NHA Phlebotomy Certification Practice Exam

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Prepare for the NHA Phlebotomy Certification Exam. Learn with study guides and multiple choice questions. Each question offers detailed explanations. Achieve success on your certification test.

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Which of the following tubes must always be completely filled?

Gray.
Light blue.
Red.
Pink.

The correct answer is: Light blue.

The light blue tube must always be completely filled because it contains sodium citrate, which acts as an anticoagulant. This tube is primarily used for coagulation studies, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). The reason for needing the tube to be completely filled is to ensure the proper ratio of blood to anticoagulant. An inaccurate ratio could lead to erroneous test results, which could misrepresent the patient's coagulation status. In contrast, while the gray, red, and pink tubes have their own specific requirements and applications, they do not have the same critical needs for complete filling to guarantee accuracy in the tests performed. Therefore, the emphasis on the light blue tube's filling is essential for reliable hemostasis testing.