Final answer:
A requisition can be a hard copy or digital request for laboratory tests and is used in various medical situations such as diagnosis of hemolytic anemia or preparation for blood transfusions.
Step-by-step explanation:
A requisition is a form used to request a laboratory service, such as a blood test, and does not have to be a hard copy; it can also exist in digital format, especially in modern healthcare settings that use electronic health records (EHRs). In the context of the blood tests mentioned, requisitions would help specify the need for specific blood tests such as thyroid hormone levels, cross matching, or glucose levels to assist in diagnosing conditions like diabetes mellitus or determining treatment plans like blood transfusions.
For instance, in the case of potential hemolytic anemia, a requisition form would be used to order the necessary blood tests to identify antibodies attached to red blood cells. Similarly, before a blood transfusion, a requisition would specify the need for a blood type test to ensure compatibility between donor and receiver, except in urgent situations where O-negative blood, the universal donor type, may be used without cross-matching due to its general compatibility.