSIONS: Although endothelial disruption predicts early failure of bypass grafts, the importance of a hypercoaguable state and low graft flow as a cause of early graft thrombosis after off-pump coronary artery bypass graft surgery was not supported by our preliminary results. A means to assess, prevent, and treat intraoperative vein graft damage will likely improve early graft patency.

Aged↗
PubMed2005

Biological performances of collagen-based scaffolds for vascular tissue engineering.

Collagen is widely used for biomedical applications and it could represent a valid alternative scaffold material for vascular tissue engineering. In this work, reconstituted collagen films were prepared from neutralized acid-soluble solutions for subsequent haemocompatibility and cell viability performance assays. First, haemoglobin-free, thrombelastography and platelet adhesion tests were performed in order to investigate the blood contact performance. Secondly, specimens were seeded with endothelial cells and smooth muscle cells, and cell viability tests were carried out by MTT and SEM. Results show that neutralized acid-soluble type I collagen films do not enhance blood coagulation, do not alter normal viscoelastic properties of blood and slightly activate platelet adhesion and aggregation. Cell culture shows that the samples are adequate substrates to support the adhesion and proliferation of endothelial and smooth muscle cells.

Biocompatible Materials↗
PubMed2005

Platelet reactivity in patients and recurrent events post-stenting: results of the PREPARE POST-STENTING Study.

OBJECTIVES: We investigated the relation of high ex vivo platelet reactivity, rapid fibrin generation, and high thrombin-induced clot strength to postdischarge ischemic events in patients undergoing percutaneous coronary intervention (PCI). BACKGROUND: High platelet reactivity and rapid fibrin generation may affect the incidence of ischemic events after PCI. However, limited data is available to link these ex vivo markers to the occurrence of events. METHODS: We measured platelet reactivity to adenosine diphosphate (ADP) by light transmittance aggregometry (LTA) in patients undergoing PCI (n = 192). Clot strength, a measure of thrombin-induced fibrin and platelet interactions, and the time to initial fibrin generation, a marker of thrombin activity, were measured by thrombelastography. The relation of these measurements to ischemic event occurrence was prospectively examined over six months. RESULTS: A total of 100% and 84% of patients were on aspirin and clopidogrel therapy, respectively, at the time of the initial event. Posttreatment ADP-induced aggregation by LTA (63 +/- 12% vs. 56 +/- 15%, p = 0.02) and clot strength (MA) were higher (74 +/- 5 mm vs. 65 +/- 4 mm, p < 0.001) and time to initial fibrin generation was shorter (4.3 +/- 1.3 min vs. 5.9 +/- 1.5 min, p < 0.001) in patients with events (n = 38). The event rates in the highest quartiles of LTA and MA were 32% and 58%, respectively. CONCLUSIONS: High platelet reactivity and clot strength, and rapid fibrin formation are novel risk factors for ischemic events after PCI. Clot strength is more predictive than ADP-induced platelet aggregation and may explain the occurrence of events despite treatment with cyclooxygenase-1 and P2Y12 inhibitors.

Angioplasty, Balloon, Coronary↗
PubMed2004

Anesthetic and perioperative management of a patient with Bernard-Soulier syndrome.

We describe a patient with Bernard-Soulier syndrome who underwent emergency laparotomy for intraabdominal bleeding. Presentation of this recent case highlights some of the anesthetic and perioperative implications of the disease. Briefly, perioperative and anesthetic management of patients with Bernard-Soulier syndrome should include platelet transfusions and choice of appropriate anesthetic drugs and techniques. The potential benefit of desmopressin and corticosteroids should be considered. Thrombelastography, if available, is also useful.

Adult↗
PubMed1999

Correction of both prothrombin time and primary haemostasis by recombinant factor VII during therapeutic alcohol injection of hepatocellular cancer in liver cirrhosis.

