The Pituitary Gland

The pituitary gland hangs from a small stalk at the base of the brain and is surrounded by bone for protection. It is a peanut-shaped gland, which is about the size of a pea in humans. It is divided into two parts that produce different control hormones: the anterior pituitary and the posterior pituitary.

The pituitary is sometimes known as the 'master gland' of the endocrine system because its role is to accurately control the action of the other endocrine glands.

However, as has just been pointed out, it is the hypothalamus that is directing the pituitary gland. The pituitary gland is simply like a computer that is able to brilliantly control a number of other systems. The pituitary still needs to be controlled and programmed - it is the hypothalamus that has this controlling function over the pituitary gland.

The pituitary produces a wide range of controlling hormones. These include:

Anterior pituitary hormones:

  • GH (growth hormone).
  • TSH (thyroid stimulating hormone).
  • ACTH (adrenocorticotrophic hormone).
  • Beta-endorphin.
  • PL (prolactin).
  • LH (luteinising hormone).
  • FSH (follicle stimulating hormone).
  • Melanocyte-stimulating hormones.

Posterior pituitary hormones:

  • Oxytocin
  • ADH (antidiuretic hormone also known as vasopressin).

Hormones secreted from the pituitary gland help control the following body processes: blood pressure; temperature regulation; growth; endorphin to relieve pain and change mood; water balance in the body; metabolism; thyroid gland function; sex organ function; lactation in women; changes in pregnancy.

The main two pituitary hormones that most frequently concern thyroid patients are TSH (which stimulates the thyroid gland) and ACTH (which stimulates the adrenal glands).

The pituitary can suffer disease and damage and if someone had this type of condition then if the pituitary gland could not produce enough of its hormones then it would be referred to as 'hypopituitarism'. If too many hormones were being produced then it would be referred to as 'hyperpituitarism', which is sometimes caused by an adenoma (benign tumour). All of these types of conditions need to be correctly investigated, diagnosed and treated by appropriate medical specialists.

In the cases of hypopituitarism or hyperpituitarism then it is frequently the specific endocrine glands that are being either under-stimulated or over-stimulated that are first identified via laboratory testing and the symptoms that the patient is having. It can take a great deal of investigation on the part of an appropriately qualified medical specialist to determine that the pituitary is the cause of the problem(s). Treatment will depend on the nature of the specific pituitary issue.

The pituitary and hypothalamus can also suffer dysfunction or dysregulation and produce lower (or in rarely higher) levels of ACTH or TSH than they used to. This is known as hypothalamic-pituitary dysfunction, or just HP dysfunction. This can be when there is no damage or obvious disease present. Some researchers believe that this can be caused by long term stress. But it can be caused by other things like lower T3 levels within the pituitary. It is thought that HP dysfunction is the most common cause of hypocortisolism. 

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