Hypersecretion of Anterior Pituitary Hormones Flashcards
What is hyperpituitarism?
Symptoms associated with excess production of adenohypophysial (anterior pituitary) hormones
What is hyperpituitarism usually caused by and what is the other cause?
Usually due to isolated pituitary tumours also producing ant. pituitary hormone
- Can also be ectopic (i.e. from non-endocrine tissue) in origin, basically an odd case where tissue elsewhere in the body somehow ends up making ant. pituitary hormone
What defects, signs and symptoms is hyperpituitarism often associated with?
- Visual field, cranial nerve defects due to compression of optic chiasm and cranial nerves by the tumour
- Endocrine-related signs and symptoms
What is bitemporal hemianopia and how is it caused?
Tunnel vision, blindness in lateral half of view in both eyes.
“Bitemporal” in both temporal (lateral) views
“Hemianopia” blindness in half the field of vision
Caused by impingement of optic chiasm where optic nerve fibres cross. Fibres crossing are the fibres that supply lateral vision so no signal is received by the brain from lateral view thus the blindness.
How is bitemporal hemianopia assessed and diagnosed?
Perimetry
- Flash on screen which patient responds to
- Builds an image of their vision field
- Each eye’s field of vision will be half white (can see) and half black (can’t see)
What is the difference between Cushing’s syndrome and Cushing’s disease?
Cushing’s syndrome - too much cortisol
Cushing’s disease - an ACTH-producing adenoma causing too much ACTH to be released
What disorder is caused by excess ACTH?
Cushing’s disease
What disorder is caused by excess TSH?
Thyrotoxicosis
What disorder is caused by excess gonadotrophins (LH/FSH)?
Precocious puberty in children
What disorder is caused by excess prolactin?
Hyperprolactinaemia
What disorders are caused by excess GH?
Gigantism, Acromegaly
What are two physiological (normal) causes of hyperprolactinaemia?
Pregnancy
Breastfeeding
What are the usual pathological cause of hyperprolactinaemia and what is special about it?
Prolactinoma
- Special as prolactinomas are the most common functioning type of pituitary tumour
How does high prolactin interact with other ant. pituitary hormones?
High prolactin suppresses GnRH pulsatility (think about LH/FSH low levels and no spiking during pregnancy/conception)
What are the signs and symptoms of hyperprolactinaemia in women?
- Galactorrhoea (milk production outside of when it’s needed e.g. pregnancy/birth)
- Secondary amenorrhoea or oligomenorrhoea
- Loss of libido
- Infertility (usually this or amenorrhoea as presenting feature)
These are certainly tied in with the lack of GnRH pulsatility and low gonad hormone levels
What are the signs of symptoms of hyperprolactinaemia in men?
- Galactorrheoa although uncommon (requires estrogen)
- Loss of libido
- Erectile dysfunction
- Infertility (usual presenting complaint)
How is prolactin release regulated in the pituitary gland?
Dopamine neurones via D2 receptors
- When dopamine binds, they act as a brake on prolactin release, suppressing prolactin secretion
How can the regulation mechanism of prolactin be manipulated pharmacologically to treat hyperprolactinaemia?
Dopamine receptor (D2) agonists
- decrease prolactin secretion
- reduce tumour size
What are 2 examples of dopamine receptor (D2) agonist drugs and how are they administered?
Bromocriptine
Cabergoline
- Oral administration (tablet)
Is medical (drugs) treatment or surgical treatment first-line for prolactinomas?
Medical
- Largely because the D2 agonists are so effective and also reduce tumour size
What are the side effects of dopamine receptor agonists?
- Nausea, vomiting
- Postural hypotension
- Dyskinesias (involuntary movement)
- Depression
- Pathological gambling(!)
What is the name of GH excess during childhood/teenage years and during adulthood?
Childhood - gigantism
Adult - acromegaly
What is GH excess usually due to?
“Benign” growth hormone secreting pituitary adenoma
“Benign” by definition as there are no cancer cells present, but not in terms of absence of disease-causing properties e.g. these GH excess disorders are being caused by it
What is the nature of the onset of acromegaly, how do signs and symptoms progress and what happens if excess GH is left untreated?
- Insidious in onset, very difficult to notice over years
- Signs and symptoms progress gradually over a number of years
- Untreated, excess GH is associated with increased morbidity and mortality
