After Collecting Several Evacuated Tubes from a Patient, the Phlebotomist

Multiple Choice

After collecting several evacuated tubes from a patient, the phlebotomist receives a pager message to go to the intensive care unit (ICU) immediately and draw several stats. Because of this page, he or she forgets to properly invert the tubes just collected. Which of the following tests is most likely to be affected by this action?

A) Activated partial thromboplastin time (APTT) in a sodium citrate tube
B) Glucose in a plain red top tube
C) Ionized calcium in a plain red top tube that remains sealed
D) CO₂ in a plain red top tube that remains sealed