Thyroid nodules or tumors. Other autoimmune disorders. Your own observation of symptoms. Medical history and physical exam by a doctor. Laboratory blood studies.
Medication controls the problem in most patients.
This is a life-threatening emergency. Misdiagnosis as a psychiatric anxiety reaction. Allow 6 months of treatment for the condition to stabilize. Some forms may return to normal without treatment. If family and friends mention changes in your behavior or appearance, consult your doctor.