PITUITARY DISORDERS

What are pituitary disorders

• Pituitary disorders include any condition where the pituitary does not function normally. Commonly this is due to a pituitary tumor or pituitary failure from damage to the gland.

• One of the most common pituitary disorders is a pituitary tumour.

What is a pituitary tumor

• Pituitary tumors are growths on the pituitary gland.  

• While the pituitary gland is located near the brain, pituitary tumours are very different to brain tumours.

• These tumours typically affect adults.

• Pituitary tumours are also called pituitary adenomas.

• They are almost always not cancerous. Although they are usually benign it is important that they are managed correctly as the can cause serious problems from hormone abnormalities or if it grows and pushes on the eye nerve it can cause visual loss.

The problems caused by pituitary tumours fall into three main categories:

• Increased hormone production

• Reduced hormone production

• Enlarged gland size or a tumour within the pituitary gland

What are the types of pituitary tumour disorders

Pituitary tumors can be classified based upon their function or how active they are. The different groups of pituitary tumors include:

Secretory Tumours

Tumors can cause the pituitary to produce too much hormone. This overproduction can cause serious endocrine disturbances such as:

• Acromegaly (Excess growth hormone)

• Cushing's disease (Excess cortisol)

• Prolactinoma (Excess prolactin)

• Thyrotropinoma (Excess TSH hormone)

Non-secretory Tumours

In this condition the gland does not make excess hormones, but the main problem is the lump on the pituitary gland. An example of this is a non-functioning pituitary adenoma.

Pituitary Hypofunction

The pituitary normally regulates the other glands in the body. When the pituitary gland fails it make only small amounts or no hormone. When the pituitary is unable to make enough hormone to meet the requirements of the body it is called pituitary hypofunction.  It can be caused by anything that damages the pituitary. For example, large pituitary tumors can cause the pituitary to not make enough hormone.

Examples of pituitary hypofunction include:

• Diabetes insipidus (low antidiuretic hormone levels)

• Secondary hypothyroidism (low level of thyroid stimulating hormone from the pituitary)

• Secondary hypogonadism (low level of gonadal hormones LH & FSH from the pituitary)

• Secondary adrenal insufficiency (low level of ACTH hormone from the pituitary)

• Growth hormone deficiency (low level of growth hormone from the pituitary)

Enlarged Pituitary Gland

• The normal pituitary gland size varies depending on age, gender and pubertal stage.

• Growths on the pituitary can be divided into two groups based upon size. These are:

  • Pituitary macroadenomas - tumors larger than 1cm

  • Pituitary microadenomas - tumors smaller than 1cm

• Tumours can cause problems if they are large and interfere with normal function of the pituitary gland and/or nearby structures such as the optic/eye nerves.  They can cause compression of the normal pituitary gland leading to decreased or absent hormone production (hypopituitarism or pituitary failure).

• Large pituitary tumours can cause headaches, vision problems or other health effects.

What is the anatomy of pituitary gland

• The pituitary gland is a pea-sized organ, found at the base of the brain.

• The pituitary gland sits just below the eye nerve or optic chiasm. An abnormally enlarged gland can push on this eye nerve and cause  visual field loss.

What does the pituitary gland do

The pituitary gland produces many hormones that travel around the body, directing certain processes or stimulating other glands to produce other hormones.  

It is often referred to as the “master gland”. Without the pituitary, other glands do not work. The pituitary is the “boss” of the other glands in the body. It is analogous to a captain who steers a ship or a general who controls an army.

The pituitary gland makes or stores many hormone types including:

• Prolactin - Stimulates breast milk production

• Growth Hormone - Stimulates growth in childhood and healthy body composition, well-being, muscle mass and bone mass  in adults and fat distribution

• Adrenocorticotropin - Stimulates production of cortisol by the adrenal gland

• Thyroid-Stimulating Hormone - Stimulates the thyroid gland to produce thyroid hormones,

• Luteinizing Hormone - Stimulates testosterone production in men and ovulation in women

• Follicle-Stimulating Hormone - Promotes sperm production in men and stimulates the ovaries to produce estrogen and develop eggs in women.

• Antidiuretic Hormone - Regulates water balance in the body

• Oxytocin – Causes milk to flow from the breasts in breastfeeding women

Who is at risk of pituitary disorders

The key risk factor for pituitary tumors is genetics. Genetic conditions like Multiple Endocrine Neoplasia, can cause Pituitary Disease.

Pituitary tumors have few other known risk factors such as environmental or lifestyle-related risk factors. Some research suggests obesity may increase risk.

What are the causes of pituitary disorders

There are several direct causes of pituitary disorders these include:

• Pituitary tumours

  • Hypersecretion

  • Hyposecretion

• Medication

• Pituitary failure

  • Intracranial surgery

  • Radiation herapy

  • Injury or major head trauma.

  • Bleeding inside or close to the pituitary

  • Inflammation of the pituitary (hypophysitis)

• Other tumours near the pituitary gland

  • Rathke's cleft cysts

  • Craniopharyngiomas

  • Meningiomas

  • Chordomas

  • Gliomas

  • Epidermoid cysts

What symptoms of pituitary disorders

Pituitary disorders symptoms vary dependant on the hormone affected. Outlined below are the symptoms cause by abnormal hormone levels:

What if a pituitary disorders is not treated

• The nature of the pituitary disease determines the prognosis.  

• If a pituitary disorder is not treated it leads to ongoing or worsening symptoms, visual loss from compression of the optic chiasm, pituitary failure and low hormone levels.  

• In severe cases untreated disease could cause death

How are pituitary disorders diagnosed

Typically pituitary disorders can be diagnosed by:

• History and medical examination

• Neurological examination

• Pathology tests

  • Blood tests including hormone levels

  • Biopsy (not required commonly)

• Radiology tests

  • MRI scan

  • Computed tomography (CT Scan)

• Visual field testing

How are pituitary disorders treated

• Treatment depends on which type of pituitary disorder and which hormone is affected.

• If pituitary hormone levels are low an endocrinologist can prescribe hormone replacement  in the form of tablets, patches, injections or nasal sprays.

• If pituitary hormone levels are high the treatment options may include blocking the hormones using medications, pituitary surgery or pituitary radiotherapy.

• The table below outlines treatments related to the hormones affected: