S8) Pituitary Disorders Flashcards
Disorders of the pituitary gland are relatively rare.
What is the most common disorder?
The most common cause of pituitary malfunction is a benign tumour (adenoma)
Most pituitary tumours are “non-functioning”.
What does this mean?
Non-functioning pituitary tumours contain tumour cells which themselves do not produce any hormone
What is the usual consequence of non-functioning pituitary tumours?
These tumours can result in inadequate production of 1/more pituitary hormones due to physical pressure from the growing tumour on glandular tissue
What are the clinical symptoms of non-functioning pituitary tumours?
Pressure on surrounding structures in the vicinity of the tumour result in:
- Headaches
- Visual problems (optic nerve)
- Vomiting
- Nausea
Functional pituitary tumours are quite rare.
What does this mean?
Hypersecreting (functional) pituitary tumours contain tumour cells involved in the overproduction of 1/more of the pituitary hormones
What are the clinical symptoms of functional tumours?
The clinical symptoms of hypersecreting tumours usually correspond to the systemic effects of the over secreted hormone
Outline the clinical approach in the investigation of a suspected pituitary tumour
- Delineation of the anatomy, size and topographical location of pituitary / parapituitary mass (MRI scan)
- Assessment of visual field defects
- Assessment of endocrine function to determine hormonal excess/deficiency
How might one assess the endocrine function in a patient with a suspected pituitary tumour?
- Measure hormone levels in blood
- Staining sections from a biopsy of the tumour with antibodies for the relevant hormone
What is hypopituitarism?
Hypopituitarism is a state of insufficient pituitary hormone production, commonly due to a pituitary adenoma and rarely due to radiation therapy, inflammatory disease or head injury
In light of hypopituitarism, what is the consequence of the adenoma?
Progressive loss of anterior pituitary function (GH and LH/FSH first)
What is panhypopituitarism?
Panhypopituitarism is the deficiency of all anterior pituitary hormones
Why aren’t ADH and oxytocin secretion usually impaired in hypopituitarism?
Secretion of ADH and oxytocin from the posterior pituitary is usually only significantly affected if the tumour affects hypothalamic function
What are some causes of GH deficiency?
- Mass defects from pituitary adenoma
- Specific gene mutations e.g. GH-releasing hormone receptor
- Autoimmune inflammation
What are the symptoms of GH hormone deficiency secondary to mass defects from a pituitary adenoma?
- Decreased tolerance to exercise
- Decreased muscle strength
- Increased body fat
- Reduced sense of “well-being”
Why is GH deficiency often difficult to diagnose?
GH secretion is pulsatile, deficiency is often difficult to diagnose and a combination of direct and indirect measurements are required