What causes acromegaly?

What is the pituitary gland and what does it do?

The pituitary gland is a very small, pea sized gland; that lies in a small pocket of bone at the base of the brain, just behind your nose and between your ears.

Despite its small size, the pituitary gland plays a key role in the body’s hormonal or endocrine system by controlling the production and release of many different hormones throughout the body. These hormones are involved in your growth, sexual development and reproductive function, metabolism and response to stress.

The pituitary gland also controls the function of the thyroid and adrenal glands, with effects on metabolism, energy levels and the balance of salt and water in the body.

What is growth hormone and why is it important?

Growth hormone, which is also known as somatotropin, is a hormone produced by the pituitary gland throughout your life.

Growth hormone is secreted in short bursts or pulses, particularly during sleep.

In children, growth hormone is essential for skeletal growth.  In adults, it is important in maintaining energy levels, and keeping body tissues, such as muscle and bone, healthy.

When the pituitary gland releases growth hormone into the bloodstream, this triggers the liver to produce another hormone called insulin-like growth factor 1 (IGF-1). IGF-1 is the hormone that actually causes tissue growth.

Why does the pituitary over produce growth hormone?

The overproduction of growth hormone is usually caused by a benign (or non-cancerous) tumour (called an adenoma) within the pituitary gland.

Adenomas that produce growth hormone are the third commonest type of pituitary tumour after prolactinomas and non-functioning pituitary adenomas.

Some tumors grow slowly, and symptoms of too much growth hormone may not be noticed for many years.  Other tumors may grow rapidly.

What happens when there is too much growth hormone?

In adults, a long-standing excess of growth hormone causes growth of soft tissues, bone and cartilage, mainly at the hands, feet, forehead and jaw. It can also cause water retention.

Internal organs, such as the heart, can also grow in size, which may lead to heart disease if not recognised and treated.

Other possible complications of too much growth hormone are diabetes mellitus, joint problems, sleep problems (sleep apnoea syndrome) and carpal tunnel syndrome.