SYNOPSIS Factors V, VII, VIII, X, XI, and XII of the coagulation system, platelet count, and antithrombin III levels were assayed in 20 healthy volunteers aged 20-40 years and 61 elderly subjects aged 66-96 years whose skinfold thickness was also measured. Factors XI, XII, and antithrombin III levels tended to increase in women and decrease in men while factors X, VII, and V tended to increase in both males and females with advancing years. No age or sex differences were found in platelet counts or factor VIII levels. Factor VIII levels were inversely correlated with obesity in elderly males (r = -0-56, P < 0-005).

Experience with the use of streptokinase in the treatment of iliofemoral venous thrombosis is described. Streptokinase in a dose sufficient to induce systemic controlled defibrination was administered via an indwelling cannula which was used for repeated phlebography during the course of lysis and for several days afterwards. Of 40 patients treated, 10 had complete clearance and 24 partial clearance of the thrombus with the establishment of an iliofemoral channel. In 5 patients lysis did not occur and in 1 it was followed by early rethrombosis.

From the evidence presented, it is proposed that 'dysfibrinogenaemia' represents the production of normal fetal fibrinogen by rapidly proliferating liver cells in both regenerating and neoplastic tissue. Prolongation of the reptilase clotting time, which was formerly believed to reflect dysfibrinogenaemia, may be rather the result of hepatocytic death.

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The levels of plasminogen, α₁-antitrypsin, α₂-macroglobulin and the platelet count were measured in 511 blood donors. The mean level of α₁-antitrypsin was significantly lower in men of group B compared with that of group O. No other differences between the blood groups reached statistical significance. Women had higher mean levels of α₁-antitrypsin and α₂-macroglobulin and a higher platelet count than men. The levels of plasminogen and α₁-antitrypsin were significantly higher in women using oral contraceptives compared with those who were not. The level of α₂-macroglobulin fell with age until the 60–64 year age-group in men and the 40–49 year age-group in women. A positive correlation existed between the α₁-antitrypsin and the α₂-macroglobulin level and between the platelet count and the plasminogen level.