Production of thyroid-stimulating hormone (TSH) occurs in the anterior pituitary gland. TSH gets released by thyroid-releasing hormone (TRH) and is sent to the thyroid. TSH results in the thyroid then releasing thyroxine, which helps control physical maturation and growth in the human body. Thyroxine is also involved in regulating metabolism.
Hypothyroidism
According to the National Institutes of Health, thyroid gland inflammation results in damaged cells in and around they thyroid. These damaged cells cause a reduction in efficiency of the thyroid. With the thyroid not producing thyroxine, the pituitary gland releases an increased amount of thyroid-stimulating hormone.
Signs of hypothyroidism include constipation, depression, unexplained weight gain, fatigue, joint and muscle pain, dry skin and cold sensitivity.
Pituitary Gland Tumor
A tumor on the pituitary gland can cause uncontrollable cell growth in the pituitary gland. This uncontrolled growth can lead to an increased production in hormones that get released from the pituitary gland, including thyroid-stimulating hormone.
According to the Mayo Clinic, symptoms of a pituitary gland tumor have a wide range of effects. Headache, loss of vision, clear nasal drainage, nausea, seizures, fatigue, cold intolerance, constipation, low blood pressure, body hair loss, sexual dysfunction and weight change represent symptoms of a potential tumor.
Genetic Mutations
Cells in the thyroid gland have proteins embedded called thyroid-stimulating hormone receptors. Without these receptors, TSH is unable to bind to the receptor, which results in a decreased production of throxine. The resulting lack of thyroxine production and its release into the blood causes an increase in TSH levels in the blood. If the TSH does not bind to a receptor, it will not do its job, and will continually get sent to the thyroid.
Loss of Thyroid Gland
Whether due to a birth defect, or removal because of cancer, the lack of a thyroid gland may result in an increase in TSH. With no thyroid to send negative feedback signals back to the pituitary gland, the pituitary continually releases thyroid-stimulating hormone under the impression that more is needed. TSH suppression medications effectively control the over-release of TSH.
Loss of Pituitary Gland
With no pituitary gland, there is no TSH production. Hormone medications exist that give people without a pituitary gland the TSH needed. Without optimized medication, too much TSH may be administered at a time, increasing its levels in the blood.
Reasons for not having a pituitary gland include cancer and birth defects.
References
- "Biology: Concepts and Connections"; Neil Campbell, Lawrence Mitchell and Jane Reece; 2000
- National Institutes of Health: Hypothyroidism
- Mayo Clinic: Pituitary Tumors
