What will be the effect of the following on clotting time:
a. Hemolyzed specimen
b. Effect of glass tubes
The correct answer and explanation is :
Effect of Hemolyzed Specimen on Clotting Time:
When a blood specimen becomes hemolyzed, meaning the red blood cells rupture and release their contents into the plasma, it can significantly affect the clotting time. Hemolysis can interfere with the clotting cascade in several ways, leading to prolonged clotting times. Hemoglobin, potassium, and other intracellular components from lysed red blood cells can alter the plasma environment, impairing the function of clotting factors. Specifically, hemoglobin can act as a procoagulant or could bind to clotting factors, reducing their availability for clot formation. The presence of these hemolysis byproducts may also interfere with laboratory testing, especially in coagulopathy assessments.
Additionally, hemolysis may cause the breakdown of platelets, further complicating the clotting process. The activation of various enzymes due to cell membrane disruption can also contribute to coagulation abnormalities, which can manifest as extended clotting times when measured. Therefore, a hemolyzed specimen is often deemed unsuitable for clotting tests and may lead to inaccurate results.
Effect of Glass Tubes on Clotting Time:
Glass tubes can also influence clotting time, but in a different way compared to hemolyzed specimens. Glass surfaces have a procoagulant effect because they promote the activation of the intrinsic pathway of coagulation. When blood is collected in a glass tube, it comes into contact with the glass surface, which activates factor XII of the intrinsic pathway. This leads to a more rapid formation of fibrin clots, thus shortening the clotting time.
However, it’s important to note that the effect of glass tubes may vary depending on the specific blood test being performed. For tests such as prothrombin time (PT) or activated partial thromboplastin time (aPTT), the activation of the intrinsic pathway may cause inconsistencies in the results. To mitigate this, laboratories often use plastic tubes, which are less likely to cause activation of the coagulation pathway, leading to more accurate clotting time measurements.