What is the pituitary gland?

The pituitary gland sits at the base of the brain, in line with the top of the nose. It is quite small — about the size of a pea.

What does the pituitary gland do?

The pituitary gland is an important part of the hormonal system. It makes many different hormones. Some of these hormones have direct effects on the body, and others control the actions of other glands that produce hormones.

The pituitary is controlled in 2 ways: by signals from the part of the brain called the hypothalamus, and by sensing levels of other hormones in the body.

What hormones does the pituitary gland make?

The pituitary gland makes:

• growth hormone, which regulates growth
• thyroid stimulating hormone, which tells the thyroid gland to make thyroid hormones
• prolactin, which controls breast milk production
• adrenocorticotrophic hormone, which tells the adrenal glands to make hormones to control blood pressure, blood sugar levels and stress
• follicle stimulating hormone, which is involved in the reproductive system
• luteinising hormone, which is also involved in the reproductive system
• oxytocin, which is involved in childbirth and breastfeeding

Medical conditions related to the pituitary gland

The pituitary gland can become disturbed and make too much or too little of a hormone. It can also be the site of a tumour, which can cause problems by squashing the surrounding brain tissue. Most tumours in the pituitary gland are not cancerous and only cause problems when they change hormone levels or take up too much space.

Here are some of the more common pituitary conditions.

• Hyperprolactinaemia (too much prolactin in the blood). It can be caused by a tumour on the pituitary gland. A woman with hyperprolactinaemia might notice her periods becoming lighter or stopping, might have difficulty getting pregnant and may also start lactating (producing breast milk). A man with hyperprolactinaemia might have difficulty getting erections, develop swollen breasts and have less body hair.
• Growth hormone deficiency — this can be caused when the pituitary gland does not produce enough growth hormone, sometimes due to a tumour, damage to the pituitary or abnormal development of the pituitary. It can delay children’s growth and lead to a child being shorter in height than expected. In adults, the symptoms of growth hormone deficiency include fatigue, weak muscles and bones, excess weight, anxiety, mood problems or sleep problems.
• Hypopituitarism — this is a deficiency of all the pituitary hormones and causes many different symptoms.

Rare pituitary conditions include:

• gigantism — where a person grows very tall
• acromegaly — where a person’s hands, feet and jaw enlarge
• Cushing’s syndrome — where the body creates too many steroid hormones

More information

You can read more about possible disorders of the pituitary gland on the Australian Pituitary Foundation website or Hormones Australia website.

Learn more about the endocrine system and the different hormones released by the endocrine glands.