Understanding Pituitary Disorders

Take-home points

• Pituitary disorders occur when the pituitary gland makes too much or too little of a pituitary hormone(s).
• Pituitary disorders can be caused by problems in the hypothalamus or the pituitary gland. The most common cause is a pituitary tumour, which can account for up to 61% of cases of hypopituitarism.
• The specific symptoms of pituitary disorders will largely depend on the type of pituitary disorder present.
• Treatment options range from hormone replacement therapy, surgery, and radiation therapy, though treatment will depend on the type of pituitary disorder.

What is the pituitary gland?

The pituitary gland, also known as the hypophysis, is located at the base of the brain, adjacent to the hypothalamus, and connected by a stalk.^1,2 Its primary function is to release several hormones that regulate various processes within the body, including growth, metabolism, reproduction, and response to stress. ² The pituitary gland is regulated by the hypothalamus, and the connection between the two allows for external stimuli (such as stress) and internal stimuli (other hormones) to trigger the release of pituitary hormones. ^1,2

What are pituitary hormones?

Pituitary hormones are hormones secreted by the pituitary gland. The pituitary gland consists of two primary organs: the anterior pituitary and the posterior pituitary. The anterior pituitary is the part of the pituitary gland that is responsible for releasing hormones, whereas the posterior pituitary stores hormones produced by the hypothalamus. The hypothalamus in the brain regulates the anterior pituitary by secreting ‘’releasing hormones’’ such as somatostatin and dopamine. These two hormones are secreted directly into the blood vessels that supply blood to the anterior pituitary. Once these hormones arrive in the pituitary, they either stimulate or inhibit the release of the following key pituitary hormones:²

• Growth hormone: Supports growth, particularly during childhood³
• Thyroid-stimulating hormone: Controls the production and release of hormones from the thyroid gland⁴
• Adrenocorticotropic hormone: Stimulates the adrenal glands to produce cortisol, a key hormone that helps regulate mood and stress⁵
• Follicle-stimulating hormone: Plays a critical role in reproductive health⁶
• Luteinizing hormone: Stimulates the Leydig cells within the testes to synthesise and release testosterone⁷

What are pituitary disorders?

Pituitary disorders occur when the pituitary gland makes too much or too little of a pituitary hormone(s). Some examples of pituitary disorders, and their hormone imbalances are listed below:⁸

• Too much cortisol in the body: Cushing’s disease
• Too much growth hormone in the body: Acromegaly
• Low cortisol and aldosterone: Adrenal insufficiency
• A deficiency of one or more pituitary hormones: Hypopituitarism  

It’s estimated there are around 70,000 patients in the United Kingdom with pituitary disorders.

What causes pituitary disorders?

Pituitary disorders can be caused by problems in the hypothalamus or the pituitary gland. The most common cause is a pituitary tumour, which can account for up to 61% of cases of hypopituitarism. Most pituitary tumours are benign and grow either on or near the pituitary gland resulting in a change in hormone production.

Symptoms of pituitary disorders

The specific symptoms of pituitary disorders will largely depend on the type of pituitary disorder present. Though common symptoms of pituitary disorders include:⁹

• Anxiety or depression  
• Diabetes  
• Hair loss  
• High blood pressure  
• Irregular menstrual periods  
• Unexpected breast milk production  
• Low energy or low sex drive  
• Stunted growth or unusual growth spurts  
• Unexplained weight gain
• Vision changes  

If you experience any of these symptoms, you must visit your doctor for further investigation.

Diagnosing pituitary disorders

Pituitary disorders are typically diagnosed using hormone tests. These tests can measure hormone levels in the blood, urine, or saliva. Some clinics may also offer dynamic tests, which involve injecting hormones into the body to observe how the body responds. ¹⁰

Treating pituitary disorders

There are a variety of treatment options for pituitary disorders, and the specific treatment will depend on the underlying cause. Some common treatments include:

Hormone replacement therapy

Hormone replacement therapy is used to restore hormonal levels within the body to their normal range. The purpose of hormone treatment is to address deficiencies in hormone production, particularly those related to the pituitary gland. The hormones that are commonly prescribed for pituitary hormone replacement therapy include:¹¹ 

• Cortisol
• Thyroid hormone
• Vasopressin
• Sex hormones
• Growth hormone.  

In the case of patients with a pituitary tumour, specific medications will be prescribed to address the tumour type.

Surgery for pituitary disorders

In some cases, pituitary surgery may be necessary. These cases include pituitary adenomas, a common benign pituitary gland tumour. Surgery may also be recommended to remove hormone-producing tissue, a common form of surgery for patients with acromegaly (overproduction of growth hormone) and Cushing's disease (overproduction of cortisol).¹²  

Radiation therapy

Radiation therapy for pituitary tumours is a treatment that uses high-energy radiation to kill cancer cells in the pituitary gland. It is often used when surgery is not possible or when tumour cells remain after surgery.¹³

The two common radiation therapies used for pituitary tumours are:¹³

1. External Beam Radiation Therapy (EBRT): Delivers radiation from outside the body using a machine called a linear accelerator. The radiation is carefully targeted at the tumour site to minimise damage to surrounding healthy tissues. EBRT is typically administered over a series of sessions, with each session lasting only a few minutes.

2. Stereotactic Radiosurgery (SRS): SRS uses highly precise radiation beams to target and treat tumours while minimising exposure to nearby healthy tissues. SRS can typically be completed in a single session and can be delivered by modern medical devices such as Gamma Knife or CyberKnife.  

If you experience any symptoms that may be indicative of a pituitary disorder, it’s recommended to visit your doctor for further investigation, to ensure you receive the correct diagnosis and if necessary, the right treatment.  

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References:

1. Wilkinson M, et al. In Intro to Neuro 2015.doi:10.1017/CBO9781139045803.004
2. Rawindraraj AD, et al. Physiology, Anterior Pituitary; StatPearls 2023.
3. Brinkman JE. et al. Physiology, Growth Hormone; StatPearls 2022.
4. Shahid MA, et al. Physiology, Thyroid Hormone. StatPearls 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500006/.
5. Allen MJ, Sharma S. Physiology, Adrenocorticotropic Hormone (ACTH). StatPearls 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500031/.
6. Dandona P, Rosenberg MT. Int J Clin Pract 2010;64(6):682015096.
7. Nedresky D, Singh G. Physiology, Luteinizing Hormone. StatPearls 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539692/.
8. The Pituitary Foundation, Pituitary Conditions. Available at: https://www.pituitary.org.uk/information-index/pituitary-conditions/conditions/.
9. Oregon Helath & Science University. Understanding Pituitary Disorders. Available at: https://www.ohsu.edu/brain-institute/understanding-pituitary-disorders.
10. Oregon Helath & Science University. Pituitary Disorders: Diagnosis and Treatment. Available at: https://www.ohsu.edu/brain-institute/pituitary-disorders-diagnosis-and-treatment.
11. Smith JC. Expert Opin Pharmacother 2004;5(5):1023–31.
12. Buchfelder M, Schlaffer S. Clin Endo & Metab 2009;23(5)525–692.
13. Sheehan JP, et al. Neurosurg Clin N Am 2012;23(4):571–86.