Final answer:
Shortness of breath is a symptom that could necessitate hematocrit testing, particularly in diagnosing anemia or polycythemia. Hematocrit testing measures the volume percentage of RBCs in the blood, helping to diagnose various blood disorders.
Step-by-step explanation:
A symptom that may call for hematocrit testing is B. Shortness of breath. Shortness of breath can be a symptom of anemia, a condition where there are not enough red blood cells (RBCs) to carry adequate oxygen to the body's tissues. Lack of oxygen can make a person feel fatigued, weak, or short of breath. Anemia can be caused by excessive bleeding, inherited disorders, nutritional deficiencies, or diseases that affect the production of RBCs. Since hematocrit testing measures the proportion of blood volume that is occupied by red blood cells, it can be useful in diagnosing anemias as well as conditions such as polycythemia, where there is an elevated RBC count. Conditions like polycythemia vera and myelofibrosis can also lead to an enlarged spleen and may significantly affect the blood's ability to function properly. Furthermore, disturbed vision may be a secondary symptom associated with conditions like anemia, where reduced oxygen delivery to tissues can impair various body functions.