Understanding the Pituitary Gland
The pituitary gland is a small, pea-sized structure sitting in a bony hollow at the base of the skull called the sella turcica (Latin for "Turkish saddle"). Despite its tiny size - roughly 1 centimeter across - it is often called the master gland of the body because it controls the hormone output of nearly every other gland.
Directly above it runs the optic chiasm - the crossing point of the nerves from both eyes on their way to the brain. This anatomical closeness is exactly why pituitary tumors, when they grow upward, can affect vision before causing any other symptom. Just behind and above sits the hypothalamus, which sends chemical signals to the pituitary telling it what hormones to release and when.
The pituitary has two distinct parts, each with different functions:
Produces growth hormone (GH), prolactin, TSH (thyroid), ACTH (adrenal), FSH and LH (reproductive). Most pituitary tumors arise here.
Stores and releases ADH (controls water balance) and oxytocin. Tumors here are rare.
Sends releasing and inhibiting hormones that tell the pituitary what to produce. Large tumors can disrupt this signalling pathway.
When a pituitary tumor grows upward, it presses on the optic chiasm, classically causing loss of peripheral vision in both eyes - called bitemporal hemianopia.
What Is a Pituitary Tumor?
A pituitary tumor - medically called a pituitary adenoma - is an abnormal growth of cells within the pituitary gland. The word "adenoma" comes from the Greek word for gland, and it simply means a benign glandular tumor. The vast majority of pituitary tumors are not cancerous. They do not spread to other parts of the body.
However, "benign" does not mean harmless. A pituitary tumor can cause significant problems in two very different ways:
- 1
By secreting excess hormones - Functioning tumors produce hormones on their own, independently of the body's normal control signals, flooding the body with a specific hormone.
- 2
By pressing on nearby structures - As the tumor grows, it can compress normal pituitary tissue, press on the optic chiasm, or invade the cavernous sinuses at the sides.
Pituitary adenomas are among the most common intracranial tumors, accounting for about 10-15% of all brain tumors diagnosed. Studies of autopsy and MRI data suggest that small asymptomatic pituitary tumors are present in up to 10% of the general population - most of whom never know about them and never need treatment.
Microadenoma vs. Macroadenoma
Size matters enormously in pituitary tumors, and the distinction shapes both symptoms and treatment:
10 mm
Less than 1 cm. Usually found incidentally or because of hormone excess. Rarely causes visual problems. Excellent cure rates with surgery or medication.
10 mm
1 cm or larger. More likely to cause visual changes, headache, and hormone deficiency from compressed normal tissue. Requires surgery in most cases.
> 4 cm
4 cm or larger. Can extend into multiple areas around the sella. Requires careful staged treatment. Still treatable with experienced surgical teams.
Types of Pituitary Tumors & Their Effects
Pituitary tumors are classified by the hormone they produce. Each type has a characteristic set of symptoms - and each responds differently to treatment.
Prolactin-secreting tumors account for nearly 40% of pituitary adenomas. In women they cause irregular periods, milk discharge, and infertility. In men they cause reduced libido, erectile dysfunction, and infertility. Medication alone is usually first-line and works extremely well.
Excess growth hormone causes enlargement of the face, hands, and feet in adults, along with diabetes, high blood pressure, sleep apnoea, and joint pain. In children, it can cause excessive height. Surgery is usually the first and most effective treatment.
Excess ACTH causes chronically elevated cortisol, leading to abdominal weight gain, a round red face, thinning skin, stretch marks, high blood pressure, diabetes, depression, and bone loss. Surgical cure rates at experienced centers exceed 80%.
Rare tumors that overproduce thyroid-stimulating hormone, causing weight loss, palpitations, tremor, and heat intolerance. Treating the thyroid alone will not resolve the problem.
These tumors do not secrete a biologically active hormone in measurable excess. They are often found incidentally or because of visual loss or headache when large enough to press on nearby structures.
