The Thyroid, an endocrine gland, is called the "master regulator".  It is located in the neck below the Adams apple. 

Symptoms include; fatigue, weight gain, dry skin, hair loss, brittle nails, constipation and depression.  Regulated by the Pituitary and the Hypothalamus in the brain and the hormones metabolized in the liver.  The adrenal glands will also need to be evaluated since they too have a large effect on the thyroid's function and can mimic the thyroid symptoms.  These are all considered when testing.  Treatments depend on multiple factors and there is not one method of treatment for a patient.  Radiation, Herbicides, Houshold products, cosmetics, nail polish, soaps, glues, perfumes and bottled water all can contain these chemicals.  These will all be discussed with your appointment.