A prothrombin time, collected in sodium citrate, is received in the lab at 10:30am and remains on the counter until testing is performed at 3:30pm. What effect will this have on the results

Prothrombin time will be prolonged due to deterioration of factor V.

Explanation:

Prothrombin time (PT) assess the function of the blood clotting factors which include – vitamin K and factors I, II V, VII and X.

The PT will be longer than the standardized international normalized ratio (INR) if under any blood-thinning medications, absence or deterioration of blood clotting factors, or any inhibitors which inhibit the clotting factors.

While conducting a PT test, the blood sample is taken in a small test tube containing sodium citrate. The sodium citrate is an anticoagulant which will prevent coagulation.

The sample tube should be filled with the blood collected and the tube should also be inverted frequently to prevent any coagulation. The specimen collecting tube with sodium citrate is usually marked with a light blue color.  

Sodium citrate is used as the anticoagulant because it keeps the specimen stable with the help of its calcium chelating properties. However, at room temperature the specimen can be stable for about four hours.

Prolonged h and hours will deteriorate the coagulation factor V because the pH of the citrate solution is high mostly above 8.0 and hence prolonging the specimen in it will deteriorate the labile factor V  

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

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