Pituitary gland

The pituitary gland is a small pea-sized gland that plays a major role in regulating vital body functions and general wellbeing. It is referred to as the body’s ‘master gland’ because it controls the activity of most other hormone-secreting glands.

Alternative names

Hypophysis.

Where is my pituitary gland?

The pituitary gland is a pea-sized gland.  It sits in thesella turcica (‘Turkish saddle’), a bony hollow in the base of the skull, underneath the brain and behind the bridge of the nose. Although the pituitary gland looks like one gland, it actually has two distinct parts, the anterior pituitary gland and the posterior pituitary gland. The gland is attached to the hypothalamus, the part of the brain that controls its activity. The anterior part of the pituitary gland consists of gland cells which are connected to the brain by very short blood vessels. The posterior pituitary gland is actually part of the brain and it secretes hormones directly into the bloodstream under the command of the brain.

What does my pituitary gland do?

The pituitary gland is called the ‘master gland’ as the hormones it produces control so many different processes in the body. It senses the body’s needs and sends signals to different organs and glands throughout the body to regulate their function and maintain an appropriate environment. It secretes a variety of hormones into the bloodstream which act as messengers to transmit information from the pituitary gland to distant cells, regulating their activity. For example, the pituitary gland produces prolactinwhich acts on the breasts to induce milk production. The pituitary gland also secretes hormones that act on the adrenal glands, thyroid gland, ovaries and testes, which in turn produce other hormones. Through production of its hormones, the pituitary gland controls metabolism, growth, sexual maturation, reproduction, blood pressure and many other vital physical functions and processes.

What hormones does my pituitary gland produce?

The anterior pituitary gland produces the following hormones and releases them into the bloodstream:

• Adrenocorticotropic hormone which stimulates the adrenal glands to secrete steroid hormones, principally cortisol
• Growth hormone which regulates growth, metabolism and body composition
• Luteinising hormone and follicle stimulating hormone, also known as gonadotrophins. They act on the ovaries or testes to stimulate sex hormone production and egg and sperm maturity.
• Prolactin which stimulates milk production
• Thyroid stimulating hormone which stimulates the thyroid gland to secrete thyroid hormones.

There are also some hormones which are produced by the hypothalamus and then stored in the posterior pituitary gland prior to being released into the bloodstream. These are:

• Anti-diuretic hormone which controls water balance and blood pressure. It is made by the hypothalamus but is stored in the posterior pituitary gland prior to being released into the bloodstream.
• Oxytocin which stimulates uterine contractions during labour and milk secretion during breastfeeding. It is made by the hypothalamus but is stored in the posterior pituitary gland prior to being released into the bloodstream.

Each of these hormones is made by a separate type of cell within the pituitary gland, except for follicle stimulating hormone and luteinising hormone which are made together by the same cell.

What could go wrong with my pituitary gland?

The pituitary gland is an important gland in the body and the hormones it produces carry out varied tasks and regulate the function of many other organs. This means that the symptoms experienced when the pituitary gland stops working correctly can be varied depending on which hormone is affected.

Conditions which affect the pituitary gland directly can be divided into three main categories:

1. Conditions that cause the pituitary gland to produce too much of one or more hormone(s). Examples include acromegaly, Cushing’s disease and prolactinoma.
2. Conditions that cause the pituitary gland to produce too little of one or more hormone(s). Examples include adult growth hormone deficiency, diabetes insipidus or hypopituitarism.
3. Conditions that alter the size and/or shape of the pituitary gland. Examples include empty sella syndrome.

A cell type may divide and then form a small benign lump known as a tumour, and the patient may then suffer from the effects of too much of the hormone the cell produces. If the tumour grows very large, even though still benign, it may squash the surrounding cells and stop them working (hypopituitarism), or push upwards and interfere with vision – a visual field defect. Very occasionally, the tumour may expand sideways and cause double vision as it affects the nerves which control eye movements. It should be emphasised that even when these tumours are large, they usually remain quite benign and very rarely spread to other parts of the body.