Significance of blood coagulation and platelet profiles in relation to pulmonary thrombosis in beta-thalassemia/Hb E.

In beta-Thalassemia hemoglobin E (beta-thal Hb E), hypoxemia with abnormal lung function was described and postmortem examination in these patients showed organized pulmonary trombi with thickened arterial wall, particularly in post-splenectomized cases. Coagulation and platelet profiles were studied in 58 beta-thal Hb E patients. In 35 cases with intact spleen, the fibrinolytic activity was significantly decreased with high antithrombin III activity, while coagulation tests revealed mild abnormality. The platelet aggregation to ADP, adrenaline, collagen and ristocretin were defective and platelet 5-hydroxytryptamine content was lower than normal. Twenty-three patients who had been splenectomized for 5-18 years, decreased fibrinolytic activity and high antithrombin III activity were also observed. The coagulation profiles and platelet aggregation in response to ADP, adrenaline and collagen showed better results. Fourteen cases exhibited thrombocytosis and their thrombin generation was in the hypercoagulable range. Platelet aggregation in response to ristocetin remained defective and platelet 5-hydroxytryptamine content was lower than in cases with intact spleens. Defective aggregation to ristocetin would indicate abnormal von Willebrand's factor (vWF). Decreased fibrinolysis should very likely have a role in the occurrence of thrombosis and the better hemostatic profiles in post-splenectomized cases would contribute to the more frequent thrombotic incidence in these cases.

Clinical study on antithrombotic effects of ticlopidine in ischemic stroke.

The investigators conducted a clinical study on antithrombotic effectiveness in ischemic stroke at Siriraj Hospital Medical School, Mahidol University from May 1987 to May 1989. Twenty-nine patients, 16 males and 13 females were enrolled in the study. The ages of the patients ranged from 30-87 years with a mean age of 63 +/- 11 years. Ticlopidine (250 mg) could significantly inhibit platelet aggregation induced by ADP and collagen within 24 hours of drug administration. After 1 week to 6 months, only aggregation by ADP was still inhibited significantly without significant effects on fibrinolytic activity and prostacyclin. Hematocrit was significantly decreased at the 1st and 2nd month of treatment. Serious side effects were skin rash and severe headache while the other common ones were dizziness, and diarrhea but these effects disappeared without discontinuing the drug. Most patients who suffered from nausea, diarrhea and headache, had temporary elevated SGPT. It may be concluded that only half of the recommended dose of ticlopidine has inhibitory effects on both phases of ADP-induced aggregation without interfering with fibrinolytic activity and can maintain prostacyclin. However, it also possesses either serious or common side-effects. This drug, therefore, should be used with the awareness of the clinician.

Low dose aspirin and its antithrombotic effect in ischaemic stroke patient.

The investigators conducted a study of low dose aspirin and antithrombotic effectiveness in ischaemic strokes at Siriraj hospital Medical School, Mahidol University from July 1986 to June 1987. Thirty-six patients, 27 males and 9 females were enrolled in the study. The ages of the patients ranged from 33 to 80 years with a mean age of 55 +/- 12 years. Forty-seven per cent of patients had hyperfunction of platelet before treatment which fell to 3 and 0 per cent 24 hours and 7 days after low dose aspirin treatment (75 mg/d). The platelet count was significantly increased to compensate its hypofunction after seven days of treatment. There was no change in euglobulin lysis time, serotonin level in platelet after low dose aspirin treatment. Plasma prostacyclin in ischaemic stroke patients was statistically significantly reduced in comparison to normal subjects (223.8 pg/ml); but there was no further suppression of plasma prostacyclin after low dose aspirin therapy. Thus, we conclude that low dose aspirin (75 mg/d) is effective for antithrombotic effect in ischaemic stroke patients without any suppression of prostacyclin. We do recommend low dose aspirin for recurrent ischaemic stroke prophylaxis as it has fewer side effects, is cheap, easily administered and effective.