Anterior pituitary pathology Flashcards
What are some causes of anterior pituitary hyper function?
Pituitary adenomas
Cushing’s syndrome
What are pituitary adenomas?
Tumours arising from the cells of the anterior pituitary gland
What are the 2 main types of pituitary adenoma?
Sporadic
MEN1 associated (Wermer syndrome)
What are the 2 classes of pituitary adenomas based on size?
Micro-adenomas <1cm
Macro-adenomas >1cm
What is meant by a functioning adenoma?
A tumour that produces hormones to produce a clinical presentation
What is meant by a non-functioning adenoma?
A tumour that does not produce hormones, or produces that at a sub-clinical level
What are the most commonly produced hormones by functioning adenomas?
- Prolactin (20-30%)
- ACTH (10-15%)
- FSH/LH (10-15%)
- GH (5%)
By what classification system are pituitary adenomas classified by?
Modified Knosp classification
What are some common types of pituitary adenoma?
Prolactinomas
Somatotroph adenoma (GH secreting)
Corticotroph adenoma
What is the most common form of functional pituitary adenoma?
Prolactinoma
How will prolactinomas present in both males and females?
- Weight gain
- Delayed pubertal development
- Hypogonadism
- Infertility
- Galactorrhea
- Osteopenia or osteoporosis
How will prolactinomas present in males?
- Loss of libido
- Erectile dysfunction
- Gynaecomastia
How will prolactinoma present in females?
- Oligo-amenorrhoea
- Vaginal dryness
- Irritability
- Depression
What are some symptom of macroprolactinoma?
Headache
Visual field defects
Hypopituitarism
All caused by mass effects
What investigations are required in prolactinomas?
- Serum prolactin concentration
- Baseline pituitary function
- MRI of pituitary
- Visual field testing
What is the first line management option in prolactinoma?
Dopamine agonist (E.g. Cabergoline)
What is the use of dopamine agonists in prolactinomas?
Effective in normalising prolactin and shrinking the tumour
What are some side effects of cabergoline?
- Fibrosis (e.g. heart valves)
- Decreased impulse control (e.g. gambling, shopping)
- Psychiatric disturbance
What are some examples of dopamine agonists used in prolactinoma?
Cabergoline
Bromocriptine
Quinagolide
When is surgery indicated in prolactinoma?
Surgery is usually reserved for dopamine agonist resistant tumours, intolerance to dopamine agonists or patient preference of long term medical therapy
What hormone is secreted by somatotroph adenoma?
Growth hormone
How do somatotroph adenomas affect the body?
Growth hormone secretion causes an increase in insulin like growth factor (IGF), which stimulates growth of bone, cartilage and connective tissue
What with somatotroph adenoma cause in children (Pre-ossification)?
Gigantism
What will somatotroph adenoma cause in adults (Post-ossification)?
Acromegaly
What is acromegaly?
A condition resulting from excess growth hormone production, leading to excessive tissue growth
What are some symptoms of acromegaly?
- Thickened soft tissue (Large jaw, hands, feet, facial features)
- Obstructive sleep apnoea (Thickened nasopharynx)
- Arthropathy (Vertebral fracture, osteoporosis, carpal tunnel syndrome)
- Hypertension, LVH, cardiomyopathy
- Headaches
- Diabetes mellitus
- Dyslipidaemia
- Local pituitary effects (Visual effects, hypopituitarism)
What cancers does acromegaly increase the risk of?
Colonic polyps
Colon cancer
Thyroid cancer
How is acromegaly diagnosed?
IGF-1 levels
Oral glucose tolerance testing (Suppression test)
How is oral glucose tolerance testing performed?
Oral glucose tolerance testing is performed by giving 75g of oral glucose
GH levels are then checked at 0, 30, 60, 90 and 120 minutes
Normal response would be for growth hormone to be suppressed to <0.4ug/l after the glucose is given
In acromegaly, GH would not be suppressed and there may even be a paradoxical rise
What would a normal IGF-1 level show?
This would usually exclude acromegaly, unless there was significant liver disease
What is the first line management of acromegaly?
Pituitary surgery
What are some forms of 2nd line therapy in acromegaly?
Radiotherapy
Somatostatin analogues
Dopamine agonists
GH receptor antagonists (Last line)
What is the effects of somatostatin analogues in acromegaly?
Reduce GH levels
Cause tumour shrinkage
What are some examples of somatostatin analogues
- Ocreotide
- Lanreotide
- Pasireotide
What is an example of a GH receptor antagonist?
Pegvisomant
What screening tests are required in acromegaly?
Colon cancer screening
Blood pressure monitoring
Echocardiogram
What hormone is secreted by corticotroph adenoma?
ACTH
What condition will usually occur as a result of corticotroph adenoma?
Cushing’s disease
What is Cushing’s syndrome?
This is a pathological increase in steroid and androgen levels
What are some causes of pseudo-Cushings (Hypercortisolaemia)?
- Depression
- Alcohol dependance
- Diabetes
- Obesity
- Malnutrition
- Pregnancy
- Glucocorticoid resistance