Thyroid Test is a series of blood tests used to measure how well your thyroid gland is functioning. Available tests include T3, T3RU, T4, TSH. The Thyroid gland is located below Adam’s apple in the neck and it secretes hormones. Thyroid is responsible for regulating mineral level in our blood. The main job of thyroid is to take iodine from the blood and combine it with amino acid. The purpose to perform thyroid test is to diagnose the cause of an underactive thyroid (hypothyroidism) or an overactive thyroid (hyperthyroidism) gland. Abnormal thyroid functioning is quite normal as it is found in two to three percent of the population. Normal range of TSH for an adult is 0.4-0.5 mu/ml.