Thyroid-stimulating hormone (TSH) blood test is used to check for thyroid gland problems. TSH is produced when the hypothalamus releases a substance called thyrotropin-releasing hormone (TRH). TRH then triggers the pituitary gland to release TSH.
TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4). T3 and T4 help control your body's metabolism.Triiodothyronine (T3) and thyroxine (T4) are needed for normal growth of the brain, especially during the first 3 years of life. A baby whose thyroid gland does not make enough thyroid hormone (congenital hypothyroidism) may, in severe cases, be mentally retarded. Older children also need thyroid hormones to grow and develop normally. This test may be done at the same time as tests to measure T3 and T4.
An underactive thryoid gland (hypothyroidism) can cause symptoms such as weight gain, tiredness, dry skin, constipation, a feeling of being too cold, or frequent menstrual periods. And overactive thyroid (hyperthyroidism) can cause these types of symptoms: weight loss, rapid heart rate, nervousness, diarrhea, feeling too hot, or irregular menstrual periods.
