Prothrombin time protein

Table 32-3 summarizes laboratory results obtained on patients with three different causes of jaundice—hemolytic anemia (a prehepatic cause), hepatitis (a hepatic cause), and obstruction of the common bile duct (a posthepatic cause). Laboratory tests on blood (evaluation of the possibihty of a hemolytic anemia and measurement of prothrombin time) and on semm (eg, electrophoresis of proteins activities of the enzymes ALT, AST, and alkahne phosphatase) are also important in helping to distinguish between prehepatic, hepatic, and posthepatic causes of jaundice. 

CBC, complete blood cell count EEG, electroencephalogram NSAIDs, nonsteroidal antiinflammatory drugs O2, oxygen PPF, plasma protein fraction PT, prothrombin time TIPS, transjugular intrahepatic portosystemic shunt. 

Oral contraceptives have also been reported to produce increases in sulfobromophthalein retention and other liver function tests, as well as in prothrombin time, clotting factors VII, VIII, IX, serum thyroxine, and protein-bound iodine (B8). In a group of 48 women the mean cholesterol value was 206 41 mg/100 ml while they were receiving a variety of oral contraceptives and 179 28 mg/100 ml when they were not receiving the drugs (W19). 

Vitamin K status can be assessed by a functional test, called the "prothrombin time test," which involves measuring the lime required to form a blood clot. The test is performed as follows. A blood sample is withdrawn from a subject and immediately mixed with citric acid. Citric acid is a chelator, which means that it can form a tight complex with ions, such as calcium ions. The chelator prevents the interaction of calcium ions with the blood-clotting proteins and thus prevents these proteins from forming a blood clot in the sample. Calcium ions, it should be noted, are required for supporting the activity of several blood clotting proteins. The "citrated blood" is placed in a machine called a fibrometer. The fibrometer is used to detect increases in the viscosity of the blood over a period. 

Oral anticoagulation may cause warfarin embryopathy by inhibiting post-translational carboxylation of proteins needed in the normal ossification process. Intensity of treatment appears to be of importance, since there were no cases of warfarin embryopathy in 44 consecutive children of 42 mothers exposed in the first trimester, but who had prothrombin times prolonged by 40-60% (83,84). Experiments in rats in which highly intensive long-term... 

Cefoperazone 1-2giVq.12hr 20% No renai adjustment required. Dispiaced from protein by biiirubin may proiong prothrombin time reduce dose by 50% in patients with jaundice 1 g after dialysis NC NC... 

Although ketoprofen is highly bound to plasma proteins, one recent study indicated that it did not alter the coagulation cascade parameters or prothrombin time in humans treated concurrently... 

The liver synthesizes fibrinogen factors V, VIII, XI, and XII, and the vitamin K-dependent factors II, VII, IX, and X. Furthermore the liver plays an important role in platelet growth and function. The vitamin K-dependent proteins contain y-carboxy-glutamic acid. Vitamin K is necessary for the carboxylation of these proteins, which facilitate the conversion of prothrombin to thrombin. Patients with severe hepatocellular disease have decreased synthesis of the vitamin K-dependent clotting factors, especially factor VII. Furthermore, patients with cholestatic disease have decreased bile salt secretion, which is necessary for the absorption of vitamin K, leading to failure of activation of factors II, VII, IX, and X. In these patients, unlike those with hepatocellular disease, the prothrombin time can be corrected with an injection of vitamin K. 

The physiological expression of oral anticoagulant action is an increase in the time required for clotting in the prothrombin time assay. The slowing of all of the reactions that lead to the formation of thrombin is the direct result of the reduced concentrations of the vitamin K-related proteins in the reaction complexes on the membrane surface. The effects of oral anticoagulant blockage on the carboxylation reaction are common to all vitamin K-related proteins. 

Bilirubin concentrations and serum enzyme elevations give a static picture of the liver s condition and are not good indicators of hepatic function. Clinically available tests to predict hepatic function include measurement of serum proteins (albumin or transferrin). As a hepatic function decreases, serum protein concentrations in the body decrease at a rate determined by each protein s own elimination rate. Overhydration and starvation can also decrease serum protein concentrations. Changes in the prothrombin time often occur earlier than the changes in albumin or transferrin. The response of the prothrombin... 

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