We evaluated the efficacy of recombinant factor VII to correct impaired haemostasis in a patient with liver cirrhosis requiring an invasive procedure. A test intravenous bolus of 80 microg/kg of recombinant factor VII was given to a Jehovah's Witness, with a solitary 4.4-cm hepatocellular carcinoma and underlying hepatitis C virus cirrhosis, in an attempt to correct his haemostatic disorders and safely inject the tumour with alcohol. An extensive portal block had precluded consideration of liver transplantation. Haemostasis was evaluated by clotting assays, bleeding time and thromboelastography 10 min before and 10 min and 1, 2, 4, 8 and 24 h after factor VII infusion. Parameters of both coagulation (prothrombin time) and platelet function (bleeding time and the alpha and ma parameters of thrombelastography) were improved 10 min after factor VII infusion; improvements lasted 4 to 8 h or more. Platelet count did not change and there was no evidence of disseminated intravascular coagulation. The improvements in haemostatic parameters correlated significantly with the increases in factor VII plasma concentrations (p<0.04). Factor VII clearance was 25.1 U/h/kg and its half-life was 5.8 h. The same dose of recombinant factor VII was given to the patient 1 week later, just before the alcohol injections. The patient had no subsequent bleeding or other complication, with no change in haemoglobin levels over 24 h. Thus, recombinant factor VII represents a therapeutic advance, as it can correct fully both coagulation and platelet function defects in cirrhosis and allow invasive procedures to be performed safely.

Carcinoma, Hepatocellular↗
PubMed2000

Phospholipase A2-induced coagulation abnormalities after bee sting.

We will examine the correlation between various bee venom phospholipase A2 (PLA2) concentrations and several parameters of coagulation in human plasma in order to offer a rationale for requesting a particular laboratory coagulation test after bee sting(s). We will also evaluate in vitro the influence of clinically available drugs with a noncompetitive inhibitory effect on PLA2 on the anticoagulant effect of bee venom PLA2. Prothrombin index (PTi), partial thromboplastin time (PTT), antithrombin III (AT III), soluble fibrin monomers (SFM), the activity of coagulation factors I, II, V, and VIII, and thrombelastography (TEG) parameters (split point [Sp], reaction time [R], kinetic time [K], coagulation time [R + K], maximal amplitude [MA], and the growth angle [alpha]) were determined before and after addition of 1.4, 2.7, and 4.1 units (1, 2, and 3 microg protein respectively) of bee venom PLA2. Linear regression was used to determine the significance of the relationship between these coagulation parameters and bee venom PLA2 concentrations used. To study the influence of ketamine, lidocaine, magnesium, furosemide, and cromolyn on the anticoagulant effect of bee venom PLA2, PTi and factor II- and V-activities were measured before and after addition of 2.7 units of PLA2 and PLA2 plus one of the tested substances. Determinations of F II, PTi, F V, and F VIII showed a negative correlation to bee venom PLA2 concentration (r = -0.88, -0.86, -0.81, and -0.79 respectively). A positive correlation was found for PTT (r = 0.69). FII- activity and PTi correlated better with bee venom PLA2 concentration than other parameters. F I, AT III, and SFM showed no changes. Whereas Sp, R, and K were prolonged by bee venom PLA2 and a was reduced, there was no correlation to the PLA2 concentration. Addition of none of the 5 substances could correct the effects of bee venom PLA2 on the coagulation. In a patient with toxic reaction or a severe anaphylactic reaction after bee sting(s) we suggest determinations of FII and/or PTi. This will allow a quick and economical assessment of coagulation abnormalities after bee sting(s). Noncompetitive PLA2-inhibitors (ketamine, lidocaine, magnesium, furosemide, and cromolyn) are unable to correct in vitro the anticoagulant effect of bee venom PLA2. They cannot be recommended at this stage for this purpose. Further investigations with competitive PLA2-inhibitors are warranted.

Animals↗
PubMed2003

[The value of platelet function tests].

Platelet function tests are used to detect patients with abnormal platelet function, which may be inborn or acquired or to detect increased platelet activation which may be accompanied by an increased risk of thrombosis. Platelet function tests are also used to monitor platelet function inhibitors as aspirin, clopidogrel or platelet membrane glycoprotein IIb/IIIa-inhibitors. Incorrect blood sampling is a major source of error in measuring platelet function. Global tests besides platelet count and bleeding time are thrombelastography, the platelet function analyzer (PFA) and possibly in the future the new Impact-system. Specific tests measure platelet spreading and adhesion to defined surfaces. In a series of methods platelets are counted before and after passage of a filter. Some of these tests are partially standardized. The most frequently measured platelet function is aggregation induced by ADP, collagen or other substances as first described by Gustav Born. Some newer methods to perform aggregometry are described. Platelet activation can be detected by measuring spontaneous aggregation as in the PAT-test. Prospective trials with this test have shown that enhanced spontaneous aggregation is a risk factor for new vascular occlusions in diabetics and for myocardial infarctions in healthy individuals. The Wu and Hoak-test and the measurement of released platelet factor 4 or betaglobulin are of limited value. Flow cytometric methods are frequently used to measure platelet activation markers as CD 62 and others. Platelet induced thrombin generation is an interesting function to measure drug effects. None of the presently available platelet function tests is well standardized, so there is much room for improvement.

