Hyperthyroidism
Table:
Hyperthyroidism
Other names	Overactive thyroid, hyperthyreosis

Triiodothyronine (T3, pictured) and thyroxine (T4) are both forms of thyroid hormone.
Specialty	Endocrinology
Symptoms	Irritability, muscle weakness, sleeping problems, fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, weight loss[1]
Complications	Thyroid storm[2]
Usual onset	20–50 years old[2]
Causes	Graves' disease, multinodular goiter, toxic adenoma, inflammation of the thyroid, eating too much iodine, too much synthetic thyroid hormone[1][2]
Diagnostic method	Based on symptoms and confirmed by blood tests[1]
Treatment	Radioiodine therapy, medications, thyroid surgery[1]
Medication	Beta blockers, methimazole[1]
Frequency	1.2% (USA)[3]

Looking at the table, state whether the hypothesis is entailed, neutral, or refuted. Return the result as JSON: {"answer": "YOUR ANSWER"}.

Statement: Hyperthyroidism has no known cause.

answer: refuted