is decresed TSH result in hyperthyroidsm
Yes, decreased (or low) thyroid-stimulating hormone (TSH) levels are typically seen in hyperthyroidism. TSH is a hormone produced by the pituitary gland that stimulates the thyroid gland to produce thyroid hormones—primarily thyroxine (T4) and triiodothyronine (T3).
In hyperthyroidism, the thyroid gland is overactive and produces too much thyroid hormone. As a result, the elevated levels of circulating thyroid hormones feed back to the pituitary gland and inhibit the secretion of TSH. Hence, a low TSH level is indicative of an overactive thyroid.
However, a low TSH can also be caused by other factors, such as pituitary dysfunction (secondary hypothyroidism), so additional testing of free T4 and free T3 levels can help confirm the diagnosis of hyperthyroidism. Elevated levels of these hormones in the presence of low TSH typically confirm the diagnosis. Other tests and diagnostic procedures may be used to determine the cause of the hyperthyroidism, such as radioactive iodine uptake tests, thyroid scans, and ultrasound of the thyroid gland.