Blood Platelet Disorders↗
PubMed1996

Thrombelastographic evaluation of coagulation in transurethral prostatectomy.

OBJECTIVE: To assess the changes in overall coagulation status and define the degree of systemic fibrinolysis occurring in patients undergoing transurethral prostatectomy (TURP). PATIENTS AND METHODS: Thirty patients undergoing TURP, 23 for benign prostatic hyperplasia and seven for prostatic carcinoma, were studied prospectively. Serial venous blood samples were taken using the two-syringe technique. Samples were taken before, during and at intervals up to 72 h and 10-14 days after surgery. Thrombelastography (TEG) was performed on native whole blood samples. Peri-operative blood loss was assessed, until the catheter was removed, by photometric estimation of the haemoglobin content of the irrigant fluid and the measurement of clot volume. RESULTS: There was no evidence of fibrinolysis (TEG Percentage Clot Lysis Ly60 > 15%) in any patient over the whole peri-operative period. There was a significant change in the mean TEG variables towards hypercoagulation from 3 h until 10-14 days postoperatively, compared with the pre-operative values (P < 0.05). There was a significant correlation between blood loss and clot volume. CONCLUSION: These results question the role of systemic fibrinolysis in primary and secondary haemorrhage following TURP and thus the rationale of using antifibrinolytics in these patients. The persistent hypercoagulable state post-operatively indicates a possible role of hypercoagulability in clot retention.

Blood Coagulation↗
PubMed2001

Influence of coconut water on hemostasis.

Coconut water (CNW) can be used as short-term intravenous hydration and resuscitation fluid. We investigated the influence of coconut water on plasma coagulation in vitro. Either CNW or physiological saline (PS) was added to citrated plasma of 8 healthy volunteers. Coagulation capability of diluted plasma was evaluated by thrombelastography (TEG). Replacement of up to 50 % of citrated plasma by CNW or PS did not influence initiation of coagulation as indicated by split point and reaction time, respectively. Strength of fibrin clot as expressed by maximum amplitude (MA) of TEG recording dose dependently declined in both groups. Replacing 50 % of citrated plasma by CNW or PS reduced MA by 39% and 32%, respectively. The influence of coconut water on hemostasis as assessed by TEG does not differ from the effect caused by an identical volume of PS.

Blood Coagulation↗
PubMed2004

Understanding the hemostatic effects of recombinant factor VIIa by clot wave form analysis.

The monitoring of coagulation-inhibitor bypassing agents, including recombinant factor VIIa (rFVIIa), remains a major issue in the management of clinical hemophilia. Clotting assays using prothrombin time (PT) and measurements of factor VII (FVII) activity do not always reflect the hemostatic effects of treatment. Thrombelastography can be used to observe the global effects of treatment on the overall coagulation process and is especially useful for observing the effects of hemostatic treatment in hemophilia patients with inhibitors. Waveform analysis is another technique for evaluating global hemostatic condition where changes in light transmission during routine clotting assays, such as the activated partial thromboplastin time (aPTT), are measured. We found that waveforms differed between individual patients with severe hemophilia A (FVIII:C < 1.0 IU/dL) with levels of sensitivity at below FVIII:C 1.0 IU/dL. Clot waveforms indicated dose-dependent improvements in clot formation after the addition of rFVIIa to both FVIII-deficient and factor IX (FIX)-deficient plasma. The improvements were further enhanced in the presence of both platelets and synthetic phospholipids, and were more pronounced with FVIII-deficient plasma than with FIX-deficient plasma. It appears that clot waveform analysis provides a very useful means for monitoring hemostasis in hemophilia A patients with inhibitors.

