Pituitary gland - key questions answered

What is the pituitary gland?

Your pituitary gland (hypophysis) is a small, pea-sized organ in your body that releases hormones. Your pituitary gland is part of your endocrine system, a network made up of glands and organs. Your endocrine system controls the biological process your body needs to function.

The pituitary gland is a key part of your endocrine system

Your endocrine system is also sometimes called your ‘hormone system’ because it produces the hormones needed to regulate the many biological processes your body relies on.

The hormones produced by the endocrine system are chemical messengers that travel though your blood and enable your cells to talk to each other - telling one another what to do. Hormones are chemicals that play a role in the following processes:

• Growth and development
• Reproduction
• Metabolism
• Energy and blood sugar level regulation
• Mood
• Response to stress, trauma or injury
• Water and salt balance
• Pregnancy, labor and childbirth, and breastfeeding

Read our guide to female reproductive hormones here.

Your pituitary gland is just one of the glands that make up your endocrine system. See the table below for an overview of the parts of your endocrine system.

Endocrine system overview

Where is the pituitary gland located?

Your pituitary gland is located at the base of your brain below an area called the hypothalamus. Its position below the brain is pointed to by the pituitary gland’s other name - the hypophysis - which is from the Greek for ‘lying under’.

Your pituitary gland sits below your brian in a boney hollow in your sphenoid bone called the sella turcica (‘Turkish saddle’), which is located behind the bridge of your nose.

What are the parts of the pituitary gland?

Your pituitary gland has two main lobes or parts called the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis). There is also an intermediate zone of cells between the two lobes.

Your anterior pituitary is made from the same tissue as your throat (pharynx). It makes up about 80 percent of the overall size of your pituitary gland, which usually weighs between 0.02 and 0.03 oz (500 and 900 mg). Your posterior pituitary is an extension of your hypothalamus.

Your pituitary gland is connected to your hypothalamus by the pituitary stalk (infundibulum), which is a bundle of nerves and blood vessels. The pituitary gland and hypothalamus are parts of your neuroendocrine system.

What does the pituitary gland do?

The pituitary gland produces and releases hormones that control different processes in your body. It is often described as the ‘master gland’ because it influences so many processes.

The two main lobes of the pituitary gland - the anterior pituitary and posterior pituitary - have different functions and release different hormones.

The anterior pituitary produces and releases six hormones

The anterior pituitary is controlled by the hypothalamus and produces and releases six hormones including:

• Adrenocorticotropic hormone (ACTH)
  ACTH, which is also known as cortitrophin, stimulates the adrenal gland to produce:
  • Glucocorticoids such as cortisol. Glucocorticosteroids help maintain blood sugar levels during fasting, prepare the body for stress, prevent inflammation, suppress the immune system, maintain blood pressure and more.
  • Adrenal androgens such as testosterone and dehydroepiandrosterone (DHEA). Adrenal androgens play a role in precocious puberty and the production of body hair in females during puberty
  • Mineralocorticosteroids such as aldosterone. Aldosterone maintains your salt and water balance, which helps regulate blood pressure.
• Thyroid-stimulating hormone (TSH)
  TSH stimulates your thyroid gland to release thyroid hormones. Thyroid hormones control your metabolism or the way your body uses energy. Thyroid hormones help regulate your heart rate, breathing, nervous system, weight, muscles, body temperature and more.
• Luteinizing hormone (LH)
  LH is a gonadotropic hormone that helps control the function of your ovaries or testes. LH stimulates ovulation in females and the production of testosterone in males.
• Follicle-stimulating hormone (FSH)
  FSH is a gonadotropic hormone that stimulates the production of sperm in males and the production of estrogen by the ovaries in females. It also plays a role in regulating menstrual cycles.
• Prolactin
  Prolactin stimulates the production of breastmilk.
• Growth hormone
  Growth hormone is the main hormone that regulates growth and metabolism. It stimulates growth in children and helps maintain healthy bones, muscles and fat distribution in adults.

The posterior pituitary does not produce hormones, but stores and releases two hormones made by the hypothalamus

The two hormones stored and released by the posterior pituitary are:

• Vasopressin or antidiuretic hormone (ADH)
  ADH promotes the retention of water in the body and regulates the balance of water and sodium in your body.
• Oxytocin
  Oxytocin helps labor to progress in females because it signals the uterus to contract. It also aids the flow of breastmilk and bonding with the baby. Oxytocin helps move sperm in males.

