The pituitary gland is a small gland found at the base of the brain. The gland has two parts, the posterior (back) pituitary and the anterior (front) pituitary. This gland sits within a small bone cavity called the sella turcica that is located behind the eye sockets and the nose sinuses.
The pituitary gland sits right beneath the Optic Chiasm which is the confluence of our two optic nerves. On both sides of the sella, Internal carotid arteries pass which supply almost two-third of our brain. and nerves pass close to the pituitary gland in an area called the cavernous sinus (sinus cavity).
What are the hormones produced by the Pituitary gland?
Pituitary gland is called the Master Gland of the body as it controls most of the important hormones of the body, directly or indirectly. It is a key link between the brain and other glands in the body.
The anterior pituitary makes many hormones:
Prolactin is a hormone that is needed to make breast milk.
• ACTH controls steroids made by the adrenal gland.
• TSH controls the thyroid.
• Two other hormones (FSH and LH) control the production of sex hormones and fertility.
• Growth hormone is responsible for linear growth and height in children and maintenance of bone and muscle mass in adults.
The posterior part of the pituitary is a direct extension of the brain and stores two hormones:
• Antidiuretic hormone works on the kidneys to regulate water loss.
• Oxytocin controls contractions when a woman goes into labor.
What are Pituitary tumours?
A pituitary tumuor is an abnormal growth of cells in the pituitary gland. Almost all tumours begin in the anterior pituitary. Depending upon the size the Pituitary tumours are called ‘Microadenomas’ if they are <10mm, or ‘Macroadenomas’ if they are >10mm in size.
How are pituitary tumours classified?
Based on size they are Microadenomas or Macroadenomas.
Another way of classifying the Pituitary tumors is based on their production of hormones. Majority of tumors are non-functional tumors, that is they do not overproduce any hormone. Functional tumors produce excess of a particular hormone.
How do Non-functional Pituitary tumours present?
As these tumours do not produce any hormones, the manifestations are related to the size of tumor and pressure on the adjacent structures of the brain and nerves. A tumour may:
• Cause the pituitary gland to make too many or too few hormones.
• Cause vision loss if it causes pressure on the optic nerve or more commonly Optic chiasm
• Cause difficulty with eye movement if it pushes on nerves responsible for eye movements.
• Cause headaches
• Cause no symptoms at all, detected incidentally, called ‘Incidentalomas’
How do the functional Pituitary tumours manifest?
Functional Pituitary tumours present because of overproduction of hormones leads to different manifestations.
Acromegaly or Gigantism- Because of excess of Growth hormone.
Cushings Disease- Because of excess of ACTH production, thereby increasing Endogenous steroid production.
Prolactinomas- Cause abnormal milk production from breasts, stops menstrual cycles, and excessive facial hair growth.
TSH producing tumours- Tumours that cause excess production of thyroid hormones are very rare.
Is Pituitary tumour a cancer?
Most pituitary tumours are benign, that is they have a slow growth rate and do not spread to other areas of the body unlike cancer. Pituitary cancer is very rare.
What are the Risk Factors for Pituitary tumours?
As of now, we do not know for sure what causes pituitary tumours. Pituitary tumours can happen at any age, but they are more common in older adults. Having a family history of the disease called multiple endocrine neoplasia type 1 (MEN1) raises the risk of pituitary tumours.
What is Cushing’s disease?
Cushing’s disease is when Adrenocorticotropic hormone-producing tumors of Pituitary cause the adrenal glands to make more of a hormone called cortisol.
• Weight gain around the stomach area and upper back
• Round or swollen face, ‘Moon Like facies’
• Stretch marks that are usually wide and purple in color
• Hump on the upper back and excessive fat above the collar bones
• High blood pressure
• High blood sugar
• Muscle weakness
• Thinning of the skin
• Easy bruising
• Abnormal periods and excessive hair growth (in women)
• Osteoporosis and broken bones
When these features are present it is called Cushing’s syndrome. Cushing’s disease is the specific name given to these symptoms being specifically caused by a Pituitary tumour.
What is Acromegaly and Gigantism?
These are caused by excess of growth hormones in the body.
Growth hormone-producing tumours in adult’s cause
• Rough or coarse facial features, such as enlarged jaw and prominence of forehead
• Enlarged hands and feet
• High blood pressure
• Heart problems, increase in size of heart muscle thereby weakening heart function.
• Excessive sweating
• Respiratory disorders such as sleep apnea
• Enlargement of the tongue and widening of the spaces between the teeth
• Arthritis and joint pains
• Excessive growth (gigantism) in children
If the excessive growth hormones is present in growth phase of children, that is before fusion of bone growth plates, the it causes abnormal increase in overall length of individual and limbs, causing Gigantism.
What are Prolactinomas?
Prolactin-producing tumours make too much of the hormone called prolactin.
High amounts of prolactin in the blood affect women and men differently.
For women, it may cause:
• Irregular or no menstrual periods, called Amenorrhoea
• Milky discharge from the breasts, Galatorrhoea
In men, it may cause:
• Enlarged breasts
• Erectile dysfunction (ED) or impotence
• Less body hair
• Loss of interest in sex
In children it may cause a delay in puberty.
How are Pituitary tumours diagnosed?
Sometimes Pituitary tumours may be found incidentally on a scan done for some other reason.
Magnetic resonance imaging (MRI) is the gold standard imaging for the brain to detect these tumours. CT scan is not very helpful in delineating this tumour. MRI is done with contrast and dynamic MR is better to pick up small pituitary tumours.
What are the other tests done for Pituitary tumours?
Complete hormonal blood profile is mandatory to look for baseline of all hormones, so that any deficiency of a particular hormone can be tackled fast.
Visual field charting, or Perimetry is to look for damage to your optic nerves from the pressure of tumour.
What is the treatment of Non-functional tumours?
If the tumour is incidentally detected and is not causing any significant pressure of vision pathways, the it can be observed sequentially with interval MRI and visual field charting.
For larger tumours, surgery is mandatory. Trans-nasal endoscopic route is considered the best way of surgery in current practice. It is performed by a team of Neurosurgeons and ENT surgeons, using the nasal cavity.
However, if the tumour is very large, or going out of its normal bony walls into other areas of brain, then t may not be feasible and the surgeon may opt for a trans-cranial route.
After surgery scans are done, around 3 months after surgery to see for any residue which if present can be observed or can be treated with a single high dose of radiation using Gamma Knife.
How are functional pituitary tumours treated?
Treatment depends on the hormone which is being over-produced by the tumour.
In Prolactinomas, medical treatment is the first option. The tumour is documented to just disappear with medical treatment no matter how large it was to begin with. Cabergoline is the drug of choice for this tumour, and needs to be taken twice weekly. Dose can be adjusted as per the clinical and lab response. Surgery may be required in case tumour does not respond, medicines are not tolerated or CSF starts leaking after initiation of the drug.
For other functional tumours, like Cushing’s disease or Acromegaly, surgical removal of the tumor is must. However, it may not completely solve the problem of overproduction of hormone, and some adjuvant form of medical therapy may be required to further suppress the hormone production.