Pituitary Tumours

What are pituitary tumours? 

Pituitary tumours are abnormal growths that develop in the pituitary gland, a small pea-sized structure located at the base of the brain. The pituitary gland plays a central role in regulating the body’s hormones, influencing growth, metabolism, reproduction and stress response. Although often referred to as the “master gland,” it is itself controlled by the hypothalamus.

Most pituitary tumours are benign (non-cancerous) adenomas, meaning they do not spread to other parts of the body. However, even benign tumours can cause significant health problems by producing excess hormones or by pressing on nearby structures such as the optic nerves. Rarely, pituitary tumours may be malignant, though pituitary cancer is extremely uncommon.

Depending on their behaviour, pituitary tumours are classified as functional (hormone-secreting) or non-functional (not producing hormones). Functional tumours may lead to specific clinical syndromes such as Cushing’s disease, acromegaly or prolactinoma, while non-functional tumours are often detected when they grow large enough to cause symptoms from hormone deficiencies, headaches or vision changes.

Types of pituitary tumours 

Pituitary tumours are classified based on whether or not they produce hormones and, if so, which hormones they release in excess. This distinction is important because it determines the symptoms a patient develops and guides treatment decisions. They are also characterised by size, with tumours larger than 1cm characterised as macroadenomas. Even non-functional (discussed below) can cause symptoms if larger than 1cm.

• Functional pituitary tumours — these actively secrete hormones and cause specific clinical syndromes:

• Prolactin-secreting tumours (prolactinomas) — the most common type, leading to symptoms such as irregular or absent menstrual periods, infertility and milk production (galactorrhoea) in women, and reduced testosterone, erectile dysfunction and infertility in men. Dr  Dinesh comments that these tumors are often found after screening for infertility. 

• Growth hormone-secreting tumours — excess growth hormone causes acromegaly in adults (enlarged hands, feet and facial features) and gigantism in children (Increased height in addition to acromegaly symptoms).

• ACTH-secreting tumours — these stimulate the adrenal glands to produce excess cortisol, resulting in Cushing’s disease (the most common cause of cushing’s syndrome).

• TSH-secreting tumours — rare, but can cause symptoms of hyperthyroidism such as weight loss, palpitations and heat intolerance.

• Other rare types — Some tumours may secrete multiple hormones or produce less common hormonal patterns.

• Non-functional pituitary tumours — these do not produce active hormones but may cause problems by pressing on surrounding structures. Symptoms may include headaches, vision disturbances due to compression of the optic nerves or low hormone levels if the normal pituitary gland is suppressed. Dr. Dinesh comments that these are actually more common than secretory tumours. 

• Malignant tumours — pituitary cancer is extremely rare. Most pituitary tumours are benign adenomas, and even when large, they are not cancerous.

Recognising the type of pituitary tumour is essential for accurate diagnosis and tailoring treatment to each patient’s needs.

What causes pituitary tumours? 

In most cases, the exact cause of pituitary tumours remains unclear. They often occur sporadically, without any obvious environmental trigger or family history. However, research has identified several possible contributing factors:

• Genetic mutations — changes within pituitary cells can disrupt normal growth control, leading to uncontrolled cell division and tumour formation.

• Inherited syndromes — rarely, pituitary tumours are linked to conditions such as multiple endocrine neoplasia type 1 (MEN1), Carney complex or familial isolated pituitary adenoma (FIPA), which increase the risk of developing pituitary and other endocrine tumours.

• Hormonal regulation abnormalities — disruptions in the complex feedback system between the hypothalamus, pituitary gland and target organs may contribute to abnormal cell growth in the pituitary.

• Unknown or sporadic factors — the majority of pituitary tumours develop without a clear cause, highlighting the role of unpredictable or still unidentified mechanisms.

What are the symptoms of pituitary tumours? 

The symptoms of pituitary tumours vary depending on whether the tumour produces hormones (functional) or simply causes pressure on nearby structures (non-functional). Many symptoms develop gradually, which can make early recognition difficult.

• Hormone-related symptoms — functional tumours may cause specific conditions linked to the hormone they overproduce:

• Prolactinomas — irregular or absent periods, infertility, milk production (galactorrhoea) in women; reduced testosterone, erectile dysfunction and infertility in men.

• Growth hormone-secreting tumours — acromegaly in adults (enlarged hands, feet and facial features) or gigantism in children.

• ACTH-secreting tumours — features of Cushing’s disease, including weight gain, thinning skin, muscle weakness and high blood pressure.

• TSH-secreting tumours — symptoms of hyperthyroidism such as weight loss, palpitations, sweating and heat intolerance.

• Pressure-related symptoms — non-functional tumours or large adenomas can press on nearby structures, leading to:

• Vision changes — blurred vision, double vision or loss of peripheral vision due to pressure on the optic nerves.

• Headaches — persistent or worsening headaches caused by tumour growth.

• Pituitary insufficiency — reduced production of normal pituitary hormones, leading to fatigue, low libido, menstrual disturbances or thyroid and adrenal hormone deficiencies.

Recognising these patterns is crucial, as timely diagnosis and treatment can prevent long-term complications.

What are the complications of pituitary tumours? 

If left untreated, pituitary tumours can lead to serious and lasting health problems. Complications may arise from both hormone imbalances and the tumour’s physical pressure on nearby structures.

Hormonal complications 

• Excess hormone production — can result in conditions such as Cushing’s disease, acromegaly or hyperthyroidism, each with significant long-term risks.

• Hormone deficiency (hypopituitarism) — large tumours or surgery may damage normal pituitary tissue, reducing hormone output and causing fatigue, infertility, low thyroid function or adrenal insufficiency.

