What is the endocrine system?
What and where is the pituitary gland?
What do these areas do?
Why is the pituitary gland so special?
What can go wrong with the pituitary gland?
How many hormones does the pituitary make?
What glands does the pituitary “talk” to?
Are there other endocrine glands in the body?
How would I know if my pituitary gland was not functioning correctly?
Can hormones be replaced if the body is not making enough?

What is the endocrine system?

The endocrine system is a collection of ductless glands throughout the body, that secrete hormones directly into the blood stream. There is no network of pipes that other body parts use to transport their secretions.

What and where is the pituitary gland?

The pituitary gland is a reddish brown, soft, oval pea-sized gland 1cm in size. The gland (a gland is a collection of special cells that make secretions called hormones) lies in the head, at the under side of the brain. The gland is connected to the brain by a stalk. The flattish areas of the brain that the stalk connects with is called the hypothalamus. When we talk about the pituitary gland we are thinking about the three areas, as they work together and each area is dependent on the other two areas. The pituitary gland sits in a depression of the sphenoid bone of the skull called the sella at the level of the bridge of the nose. If surgery is required the most common pathway to reach the pituitary gland is via the nose.

What do these three areas do?

These three areas together control hormones in the body. So what are hormones? Quite simply, hormones are messengers. “Hormone” comes from the Greek word meaning “to excite”. In effect we are talking about chemical messengers. The secretions that are made are hormones (a collection of chemicals) that are carried around the body, in the blood, and ‘excite” other body parts, or tissues, to do something. A bit like a supervisor instructing the workers!

Basically, hormones are carried in the blood stream. If levels become too low or too high the message is picked up by the hypothalamus, which makes hormones (chemical messengers) which pass through the stalk. The message is picked up by the pituitary gland, to make or send out hormones, which go to the “target” glands (the target or sites that the hormone messengers are aimed for). The target glands are then instructed to do more work, or to cut back, on their hormone output (put simply, like the switch on, switch off mechanism of your refrigerator).

Why is the pituitary gland so special?

So why do we hear so much about the pituitary gland? And why is the pituitary gland called the master gland? First let us look at the work of the pituitary gland. We know that the pituitary gland makes and stores hormones that influence other glands in the body. If things go wrong, it is usually the pituitary gland where the problem originates. The pituitary gland and the stalk are the areas that we can clearly see on special scanning. We can measure the hormones in the blood stream that the pituitary has made, or stored. If we can identify a shortage or over production of a hormone from the pituitary gland we can either:

• Replace the hormone that the body glands cannot make (because they have not received messages from the pituitary), or
• We can give hormones that ask the pituitary gland to send out fewer hormones itself, if it has become over active.

Other choices of treatment are that the pituitary gland can be operated on surgically and can also less commonly be treated with radiotherapy.

What can go wrong with the pituitary gland?

What can happen is the development of a tumour, or adenoma, of the pituitary gland. A tumour, or adenoma, of the pituitary gland is a benign growth or lump. Benign means limited, non cancerous. We know that sometimes the tumour, or adenoma, can become large, but it will not spread throughout the body as a cancer can sometimes do. A tumour , or adenoma, may be very small (micro adenoma) - less than 10 millimetres, or large (macro adenoma) - more than 10 millimetres. More rarely may be a bleed in the pituitary gland, or under certain conditions, the gland may swell. Both these conditions will put pressure on the pituitary gland.

How many hormones does the pituitary make?

• Six hormones from the front (anterior) part of the gland - TSH, LH, FSH, Prolactin, Growth hormone and ACTH.
• Two hormones from the back (posterior) part of the gland - ADH and Oxytocin.

What glands does the pituitary "talk" to?

First the anterior pituitary - the anterior pituitary makes and stores the following hormones:

• Thyroid stimulating (TSH) so that the thyroid gland can make thyroid hormone (T4) and tri-idothyronine (T3)
• Adrenocorticotrophic hormone (ACTH), so that the adrenal glands can then make cortisone.
• Leutinising hormone (LH) and
• Follicle stimulating hormone (FSH), so that the ovaries, (two glands in women) can make oestrogen and progesterone and the testes, (two glands in men) can make testosterone
• Growth hormone for growth of all the tissues of the body
• Prolactin to make breast milk.

Secondly the posterior pituitary gland - the posterior pituitary makes and stores the following hormones:

• Oxytocin to ask the uterus (womb) to contract during childbirth.
• Anti-diuretic hormone (ADH) which controls how much urine is passed.

Are there other Endocrine glands in the body?

Yes! Other glands in the body include the four parathyroid glands for calcium production and the pancreas gland for insulin production. These glands do not need the pituitary gland to give them messengers to make their hormones, but they are part of the endocrine system.

How would I know if my pituitary gland was not functioning correctly?

There are a variety of things which may happen. These may be headache, visual disturbance, feelings of being unwell, tiredness, lethargy, inability to cope, unexpected abnormal growth, sleep disturbance, discharge from the nipples, impotence, absence or disturbance of the menstrual cycle, skin and hair changes. The expression “we are slaves to our hormones” is one that people with an imbalance of the endocrine system can relate to very well, because usually more than one physical sign or symptom (feeling) may be found. Not everyone of course will get all these signs as symptoms, and some may be difficult to define. These signs and symptoms may occur because of the target organs not working effectively and not be the fault of the pituitary gland itself. Your endocrinologist (hormone specialist), after careful questioning of your symptoms, and a check for any body changes, may request special tests to diagnose if you have a problem with any part of your endocrine system.

Can hormones be replaced if the body is not making enough?

• Yes! Any hormone can be replaced by synthetically (laboratory) made medications. They may not all be taken as tablets. Creams, patches, implants and injections are used for some of the hormone administration.

This article updated:  May 2009