Final answer:
The lab value that most likely confirms a diagnosis of hyperthyroidism is decreased TSH levels.
Step-by-step explanation:
The lab value most likely to confirm a diagnosis of hyperthyroidism is 2) Decreased TSH levels. Hyperthyroidism is characterized by an overactive thyroid gland that produces excessive amounts of thyroid hormone. In response, the pituitary gland decreases the production of thyroid-stimulating hormone (TSH) to try to regulate the levels of thyroid hormone. Therefore, decreased TSH levels are often seen in individuals with hyperthyroidism.