Using incorrect concentrations. If your vitamin C standard solution is too concentrated or your iodine titration solution is too diluted, or your starch indicator solution is not between 0.5 to 1.0%, it may require much more than 50 mL of iodine solution to titrate the standard solution and/or orange juice.
The following summarizes some common causes of fatigue but is not meant to be comprehensive: Metabolic/endocrine: anemia; hypothyroidism; diabetes; electrolyte abnormalities; kidney disease; liver disease; Cushing's disease.
Anemia can be caused by iron deficiency, vitamin deficiency, chronic disease, bone marrow disease, autoimmune disorders and sickle cell anemia, among other causes. Anemia can be temporary or chronic, and its severity ranges from mild to marked. Cancer can cause extreme fatigue and weakness.