Functional Medicine is a biology-based approach that aims at finding the underlying root cause of an illness. The focus is on the patient’s health as a whole and not just on treating the symptoms. The reason for that is that a symptom may be caused by a variety of causes and a cause can lead to multiple manifestations. 

For example, the low thyroid function may be caused because of some nutrient deficiencies which we call it a root cause of your thyroid problem. And correction of that deficiency often leads to fixing the problem.