Blood Coagulation↗
PubMed2006

High-dose recombinant factor VIIa therapy in hemophilia patients with inhibitors.

Recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark) is well established as an effective hemostatic agent for the management and prophylaxis of hemorrhage in hemophilia patients with inhibitors. Treatment schedules usually involve multiple bolus doses of 90 to 120 microg/kg administered every 2 to 3 hours, but recent evidence suggests that the use of higher doses might be justified. Such high-dose regimens may overcome the rapid clearance rate observed in pediatric patients, and may be more convenient for patients with poor venous access. It has been suggested that individually tailored high-dose therapies might be beneficial in selected groups of patients, although careful monitoring of such patients is advised. Thrombelastography has demonstrated considerable success in this regard, allowing accurate assessment of both hemostatic efficacy and individual response to rFVIIa. To date, no safety issues associated with high-dose rFVIIa have been identified. However, it is hoped that further research will support these favorable observations and thus contribute towards more effective dose optimization of rFVIIa in hemophilic inhibitor patients.

Blood Coagulation Factor Inhibitors↗
PubMed1995

Therapeutic use of phospholipids in thrombocytopenic or thrombocytopathic patients.

Eight thrombocytopenic/pathic patients received an intravenous infusion of phospholipids. In vitro bleeding test (Thrombostat 4000), thrombelastography, and resonance thrombography were performed in order to show the hemostatic effect. In none of the cases did phospholipids exert an effect comparable to platelet transfusion. Two patients, brother and sister, had a severe anaphylactoid reaction after the administration of phospholipids.

Adolescent↗
PubMed2004

[Dilutional coagulopathy, an underestimated problem?].

When no fresh frozen plasma is available, acute major blood loss is compensated above all with crystalloids, colloids and erythrocyte concentrates, meaning that all plasma clotting factors are diluted. Consumption coagulopathy is almost always accompanied by dilutional coagulopathy. Formulas for calculating critical blood loss and standard coagulation tests are often not helpful in the case of massive transfusion. On the other hand, systems suitable for point of care, such as thrombelastography, have important advantages. In the case of consumption and dilutional coagulopathy plasma coagulation is disturbed and critical values are first seen for fibrinogen. Not only is fibrin polymerization impaired by the bleeding-induced loss and dilution of fibrinogen, but also by interaction with artificial colloids, particularly hydroxyethyl starch preparations. Therapy of consumption and dilutional coagulopathy calls for fresh frozen plasma. If this is not available in sufficient quantity or within a reasonable time, coagulation factor concentrates must be used. Neither fresh frozen plasma therapy nor treatment with coagulation factor concentrates has been the subject of detailed clinical study. Further studies are needed to work out guidelines for coagulation management in the case of massive blood loss.

Blood Coagulation↗
PubMed1989

Comparative human pharmacology of low molecular weight heparins.

The pharmacodynamics of LMW heparins differ consistently from those of normal heparin. The relative bioavailability is greater than 90% and for some LMW heparins more than 100% after subcutaneous administration, as measured by the anti-Factor Xa activity. This indicates release of endothelial bound glycosaminoglycans with anti-Factor Xa-like activities. Direct determination of the LPL and HTGL activities demonstrate higher capacities of two and a lower capacity of three LMW heparins to release these enzymes from their endothelial glycoprotein receptors into the bloodstream. Thus, all LMW heparins are characterized by improved pharmacodynamics compared with normal heparin, but their anti-Xa to APTT and anti-Xa to anti-IIa ratios and half-lives differ among each other. The neutralization of the anticoagulant effects of LMW heparins by protamine are similar in vitro and in vivo at equigravimetric doses. However, unfractionated heparin and LMW heparins are not completely antagonized by protamine on a whole blood clotting test (thrombelastography). This inhibition of Factor Xa of LMW heparins is counteracted not completely by protamine. This may be due to a release of other glucosaminoglycans by LMW heparins. The present overview demonstrates that a comparative human pharmacology gives useful devices for prophylactic and therapeutic regimen for LMW heparins in patients in addition to the data obtained from animal models.

Animals↗
PubMed2002

Absence of compensatory platelet activation in patients with severe haemophilia, but evidence for a platelet collagen-activation defect.