Occasionally, a pituitary tumor suddenly bleeds into itself or loses its blood supply. This causes a sudden severe headache, visual loss, and sometimes collapse - a medical emergency called pituitary apoplexy. It requires urgent hospital evaluation and, in many cases, emergency surgery.
Symptoms: How a Pituitary Tumor Makes Itself Known
Pituitary tumor symptoms fall into three broad categories. Many patients have a mix of all three, while others have only one type for years before a diagnosis is made.
| Category | Common Symptoms | Caused By |
|---|---|---|
| Hormone Excess | Period irregularities, milk discharge, weight gain, facial/hand enlargement, stretch marks, diabetes, high blood pressure | Functioning tumor producing excess hormone |
| Hormone Deficiency | Fatigue, low libido, infertility, weight gain, cold intolerance, dry skin, reduced body hair | Tumor compressing normal pituitary tissue |
| Local Mass Effect | Loss of peripheral vision, double vision, headache behind the eyes, rarely facial pain | Tumor pressing on optic chiasm, cavernous sinus, or dura |
The classic vision change of a pituitary tumor is loss of the outer half of the visual field in both eyes - you may notice difficulty seeing traffic from the sides, or bumping into objects you "should" have seen. Any unexplained change in peripheral vision deserves a formal visual field test and a brain MRI.
How a Pituitary Tumor Is Diagnosed
Diagnosis involves a combination of imaging, blood tests, and a visual field assessment. All three are usually needed for a complete picture.
- 1
MRI Pituitary with Contrast (Dynamic Protocol) - The gold-standard investigation. A special thin-cut MRI protocol of the sella turcica is used and must be specifically requested.
- 2
Hormonal Blood Tests - A comprehensive pituitary hormone panel measures prolactin, IGF-1, morning cortisol, ACTH, TSH, free T4, FSH, LH, and testosterone or estradiol.
- 3
Formal Visual Field Testing (Perimetry) - A dedicated test that maps exactly which parts of your visual field are affected and establishes a baseline before treatment.
- 4
Inferior Petrosal Sinus Sampling (IPSS) - A specialised test used when the source of ACTH excess is uncertain, especially to confirm Cushing's disease.
Treatment Options
Treatment depends on the type of tumor, whether it is secreting hormones, its size, and your overall health. The three main tools are surgery, medication, and radiation - often used in combination.
Medication
For prolactinomas, dopamine agonist drugs (cabergoline or bromocriptine) are so effective that surgery is rarely needed. They normalize prolactin levels, restore fertility, and shrink the tumor - sometimes dramatically - within months.
Surgery
Surgery is the primary treatment for most non-prolactinoma pituitary adenomas. The standard and most effective approach is the transsphenoidal route - operating through the nose. There is no scalp incision, no brain retraction, and no visible scar.
Radiation Therapy
Radiation is used when tumor tissue remains after surgery or when surgery is not appropriate. Modern stereotactic radiosurgery delivers a precise high dose to the residual tumor in a single session, with minimal effect on surrounding tissue.
Observation (Active Surveillance)
Small, non-functioning microadenomas that are found incidentally and cause no symptoms can safely be watched with serial MRI scans - typically at 6 months, then annually.
The best outcomes for pituitary tumors come from a team that includes a neurosurgeon, endocrinologist, ophthalmologist, and radiation oncologist working together. At a dedicated pituitary center, all these specialists review your case collectively before a treatment plan is finalized.
Transsphenoidal Surgery: What to Expect
The phrase "brain surgery through the nose" understandably surprises many patients. But understanding how this procedure works makes it far less daunting - and it is genuinely one of the most elegant approaches in all of neurosurgery.
The Surgical Route - Nose to Pituitary
(no external incision)
(through natural passage)
(air sinus at skull base)
(bony compartment)
(removed under vision)
Endoscopic vs. Microscopic Technique
Two technical approaches exist. The endoscopic endonasal technique uses a thin telescope with a camera, giving a wide panoramic view. The microscopic technique uses a surgical microscope with a speculum. Experienced surgeons may use either or a combination.
