What is the pituitary gland?

The Pituitary Gland is sometimes known as the “Master Gland”. It receives signals from deeper areas in the brain such as the hypothalamus and in turn makes its own signals / hormones to travel to target tissues in the body. The hormones of the pituitary gland are:

• Growth hormone – stimulates growth in children and promotes health in adults
• Thyroid stimulating hormone – stimulates the thyroid gland to produce thyroid hormones
• Prolactin – only of consequence in women where it stimulates lactation
• Fertility hormones – Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) involved in the reproductive cycle in both men and women
• Adrenocorticotropic hormone (ACTH) – stimulates the adrenal glands
• Antidiuretic hormone – helps control how much fluid is in your body

Types of disorders of the pituitary gland

Disorders of the pituitary gland occur when there is too little or too much of one of the pituitary hormones produced. Examples of pituitary disorders are:

Growth hormone deficiency

Too little growth hormone in children can result in growth delay and short stature. In adults it is associated with metabolic problems such as central weight gain and can cause fatigue.

Growth hormone excess

This results in stimulation of tissues to grow. In children this can lead to increased final height or gigantism. In adults, where growth plates are fused, this can lead to tissue overgrowth that results in enlargement of hands, feet and jaw, as well as diabetes.

Prolactin excess (hyperprolactinemia)

Prolactin stimulates the breast to make breast milk. This is normal following pregnancy, but outside pregnancy this can lead to troublesome breast discharge in both men and women. Further, excess prolactin can suppress the normal fertility hormones. In women this can cause interruption of the menstrual cycle and reduce fertility. In men this can result in reduced libido.
The excess prolactin can be caused by a small growth on the pituitary. Your endocrinologist will investigate this with an MRI.

Cortisol excess (Cushing’s disease)

When the pituitary gland makes excess ACTH, this stimulates the adrenal gland to make cortisol; an excess of which can cause; increased blood pressure, diabetes and osteoporosis.

Cortisol deficiency

When the pituitary gland fails to make ACTH, the adrenal gland cannot produce cortisol and hypoadrenalism (adrenal insufficiency) results. This can be life threatening and is very important to identify. Most patients will present with nausea and fatigue and cortisol testing will aid in diagnosis. Your endocrinologist will then arrange an appropriate replacement cortisol for you.

How are pituitary disorders diagnosed?

Your endocrinologist will perform the appropriate hormone tests at various times of the day to demonstrate hormonal excess or deficiency. An MRI is usually required to ensure that there is no structural abnormality of the pituitary gland.