Severe haemophilia is a serious, haemorrhagic disorder of the plasmatic coagulation system. In this study we investigated, whether 'compensatory' activation of the platelet coagulation system occurs in this situation. Platelet function was investigated with aggregation, adhesion and flow cytometric assays. In addition, we performed clot and platelet plug formation tests and determined endogenous thrombin potentials in patients with severe haemophilia A or B; results were compared to those of healthy controls. Platelet aggregation in response to stimulation with ADP, ristocetin and epinephrine was similar in patients and controls; aggregation in response to collagen was reduced significantly in haemophiliacs. Flow cytometric analysis of P-selectin (CD 62P) and CD 63, of the conformationally changed GP IIb/IIIa with PAC 1 and of thrombospondin bound to CD 36 (GP IV) was performed at baseline and post stimulation. Baseline expression of all markers was similar in haemophiliacs and controls. After stimulation of the platelet thrombin receptors with the thrombin receptor activating peptide (TRAP) 6, the surface expression of all markers increased significantly; again, the expression was similar in haemophiliacs and controls. With thrombelastography and PFA 100 analysis, clot formation under low shear and platelet plug formation under high shear is measured. Both test results revealed a significantly reduced clot and platelet plug formation capacity in severe haemophiliacs. Our results did not reveal signs of enhanced platelet preactivation in haemophiliacs, indicating that baseline platelet reactivity in severe haemophilia remains in a neutral state, despite the severely haemorrhagic condition. As expected, both thrombin and clot formation capacities were impaired significantly in severe haemophilia. The reduced response to collagen-based platelet stimulation tests is indicative of a concomitant platelet function defect. This defect probably contributes to the intensity of bleeding events in patients with severe haemophilia.

Adenosine Diphosphate↗
PubMed2004

The platelet function defect of paroxysmal nocturnal haemoglobinuria.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, acquired stem cell disorder, characterised by an abnormal susceptibility of red blood cells to complement induced lysis, resulting in repeated episodes of intravascular haemolysis and haemoglobinuria, thromboembolic events at atypical locations and, to a much lesser extent, bleeding complications. Platelet function is assumed to be abnormal, however, a defect has not yet been characterised and underlying mechanisms remain elusive. To explore these issues, we investigated platelet function in PNH patients using assays for clot formation under low and high shear force (thrombelastography and PFA100 device), adhesion to glass beads in native whole blood (Hellem method), aggregometry using various agonists (Born method), and flow cytometric assays for baseline and agonist-induced surface expression density of alpha-granule (CD62P) and lysosomal granule proteins (CD63), ligand binding to surface receptors (thrombospondin), and expression density of activation-induced neoepitopes of the fibrinogen receptor complex (PAC-1). Platelet PNH clone size determined by CD55 and CD59 labelling was compared to the clone sizes of granulocytes, monocytes, erythrocytes, and reticulocytes. A profound reduction of platelet reactivity was observed in PNH patients for all "global function" assays (clot formation, adhesion, aggregation). Platelet hyporeactivity was confirmed using flow cytometric assays. Whereas baseline levels of flow cytometrically determined platelet activation markers did not differ significantly between controls and PNH patients, agonist-induced values of all markers were distinctly reduced in the PNH group. Moreover, significantly reduced white blood cell counts (3.1/nl vs. 5.9/nl), haemoglobin values (9.5 vs. 14.3/g per dl), and platelet counts (136 vs. 219/nl) delineate profound tricytopenia in PNH patients. The fraction of particular cell types lacking the surface expression of GPI-anchored glycoproteins is referred to as the respective PNH clone; median PNH clone sizes of cells with short life spans (reticulocytes, platelets, granulocytes) was 50-80% of total cell populations compared to 20% of red blood cells. The results of our laboratory investigations show, that in PNH, reduced platelet counts coincide with reduced platelet reactivity. The foremost clinical complication in PNH, however, is venous thromboembolism, very probably induced by an activated and dysregulated plasmatic coagulation system. From these seemingly contradictory findings we infer, that part of the platelet hyporeactivity is probably due to reactive downregulation of platelet function in response to chronic hyperstimulation. The overall result is thought to be an unsteady balance, associated with thromboembolism in a larger proportion of patients, and with bleeding in a smaller proportion.

Adolescent↗