What Happens During the Operation
Under general anaesthesia, the surgeon navigates through one nostril, enlarges the natural passage through the sphenoid sinus, opens the sellar floor, and carefully removes the tumor while preserving normal pituitary tissue as much as possible. The operation usually takes 1.5 to 3 hours.
Intraoperative Technology
Modern pituitary surgery is aided by neuronavigation, intraoperative fluoroscopy, Doppler ultrasound to locate the carotid arteries, and in some centres, intraoperative MRI.
Recovery in Hospital
Most patients spend 2-3 days in hospital. Common short-term experiences include nasal congestion, mild headache, and fatigue. Hormone levels are monitored closely, particularly cortisol, sodium balance, and thyroid function.
When vision loss is caused by compression of the optic chiasm, decompression at surgery leads to meaningful vision recovery in the majority of patients - often beginning within hours and continuing over weeks to months.
Risks of Surgery
Specific risks include CSF leak, meningitis, injury to the carotid artery, damage to normal pituitary tissue causing hormone deficiency, and diabetes insipidus. Overall serious complication rates are low at experienced centres.
When Open Craniotomy Is Needed
In a small number of cases - typically giant adenomas that have grown extensively sideways, wrapped around major blood vessels, or extended far upward - a craniotomy may be required, either as a planned second stage or as the primary route.
Pituitary surgery is about restoring normal physiology as much as removing a tumor. The best operation protects vision, preserves hormone function, and removes as much tumor as safely possible.
The route through the nose is elegant because it reaches the pituitary without moving the brain. For complex or giant tumors, a staged plan may be the safest way to achieve the same goal.
Life After Pituitary Surgery
For most patients, successful pituitary surgery is genuinely life-changing. Hormone excess resolves, vision improves, headaches lift, and energy returns. Long-term follow-up, however, is an important part of the journey.
Hormone Replacement
If surgery has affected normal pituitary function, you may need hormone replacement therapy. This can include hydrocortisone, levothyroxine, testosterone or estrogen, or growth hormone. Many patients who needed replacement before surgery improve once the tumor is removed.
Follow-up MRI
A post-operative MRI is usually done at 3 months to assess how much tumor has been removed and whether residual tissue remains. Thereafter, MRI scans are repeated at intervals determined by tumor type and completeness of resection.
Hormonal Cure - Is It Confirmed?
For hormone-secreting tumors, biochemical cure is confirmed by blood tests in the weeks and months after surgery. For Cushing's disease, a low morning cortisol immediately after surgery is a strong early sign of success.
Women with prolactinomas who underwent treatment - whether medical or surgical - very commonly have full restoration of menstrual cycles and fertility. Many go on to have successful pregnancies.
Watch: Pituitary Surgery & Difficult Brain Tumor Cases
Our YouTube channel includes a dedicated section on defeating difficult brain tumors - including pituitary cases, explained in a way patients and families can understand before making decisions.
Watch on YouTube →Questions to Ask Your Doctor
These questions will help you get the most from your consultation with a neurosurgeon or endocrinologist:
- 1
What type of pituitary tumor do I have, and is it secreting hormones? - The answer changes everything about treatment choice.
- 2
What is the tumor's relationship to my optic chiasm and cavernous sinuses on the MRI? - This determines surgical risk and completeness of possible resection.
- 3
Can this be managed with medication alone, or does it need surgery? - Particularly important for prolactinomas.
- 4
How many pituitary surgeries do you perform each year? - Volume is strongly linked to outcomes in pituitary surgery.
- 5
What is the expected chance of biochemical cure with surgery for my tumor type? - Realistic expectations help you plan.
- 6
Will I need hormone replacement after surgery, and if so, for how long? - Understanding the post-operative journey avoids surprises.
- 7
Is there a pituitary multidisciplinary team (MDT) at your institution? - The best centres review complex cases collectively before recommending treatment.
Pituitary tumors are complex, and management decisions - especially for functioning tumors or giant adenomas - benefit from review at a high-volume pituitary centre. A good surgeon will welcome this. Bring your MRI scans and hormone blood test results to any second-opinion appointment.
