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An artificial clotting system deficient in factor VIII has been made from normal human plasma. Factors XII and XI are supplied as `activation product'. An eluate from Al(OH), which has been incubated with normal plasma, supplies factors X and IX in their `plasma' (unactivated) form with II. Factor V is provided as the supernatant after the Al(OH)- treated plasma has been precipitated at one-third saturation with (NH)SO. Fibrinogen is freed of factor VIII by freezing and thawing a lyophylized preparation and then added. Of these, activation product and the fibrinogen may be prepared in advance and stored frozen, and the eluate and supernatant may be made on the day of testing. A phospholipid source and CaCl-solution are also required. In use, a patient's and a control plasma are first diluted in a mixture of the eluate, supernatant, and fibrinogen solution, and clotting times are recorded after completing the system by adding the phospholipid, activation product, and calcium chloride. The clotting times from the mixtures containing the patient's and the control plasmas may then be compared. [ABSTRACT FROM PUBLISHER]

Deficiencies of factor VIII (in haemophilia) and factor IX (in Christmas disease) prolong the partial thromboplastin time. If normal plasma is treated with alumina, the factor VIII remains but the factor IX is removed and can subsequently be recovered by elution of the alumina. If a long partial thromboplastin time is found on investigating a male patient whose history suggests a life-long bleeding disorder, the plasma may be retested after adding either alumina-adsorbed normal plasma or eluate. If the patient's partial thromboplastin time is shortened (relative to the control) by adding adsorbed normal plasma the patient is likely to be a haemophiliac; but if it is shortened by adding eluate then he is likely to have Christmas disease. Practical details for carrying out these manoeuvres are given and experiments on the validity of the test described. [ABSTRACT FROM PUBLISHER]

The partial thromboplastin time test provides a convenient and sensitive screening procedure for deficiencies of thromboplastic factors, especially factors VIII and IX. The test is carried out after preincubating the plasma for 10 minutes with kaolin, and Inosithin is used as a platelet substitute. The `normal range' of the test has been estimated in terms of the differences encountered between random normal plasmas tested in pairs, because individual patients are usually tested against single control subjects. A patient's partial thromboplastin time should be regarded as abnormal if it is more than six seconds longer than the control time. In the diagnosis of haemophilia, patients' plasmas with concentrations of factor VIII as low as about 20% might be regarded as being within the range of normal, if the selected control subject's factor VIII happened to lie near the lower end of the normal range. When mild haemophilia is suspected, discrimination may be improved by diluting both the patient's and the control plasmas 1 in 20 in haemophilic plasma. With the test modified in this way the clotting time is prolonged, though the range of differences among normal subjects is unaltered, and plasmas with factor VIII concentrations below about 30%, , in undiluted plasma, would be unlikely to be regarded as normal. The partial thromboplastin time may be similarly modified as a screening test for factor IX deficiency. Some clinical examples are reported. [ABSTRACT FROM PUBLISHER]

A method is proposed for the rapid estimation of plasma fibrinogen concentration. The technique depends on the increase of optical density occurring when plasma clots. A kit is described which obviates the use of laboratory apparatus, so that the test may be performed in the ward side-room if a small centrifuge can be provided. A calibration curve has been prepared for use with commercial opacity standards, and a measure of the error of the method has been obtained. [ABSTRACT FROM PUBLISHER]