SummaryThe thrombotic risk of women with a heterozygous natural clotting inhibitor deficiency taking oral contraceptives (OC) has not been evaluated. Therefore, a retrospective collaborative controlled cohort-study was carried out in 8 coagulation laboratories and thrombosis units in Austria, Germany and Switzerland.The incidence of thromboembolism in 48 females heterozygous for hereditary type I deficiency of antithrombin ITT (n = 1.5), protein C. (n = 16) or protein S (n = 17), who had taken OC at least once in their life were compared with that of 48 deficient women, who had never taken OC (controls). Diagnosis of the deficiency state was made in the participating centers. Data on the onset and duration of OC intake and the date and site of thrombotic events were obtained from a questionnaire filled in by the patient or a physician during a visit at a participating center. The observation period in the OC patients was started with onset of OC intake and was terminated when a thromboembolic event had occurred or when OC medication were discontinued. In the patients without OC, the observation period began at an age matched to that of the OC patient and ended when a thromboembolic event had occurred or was continued as long as the corresponding OC patient was on treatment.In AT Ill-deficient females the probability for thrombosis was significantly higher for patients taking OC compared to the non-OC-patients (Wilcoxon test p = 0.004, Log Rank test p = 0.005). In patients with protein C- ((3-error 0.8) and protein S-deficiency ((3-error 0.05) there was no significant difference between the OC- and non-OC-group. The incidence of thrombosis/patient year in AT III-, PC- and PS-deficient females on OC was 27.5%, 12% and 6.5%, respectively and 3.4%, 6.9% and 8.6%, respectively, in the control patients.We conclude that females with hereditary antithrombin Ill-deficiency are at high risk for venous thromboembolism when taking OC. Therefore, OC should be strictly avoided in these females and AT III measurement is mandatory in female relatives of AT Ill-deficient patients at young age before starting OC. There is no evidence for an excess thrombotic risk by OC intake in PS-deficient females. In protein C-deficient women OC medication was not associated with a significant increase of thrombosis, but an increased risk cannot be excluded.

High molecular weight (1MW) and low molecular weight (LMW) forms of von Wiflebrand factor (vWF) were isolated from normal human plasma in the presence of protease inhibitors. HMW and LMW vWF preparations were subjected to reduction of interdimeric diside bridges under mild reducing conditions. Foilowing sodium dodecyl sulfate eectrophoresis in 3% agarose, the vWF bands were detected by immunoblotting with a polyclonal rabbit anti-vWF antiserum as well as with two monoclonal antibodies dircted against epitopes located in the NHrterminal (MAb 418)

SummaryThe validity of the amidolytic Factor X assay for the control of long term oral anticoagulation (OA) was investigated in 42 patients randomized into 2 groups; PT group (anticoagulant dosage according to PT) and F. X group (anticoagulant dosage based on F. X). An independent expert's dosage according to F. X served for analysis in the former group. In the F. X group the F. X based dosage was considered valid only when not differing by more than 15% from the expert's PT based dosage.Confirming the good correlation between PT and F. X the study further demonstrates that the changes from one control to the next one, ΔPT and ΔF. X, too, are significantly correlated (r = 0.58, p & 0.001, n = 217). In over one third of the periods the dosage proposals based on PT and F. X were identical and differed by more than 15% in only 12/217 instances.Our results justify a large trial on the control of OA by the amidolytic F. X assay.

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