What is the pituitary gland and what does it do?

It may be small, but the pituitary gland is often referred to as the master gland of the endocrine system. It signals endocrine glands all over your body to increase or decrease their hormone production, regulating many important functions and processes.

In this article, we cover:

• What is the pituitary gland and what does it do?
• Where is the pituitary gland located?
• What hormones does the pituitary gland produce?
• What can go wrong with the pituitary gland?
• Tips for keeping your pituitary healthy

What is the pituitary gland and what does it do?
 

The pituitary gland is a small, pea-sized gland. It’s part of the endocrine system of glands that secrete hormones to regulate many important processes in your body, like growth and reproduction.

Some of the hormones produced by the pituitary gland have a direct effect on your body. Others control the actions of other endocrine glands, and that’s why the pituitary is often referred to as the master gland of the endocrine system.

The pituitary has two lobes — the anterior and posterior lobe. The anterior lobe makes hormones that signal other endocrine glands to increase or decrease hormone production.

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

Where is the pituitary gland located?
 

The pituitary gland is situated at the base of the brain. It sits directly below the hypothalamus — another important endocrine gland that initiates actions in the pituitary.

What hormones does the pituitary gland produce?
 

Hormones made by the pituitary gland include:

• Adrenocorticotropic hormone (ACTH) — ACTH stimulates the adrenal glands to produce cortisol and other hormones. Cortisol is a steroid hormone that influences many different processes in the body — it plays a vital role in metabolism, reducing inflammation, and how we manage stress. ACTH levels are usually 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, it stimulates the testes to produce sperm. FSH levels rise in women as their number of viable eggs declines with age. Therefore, elevated FSH levels can be an indicator that a woman is menopausal.

• Growth hormone (GH) — growth hormone acts on many cells in the body, stimulating growth, and cell reproduction and repair. Levels of growth hormone, also known as human growth hormone (HGH), peak in puberty and decline from middle age [1].

• 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 who have periods, LH plays a role in the menstrual cycle and preparing the body for pregnancy. LH stimulates the ovaries to produce oestradiol in the first half of the menstrual 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 are a group of hormones with a range of functions — from stimulating the production of melanin in the skin (pigmentation) to controlling inflammation and appetite. They’re produced in the pituitary gland as well as in the skin and hypothalamus gland.

• Prolactin (PRL) — in women, prolactin stimulates breast development and breast milk production (lactation). It also plays a role in sexual satisfaction and the regulation of immune function.

• Thyroid-stimulating hormone (TSH) — TSH stimulates the thyroid gland to produce and release thyroid hormones that govern metabolic rate, influencing virtually every cell in the body.

What can go wrong with the pituitary gland?
 

Several conditions can affect pituitary gland function. Most are caused by tumours of the pituitary gland. Tumours can interfere with the release of pituitary hormones, causing over- or underproduction. They can also press against other areas of the brain causing headaches or vision problems.

Most pituitary gland tumours are benign, or non-cancerous (adenomas), and some have no effect on hormone production (non-functioning tumours).

Other causes of pituitary gland health problems include:

• Brain injury/trauma
• Brain surgery
• Brain tumours, which put pressure on the pituitary gland

Disorders of the pituitary gland include [2]:

• Acromegaly: overproduction of growth hormone, which can lead to excessive growth, particularly of the hands and feet.
• Cushing’s disease: the pituitary releases too much ACTH, which leads to overproduction of cortisol. Symptoms include weight gain, high blood pressure, and weakness.
• Diabetes insipidus: this condition can be the result of a problem with the release of anti-diuretic hormone (ADH). It can cause people to pass large amounts of heavily diluted urine and feel excessively thirsty.
• Growth hormone deficiency (GHD): a rare, treatable condition caused by insufficient amounts of growth hormone. It can cause short stature (height) in children and metabolic issues in adults.
• Hypopituitarism: an underactive pituitary can produce little or none of one or more of its hormones. This can have wide-ranging effects on your health, depending on which hormones are affected. For example, the symptoms of too little/no TSH include weight gain and fatigue. These symptoms are like those of hypothyroidism (an underactive thyroid), as TSH stimulates your thyroid to produce its own hormones.
• Prolactinoma: too much prolactin is released, which can lead to infertility and decreased sex drive.

What are the symptoms of pituitary gland disorder?

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

Symptoms vary according to whether the pituitary disorder is causing over- or underproduction of the affected hormone, and which endocrine gland is affected.

Symptoms of a pituitary disorder include [3]:

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

This list is not exhaustive. You should make a note of any symptoms you experience to help your doctor confirm or rule out a pituitary disorder.

How is a pituitary disorder diagnosed and treated?

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

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

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

Hormone replacement therapy (HRT) or hormone-blocking treatments can help to normalise the under- or overproduction of hormones.
 

Tips for keeping your pituitary healthy
 

There are steps you can take to protect your pituitary. Although they may not prevent a pituitary disorder, they can help improve your overall health.

Ways to keep your pituitary gland healthy:

• Eat a healthy, balanced diet: your diet can affect your hormone levels and your overall health. A hormone-friendly diet focuses on healthy fats and protein, and plenty of fruit and vegetables, while avoiding ultra-processed foods.
• Manage your stress levels: chronic (long-term) stress can play havoc with your hormone balance and increase your cortisol level. Getting regular exercise and meditation are great ways to reduce your stress levels.
   

What are the main endocrine glands?
 

In addition to the pituitary, other endocrine glands that help keep your hormones in a healthy balance include:

• The hypothalamus
• The adrenals
• The gonads (ovaries and testes)
• The thyroid and parathyroid glands
• The pancreas
• The pineal
• The thymus

Find out more about hormones and the system that governs them in our Hormone Health Hub.

References

1. Garcia, J.M., Merriam, G.R., Kargi, and A.Y. (2019) Growth Hormone in Ageing. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279163/ (Accessed: 05 August 2024).
2. Ohsu.edu (2022) Understanding Pituitary Disorders | Brain Institute | OHSU. [online] Available at: <https://www.ohsu.edu/brain-institute/understanding-pituitary-disorders> (Accessed: 05 August 2024).
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 05 August 2024).