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What is the pituitary gland and what does it do?

The pituitary gland is the conductor of the endocrine orchestra. Find out what happens when your hormones get out of sync.

It may be small, but the pituitary gland is the master gland of the endocrine system. It signals endocrine glands all over the body to increase or decrease their hormone production.

What is the pituitary gland and what does it do?

The pituitary gland is a small pea-sized gland located in the base of the brain [1]. It is often referred to as the master gland as it controls the production of hormones in most of the endocrine glands in the body.

The pituitary gland has two lobes, the anterior lobe and the posterior lobe, which are connected to the hypothalamus gland by a stalk.

The anterior lobe of the pituitary gland is responsible for producing the hormones that signal other hormone glands to increase or decrease hormone production.

 

These hormones include:

  • Adrenocorticotrophic hormone (ACTH) -ACTH stimulates the adrenal glands to produce cortisol, a steroid hormone that influences many different processes around the body including metabolism and immune response. ACTH levels are highest in the morning and gradually decline during the day.
  • Follicle-stimulating hormone (FSH) -FSH is an important reproductive hormone. In women, it stimulates the growth of ovarian follicles (eggs) in the ovaries and in men, the testes to produce sperm. In women, FSH levels rise as the number of viable eggs declines with age. Elevated FSH is a marker for menopause in women.
  • Growth hormone (GH) -Growth hormone is produced in the anterior gland of the pituitary where it is released into the bloodstream. It acts on many cells in the body, working to stimulate growth and cell reproduction and repair. Growth hormone, also known as human growth hormone (HGH) rises in childhood and declines from middle age.
  • Luteinising hormone (LH) -LH is a gonadotrophic hormone, essential for the reproductive health of men and women. In men, it stimulates the Leydig cells in the testes to produce testosterone. In women, it plays a role in the menstrual cycle and preparing the body for pregnancy – stimulating the ovaries to produce oestradiol in the first half of the cycle and the corpus luteum to produce progesterone in the second half. A surge in LH triggers the ovary to release an egg (ovulation) midway through the menstrual cycle.
  • Melanocyte stimulating hormones (MSH) -MSH is the name for a group of hormones that have a range of functions, from stimulating the production of melanin in the skin (pigmentation) to controlling inflammation and appetite. It is produced in the pituitary gland as well as the skin and hypothalamus gland.
  • Prolactin (PRL) -Prolactin is the hormone that is responsible for lactation, the production of breast milk. It also has a role in men and women for sexual satisfaction, behaviour, and the regulation of immune function.
  • Thyroid-stimulating hormone (TSH) -TSH stimulates the thyroid gland to produce thyroid hormones that govern the body’s metabolic rate, influencing virtually every cell of the body.

 

The posterior lobe of the pituitary gland does not produce hormones. It acts as storage and release for oxytocin and anti-diuretic hormone (ADH), which are produced in the hypothalamus. As such, it acts as an extension of the hypothalamus gland.

 

What can go wrong with the pituitary gland?

As with the hypothalamus, injuries or trauma to the head can cause problems in pituitary function as can tumours in the brain which put pressure on the pituitary gland.

By far, the most common cause of a pituitary disorder is a tumour of the pituitary gland itself. The vast majority of pituitary tumours are benign (non-cancerous) and some do not have any effect on hormone production (non-functioning tumours).

However, some pituitary tumours can cause the over-production of one or more pituitary hormones, while others can cause the suppression of hormone production (hypopituitarism, or underactive pituitary gland).

Disorders of the pituitary gland include [2]:

  • Cushing’s disease (too much cortisol)
  • Prolactinoma (too much prolactin caused by a prolactin-producing tumour)
  • Acromegaly (too much growth hormone)
  • Growth hormone deficiency (growth hormone suppression)
  • Diabetes insipidus (suppression of anti-diuretic hormone affecting the kidney’s ability to retain water)

Hypopituitarism (an underactive pituitary gland) – causes, symptoms, treatment

Problems with your pituitary can affect its ability to produce one or more hormones. This can have wide-ranging implications for your health, depending on which hormones are affected.

Hypopituitarism can affect: 

  • Follicle-stimulating hormone (FSH) —egg and sperm production
  • Luteinising hormone (LH) —menstruation, testosterone production and fertility
  • Growth hormone (GH) —growth in children and a range of issues in adulthood
  • Thyroid-stimulating hormone (TSH) —maintenance of normal metabolism
  • Adrenocorticotrophic hormone (ACTH) —adrenal function
  • Prolactin (PRL) —production of breast milk

What are the symptoms of pituitary gland disorder?

The pituitary gland plays such a central role in orchestrating the production and release of many hormones throughout the body. It can affect one or more hormone systems.

The symptoms of a pituitary disorder can be wide-ranging. They can also be confused with other conditions and many pituitary disorders go undiagnosed.

Symptoms will vary according to whether the pituitary disorder is causing over or under-production of the affected hormone and which endocrine gland is ultimately affected.

Symptoms of a pituitary disorder can include [3]:

  • Loss of libido
  • Difficulty gaining muscle
  • Infertility
  • Irregular periods
  • Weight gain
  • Weight loss
  • Sensitivity to heat or cold
  • Hirsutism (excess hair)
  • Excessive thirst and frequent urination
  • Mood swings and depression
  • Constipation
  • Difficulties sleeping
  • Milky discharge from nipples (in both men and women)
  • Muscle and joint aches
  • Fatigue

This list is by no means exhaustive. You should make a note of any symptoms that apply to you so that your doctor can confirm or rule out a pituitary disorder.

How is a pituitary disorder diagnosed and treated?

A pituitary disorder is diagnosed through a combination of a physical examination (including an eye examination and brain imaging to detect tumours) and symptoms, as well as hormone blood tests that can detect unusual levels of hormones in the blood.

A pituitary disorder is often picked up as an incidental finding on a test, especially if you are not experiencing symptoms.

Many pituitary tumours do not require treatment. However, if the tumour is causing a significant hormone disturbance or compressing important parts of the brain, surgery or radiation therapy may be required to remove it.

Hormone replacement therapy or hormone-blocking treatments can be helpful to normalise the under-production or over-production of hormones.

Where next?

Learn more about other glands and their role in hormone health:

  1. The hypothalamus
  2. The adrenals
  3. The gonads
  4. The thyroid and parathyroid glands
  5. The pancreas, pineal and thymus
  6. Hormone blood test buying guide

References

  1. Pituitary.org.uk. 2022. What is the pituitary gland? | The Pituitary Foundation. [online] Available at: <https://www.pituitary.org.uk/information/what-is-the-pituitary-gland/> [Accessed 12 July 2022].
  2. Ohsu.edu. 2022. Understanding Pituitary Disorders | Brain Institute | OHSU. [online] Available at: <https://www.ohsu.edu/brain-institute/understanding-pituitary-disorders> [Accessed 12 July 2022].
  3. Pituitary.org.uk. 2022. What are pituitary symptoms? | The Pituitary Foundation. [online] Available at: <https://www.pituitary.org.uk/information/symptoms,-diagnosis-and-tests/symptoms/> [Accessed 12 July 2022].