A hormone is also produced in the cells in the intermediate zone of the pituitary gland

Melanocyte-stimulating hormone (MSH), a hormone that regulates the production of the skin pigment melanin, is produced by the cells in the intermediate zone of the pituitary gland.

What are pituitary disorders?

Pituitary gland disorders are rare and are usually the result of under- or over-production of hormones produced by the pituitary gland. Hypopituitarism is the name given to an underactive pituitary gland and hyperpituitarism is used to describe an overactive pituitary gland.

Hypopituitarism and hyperpituitarism are typically caused by:

• Pituitary adenomas, which are a type of tumor that is usually benign (non-cancerous) and slow growing. They are the most common pituitary gland disorder. Non-functioning (non-secretory) pituitary adenomas place pressure on the surrounding areas, which may result in headaches or loss of vision. Functioning (secretory) adenomas secrete hormones like the anterior pituitary and can produce a range of symptoms depending on the hormones they secrete.
• Damage to the pituitary, hypothalamus or pituitary stalk, which may be caused by a head injury, surgery, infection, certain medications and cancer treatments, blood loss, bleeding in or near the pituitary and other causes.
• Genetic conditions, such as familial isolated pituitary adenoma (FIPA) or multiple endocrine neoplasia, type I (MEN I).

Common pituitary gland disorders linked to hypopituitarism - lower-than-normal levels of pituitary hormones - include:

• Central or secondary adrenal insufficiency. If ACTH levels are too low then it can lead to an underactive adrenal gland.
• Growth hormone deficiency. Growth hormone deficiency can lead to poor growth and short stature in children and changes in body composition in adults.
• Central hypogonadism. Hypogonadism or low sex hormones can lead to a low sex drive and fertility issues. This can occur if the pituitary gland does not produce enough LH or FSH.
• Central hypothyroidism. Your thyroid gland can become underactive and release too little thyroid hormone if your pituitary gland doesn’t produce enough TSH.
• Central diabetes insipidus: If your pituitary gland does not release enough ADH it can cause diabetes insipidus. This can result in you not retaining enough water because you produce too much urine and pee alot.

Common pituitary gland disorders linked to hyperpituitarism - higher-than-normal levels of pituitary hormones - include:

• Acromegaly and gigantism. Acromegaly is caused by too much growth hormone in adults. It causes abnormal growth in adults, such as oversized hands, feet, lips and jaws. Gigantism can occur in children and adolescents who produce too much growth hormone and can cause them to grow very tall.
• Cushing’s disease. Cushing’s disease occurs when your pituitary gland makes too much ACTH, which causes your adrenal gland to make too much cortisol. One of the obvious symptoms of Cushing’s disease is rapid weight gain, particularly on the face, stomach and back of the neck.
• Hyperthyroidism. If too much TSH is produced by the pituitary gland it can cause your thyroid gland to become overactive and produce too much thyroid hormone. This is a rare cause of hyperthyroidism.
• Hyperprolactinemia. If too much prolactin is produced by the pituitary gland it causes hyperprolactinemia. Hyperprolactinemia can cause a milky discharge from your nipples and infertility.

Other disorders that affect the pituitary gland include:

• Craniopharyngioma
• Prolactinoma
• Empty sella syndrome
• Kallmann's syndrome
• Rathke's cleft cysts
• Familial MEN 1 (Wermer's syndrome)
• Wolfram syndrome
• Septo-optic dysplasia
• Sheehan's syndrome
• Lymphocytic hypophysitis
• Nelson's syndrome

What are the symptoms of pituitary disorders?

Symptoms of pituitary disorders can vary a lot and typically depend on the number of hormones affected or the extent of damage to the pituitary gland.

Symptoms of pituitary disorders include:

• Headaches
• Vision problems, including loss of peripheral vision
• Too much or too little growth
• Infertility
• Irregular menstrual cycle
• Weight loss or weight gain
• Anxiety and depression

Can I live without a pituitary gland?

Yes, you can survive without a pituitary gland, but you’ll need to take medication to replace the missing pituitary gland hormones.

Bottom line

Your pituitary gland produces, stores and releases hormones that control a wide variety of functions in your body. Pituitary gland disorders are rare, but can cause a range of symptoms.

Protecting yourself from head injuries and traumatic brain injuries by wearing a seatbelt, driving carefully, wearing a helmet when necessary and avoiding falls can help you avoid problems with your pituitary gland.

If you experience symptoms of a pituitary gland disorder and suspect your pituitary gland is malfunctioning in some way, consult your endocrinologist. Your endocrinologist can order blood tests or imaging tests, such as an MRI or CT scan, to help diagnose a pituitary gland disorder.