Vision and neurological problems 

• Visual field loss — compression of the optic nerves can cause partial or permanent vision loss, particularly affecting side (peripheral) vision.

• Headaches — persistent headaches are common due to pressure effects.

• Rare complications — very large tumours may press on surrounding brain tissue, causing increased pressure in the brain and further neurological issues.

Surgical and treatment-related risks — surgery and radiotherapy are effective treatments but can lead to complications such as infection, bleeding or long-term hormone deficiencies requiring lifelong replacement therapy.

Without timely diagnosis and management, these complications can severely affect quality of life. Early treatment helps reduce risks and improve long-term outcomes.

Who is at risk of pituitary tumours in Singapore? 

Pituitary tumours can affect people of any age, but certain groups have a higher likelihood of developing them.

• Age and sex — most pituitary tumours are diagnosed in adults between the ages of 30 and 60. Some types, such as prolactinomas, are more commonly seen in women of reproductive age, while others affect men and women equally.

• Genetic factors — a small proportion of cases are linked to inherited syndromes such as multiple endocrine neoplasia type 1 (MEN1), Carney complex, or familial isolated pituitary adenoma (FIPA). People with a family history of these conditions are at increased risk.

• Other medical conditions — rarely, individuals with a history of endocrine disorders or other tumours may be more likely to develop pituitary tumours, although in most cases no clear trigger is identified.

• General population — for the majority of patients, pituitary tumours develop sporadically without any family history or identifiable risk factor, making early recognition of symptoms especially important.

How are pituitary tumours diagnosed?

Diagnosing a pituitary tumour involves a combination of clinical assessment, laboratory tests and imaging studies. Because many symptoms overlap with other conditions, a thorough evaluation is essential.

• Medical history and examination — doctors begin by reviewing symptoms such as vision changes, menstrual irregularities or unexplained weight or growth changes, alongside a physical examination to look for hormone-related signs.

• Hormone testing — blood and urine tests are carried out to check for abnormal levels of pituitary or target gland hormones, such as prolactin, cortisol, growth hormone, thyroid hormones or sex hormones. Special stimulation or suppression tests may be used for confirmation.

• Imaging studies — MRI scans of the pituitary are the preferred method to visualise the pituitary gland and identify the size, location and characteristics of any tumour. They require contrast to be injected. 

• Visual field testing — since large tumours can press on the optic nerves, eye examinations are often performed to detect early changes in peripheral vision.

Accurate diagnosis helps determine the type of tumour, whether it is functional or non-functional and the most appropriate treatment plan.

What are the treatment options for pituitary tumours?  

Treatment depends on the type of tumour, whether it is producing hormones, its size and the symptoms it causes. The main goals are to normalise hormone levels, relieve pressure on surrounding structures and prevent long-term complications.

• Medication — certain functional tumours, especially prolactinomas, often respond well to medicines such as dopamine agonists, which can shrink the tumour and lower prolactin levels. Other drugs may be used to block excess hormone production in growth hormone- or ACTH-secreting tumours.

• Surgery — surgical removal of the tumour is often the preferred option when it is large/ causes pressure effects or excess hormone secretion that cannot be controlled with medication. Most procedures are performed through the nose using a minimally invasive technique called transsphenoidal surgery.

• Radiotherapy — if surgery is not possible, or if a tumour is not fully removed, targeted radiotherapy may be used to control growth and reduce hormone secretion. Advances in focused radiation techniques help minimise damage to surrounding tissue.This modality takes a year or more to work and is often used second line. 

• Hormone replacement therapy — when tumours or their treatment affect normal pituitary function, patients may require lifelong replacement of hormones such as cortisol, thyroid hormone or sex hormones.

Treatment is usually tailored to the individual, often involving a multidisciplinary team of endocrinologists, neurosurgeons and radiologists to achieve optimal outcomes.

Prognosis and recovery after pituitary tumours 

The outlook for patients with pituitary tumours depends on the type of tumour, its size and how well treatment controls hormone levels or relieves pressure on nearby structures. With timely diagnosis and appropriate care, most people achieve good outcomes.

• After surgery — many patients experience significant improvement after surgical removal of the tumour, especially when detected early. Minimally invasive approaches like transsphenoidal surgery generally allow quicker recovery and fewer complications. However, some patients may need additional treatment if the tumour cannot be completely removed (which is less likely if detected earlier, when the tumour is smaller).

• Long-term hormone balance — in cases where the tumour or its treatment affects normal pituitary tissue, hormone replacement therapy may be required. Regular monitoring ensures that replacement doses remain safe and effective.

• Quality of life — symptoms such as headaches, vision problems or hormonal imbalances often improve after treatment, but recovery may take time and recovery may be incomplete. Supportive care, including physiotherapy, dietary adjustments and mental health support, can help restore well-being.

• Recurrence risk — some tumours may recur months or years after treatment, which is why long-term follow-up with imaging and hormone testing is essential.

Overall, most pituitary tumours are benign and manageable. With expert treatment and regular monitoring, patients can expect a good quality of life and long-term control of the condition.

Summary 

Pituitary tumours are usually benign but can cause significant health problems through excess hormone production or by pressing on nearby structures such as the optic nerves. They may lead to symptoms including vision changes, headaches, fatigue or hormone-related disorders like Cushing’s disease, acromegaly or infertility. 

If you are experiencing symptoms that may suggest a pituitary tumour, schedule a consultation with The Metabolic Clinic for detailed evaluation, personalised treatment and long-term care.

Frequently Asked Questions (FAQs)