ABSTRACT
CONTEXT: The results of studies among patients with antithrombin deficiency have suggested that the use of warfarin will increase the level of antithrombin. OBJECTIVE: To reevaluate the effect of warfarin on antithrombin levels using an automated amidolytic method in current use. DESIGN: Antithrombin levels were measured in patients who were receiving warfarin for atrial fibrillation and were compared with antithrombin levels in preoperative patients who had not received warfarin. RESULTS: Patients receiving warfarin had a mean antithrombin level of 100.40% (range, 81%-153%). Patients not receiving warfarin had a mean antithrombin level of 99.97% (range, 79%-120%). The Student t test was not significant for a difference between the mean antithrombin levels of the 2 populations. CONCLUSIONS: The use of warfarin does not increase the level of antithrombin in patients receiving the drug.
Subject(s)
Anticoagulants/therapeutic use , Antithrombin Proteins/metabolism , Warfarin/therapeutic use , Adult , Aged , Aged, 80 and over , Antithrombin Proteins/analysis , Antithrombin Proteins/deficiency , Artifacts , Atrial Fibrillation/blood , Atrial Fibrillation/drug therapy , Blood Chemical Analysis/methods , Blood Chemical Analysis/statistics & numerical data , Case-Control Studies , Female , Humans , Male , Middle AgedABSTRACT
BACKGROUND: Factor XIII deficiency is a rarely encountered bleeding disorder traditionally identified by clot dissolution in 5 molar urea (urea solubility test). METHODS: We report a patient with delayed post-surgical bleeding characteristic of factor XIII deficiency with a normal urea solubility test. RESULTS: Factor XIII deficiency was identified by an automated assay that measured factor XIII antigen. The patient was successfully treated with cryoprecipitate. CONCLUSIONS: Patients with excessive bleeding with normal screening tests should be tested for factor XIII using a sensitive assay procedure. The urea solubility assay for factor XIII should be discontinued due to its lack of sensitivity.
Subject(s)
Blood Coagulation Tests/methods , Blood Coagulation , Cardiac Surgical Procedures/adverse effects , Factor XIII Deficiency/diagnosis , Postoperative Hemorrhage/etiology , Urea , Aged, 80 and over , Factor XIII Deficiency/blood , Factor XIII Deficiency/complications , Humans , Male , Postoperative Hemorrhage/therapy , Predictive Value of Tests , Solubility , Treatment OutcomeABSTRACT
Background. Patients undergoing joint replacement remain at increased risk for venous thromboembolism (VTE) compared to other types of surgery, regardless of thromboprophylactic regimen. The pathophysiologic processes rendering this group of patients at risk for VTE are multifactorial. Procedure-specific and patient-specific exposures play a role in the postoperative development of VTE, including the development of anti-phospholipid antibodies (aPL). Methods. We measured three aPL (anti-cardiolipin, anti-ß(2) glycoprotein, and lupus anticoagulant) in 123 subjects undergoing total knee or hip arthroplasty to describe the presence of these antibodies preoperatively and to describe the rate of postoperative seroconversion among those people who were negative preoperatively. Postoperative antibodies were measured at day 7, 14, and 21. Results. The prevalence of aPL antibodies in the preoperative period was 44%, positive subjects were more likely to be smokers (P = 0.05) and were less likely to have undergone a previous arthroplasty procedure (P = 0.002). Subjects seroconverted in a 21 day postoperative period at a rate of 79%. Conclusions. These pilot data suggest that the prevalence of aPL in this population both preoperatively and postoperatively is higher than previously expected. Further studies are needed to describe aPL in a larger population and to establish their clinical significance in populations undergoing joint replacement surgeries.
ABSTRACT
An assay for fondaparinux (Arixtra) is described based on a modified commercial assay for heparin. The assay is automated on a Dade Behring BCS XP (Siemens Healthcare Diagnostics, Deerfield, IL) and uses the inhibition of activated factor X to quantitate the drug. The assay was unaffected by platelet contamination or the presence of warfarin. The assay was affected by the antithrombin level, and the value obtained in the assay decreased significantly when the antithrombin level was less than 60%. The assay is, however, not specific for fondaparinux. Specimens containing unfractionated or low-molecular-weight heparin will yield results by this assay that will not be an accurate estimation of concentration.
Subject(s)
Autoanalysis/methods , Polysaccharides/blood , Antithrombins/pharmacology , Calibration , Clinical Laboratory Techniques , Factor Xa Inhibitors , Fondaparinux , Heparin , Heparin, Low-Molecular-Weight/pharmacology , Humans , Reproducibility of ResultsABSTRACT
A warfarin treated patient unexpectedly presented with an elevated international normalized ratio (INR). Repeat testing in two laboratories gave conflicting results. The chromogenic assay of factor X was used to determine the correct INR result. The patient had laboratory results consistent with a dysfibrinogenemia, which prevented detection of the endpoint with a photo-optical detection system. The chromogenic assay of factor X is recommended for monitoring patients on warfarin when the INR cannot be accurately determined due to interference with the fibrin endpoint in the INR.
