TSH

The thyroid gland produces hormones that regulate or affect many bodily functions. Thyroid stimulating hormone (TSH) is the hormone which controls the thyroid gland function. An excess or deficiency of these hormones can affect energy levels, mood, and many functions. When the thyroid gland fails, due to primary disease of the thyroid, TSH levels increase. This condition is called primary hypothyroidism meaning low functioning of the thyroid. In contrast, when the thyroid gland is overactive and producing too much thyroid hormone, the TSH level decreases. This is called primary hyperthyroidism, meaning excessive functioning of the thyroid. Both hypothyroidism and hyperthyroidism can be detected by the TSH test.