Final answer:
Andrea likely has anorexia nervosa, an eating disorder characterized by severe underweight due to malnutrition, which also correlates with her dehydration and very low bone mineral density.
Step-by-step explanation:
Based on the clinical tests that Andrea, a 22-year-old college student, underwent when rushed to the hospital after collapsing at the gym, she is likely suffering from anorexia nervosa. Her body mass index (BMI) of 16.8 is well below the normal range, indicating severe underweight. This eating disorder is known for causing extreme thinness due to malnutrition as a result of inadequate food intake, excessive exercise or a combination of both.
Furthermore, individuals dealing with anorexia nervosa often experience dehydration and are subject to very low bone mineral density among other health risks. These risks include but are not limited to heart failure, kidney failure, amenorrhea (which is the cessation of the menstrual period), reduced gonadal function, anxiety disorders, mood disorders, and an increased risk of substance abuse. Without professional intervention, anorexia nervosa could potentially lead to life-threatening complications.