Validity of D-dimer tests in the diagnosis of deep vein thrombosis: a prospective comparative study of three quantitative assays.

OBJECTIVES: To assess the diagnostic reliability of a new quantitative D-dimer assay (VIDAS New) and an established quick test (Nycocard D-dimer assay) in the diagnosis of deep vein thrombosis (DVT) compared with ultrasonography. A third assay (Auto Dimer) became available during sample collection and has been included in the final assessment. The diagnostic performance of the Auto Dimer assay was evaluated on three different coagulation analysers. DESIGN: A clinical prospective study of patients admitted to hospital for evaluation of DVT. Setting. The admission ward at Aalborg Hospital. Subjects. A total of 113 outpatients with suspected DVT. Main outcome measures. Compression ultrasonography was used as the reference method for a diagnosis of DVT and compared with different D-dimer assays. The results were expressed as sensitivity, specificity, positive predictive value and negative predictive value (NPV). RESULTS: Deep vein thrombosis was established in 49 patients (43%). Two D-dimer assays (VIDAS New and Auto Dimer) showed sensitivities of 90 and 88%, specificities of 42 and 44%, and NPV's of 85 and 83%, respectively. The Nycocard D-dimer assay showed a sensitivity of 63%, specificity of 67% and NPV of 71%. CONCLUSIONS: The diagnostic performance of VIDAS New and the Auto Dimer D-dimer assays is almost identical, but this study suggests that neither of the D-dimer assays is suitable as the only screening method for DVT, in a situation with a high pretest probability of DVT. This call for a differential strategy that distinguishes between cases of low and high clinical probability using either a D-dimer test or ultrasonography. Abbreviations DVT, deep venous thrombosis, NPV, negative predictive value, PPV, positive predictive value

1-Deamino-8-D-arginine vasopressin lowers protein C activity in uremics.

The effect of 1-deamino-8-D-arginine vasopressin (DDAVP) on protein C was investigated in 10 uremics and 10 normal subjects. The protein C antigen was higher in the uremic patients than in the normal subjects. DDAVP had no influence on the level of protein C antigen. However, functional protein C in uremics was lower than in normals even before administration of DDAVP. Furthermore, there was a decrease in functional protein C in the uremics after administration of DDAVP. Further studies are needed to clarify the low functional protein C in uremics both before and during administration of DDAVP.

Antithrombin III and dietary intake of polyunsaturated fatty acids.

Immunoreactive antithrombin III and antithrombin III activity was found to be significantly higher in 81 Greenland Eskimos than in 50 Caucasian Danes. Sixteen Eskimos who had emigrated to Denmark had significantly lower immunoreactive antithrombin III levels than the Greenland Eskimos, though higher than the Danes. The immunoreactive antithrombin III increased significantly while the increase in antithrombin III activity was insignificant in 20 male Caucasian Danes upon 3 weeks supplementation of the diet with 10 ml daily of a cod liver oil concentrate. The high antithrombin III level in the Eskimos may at least partly be a consequence of a high dietary intake of polyunsaturated fatty acids. It may also play a role for the low incidence of thrombosis apparently found in Greenland Eskimos.

Alterations in plasma antithrombin III following total hip replacement and elective cholecystectomy.

Antithrombin III activity and immunoreactive antithrombin III was determined in 31 patients before elective surgery and 3 h, 1, 3 and 7 d after. The values fell about 10--20% from 3 h to 3 d, but had returned to preoperative levels by the seventh day. A fall to 40% was seen. The fall in activity was a little smaller than the fall in immunoreactive protein.

Familial functional antithrombin III deficiency.

A family with a tendency to thrombosis and decreased antithrombin III (AT III) activity in plasma, but normal immunoreactive AT III is reported. 7 members of the family had the AT III defect, 4 of whom have had thrombotic episodes. The importance of biological determination of AT III when studying patients with recurrent thrombotic episodes is emphasized.

Recurrent thrombosis in a patient with factor XII deficiency.

The case history of a patient with moderate factor XII deficiency and recurrent deep vein thrombosis is described. A decreased resting fibrinolytic capacity suggests that 'in vivo' Hageman factor acts mainly as a promotor of clot dissolution. It further indicates that the in vitro demonstration of factor XII as an activator for other biochemical pathways might be of minor importance in vivo, as alternative pathways for activation of these systems exist.

The complement system in uremia.

Plasma C1q, C1 esterase inactivator, C4, C3 and C3 proactivator were measured in 20 chronic uremic patients on maintenance hemodialysis, in 10 conservatively treated chronic uremic patients and in 20 healthy volunteers. There was no statistical significant difference between the patient groups in any of the measured complement components. The C1q, C1 esterase inactivator and C4 concentration were found to be the same in the patient and the control groups. The C3 and C3 proactivator levels were equally and significantly lower in both patient groups compared with the healthy volunteers.

C3 polymorphism in patients with chronic uremia.

The C3 polymorphism phenotypes were determined by high-voltage agarose gel electrophoresis in 83 patients with chronic uremia on maintenance hemodialysis. In 45 patients with chronic pyelonephritis, the frequency of C3F and C3FS was significantly lower than in 38 patients with chronic glomerulonephritis and in a large control group.

Complement-mediated reactions to diazepam with Cremophor as solvent (Stesolid MR).

Changes in complement reactions are described in two patients exhibiting adverse reactions to Stesolid MR (diazepam with Cremophor as solvent). The recorded frequency of adverse reactions to Althesin, propandid and Stesolid MR suggests that the common solvent Cremophor is responsible for the adverse reactions.