2 - Hypersecretion of Anterior Pituitary Hormones Flashcards
(32 cards)
What is hyperpiuitarism?
Excess pituitary hormone secretion
What are the main causes of hyperpiuitarism?
- Isolated pituitary tumours
- Ectopic origin (e.g. non-endocrine tissue secreting pituitary hormones)
e.g. in Cushing’s when ACTH comes from the gut
What symptoms are associated with hyperpiuitarism?
- Visual field defects due to a compressed optic chiasm as the pituitary gland tumour grows upwards into it
- Other cranial nerve defects
- Endocrine signs and symptoms
What is the pattern of sight loss typically presented as a result of hyperpiuitarism?
BITEMPORAL HEMIANOPIA
- optic chiasm compression due to suprasellar (above sella turcica) growth of pituitary tumour
- nasal retinae supplies outer visual field of eye
How is a bitemporal hemianopia assessed?
Perimetery
- screen with flashing lights
- press button every time you see a light flash
- build picture of position of lights seen
- assess visual field of person
What can excess of the APG hormones cause clinically?
ACTH - Cushing's Disease TSH - Thyrotoxicosis LH/FSH - Precocious puberty in children Prolactin - Hyperprolactinaemia GH - Gigantism, Acromegaly
What is the difference between Cushing’s Disease and Cushing’s Syndrome?
Disease = cause is specifically a pituitary adenoma Syndrome = cause is anything, just too much cortisol
What defines lactation as hyperprolactinaemia?
Physiological = pregnancy, breastfeeding Pathological = prolactinomas (most common functioning pituitary tumour)
What is special about prolactinomas?
They are often micro adenomas, which are less than 10mm in diameter.
What can high prolactin also do within the body, beside cause lactation?
Suppress GnRH pulsatility
What symptoms can hyperprolactinaemia, due to a pituitary adenoma, cause in women?
- Galactorrhea
- Secondary amenorrhea (periods stop)
- Oligomenorrhea (infrequent periods)
- Loss of libido
- Infertility
What symptoms can hyperprolactinaemia, due to a pituitary adenoma, cause in men?
- Galactorrhea (uncommon)
- Loss of libdo
- Erectile dysfunction
- Infertility
What cells in the APG secrete prolactin?
Lactotrophs
How does Dopamine work alongside Prolactin?
Dopamine is a brake on Prolactin
- comes from hypothalamic dopaminergic neurones
- binds to D2 receptors on lactotrophs
- inhibition of lactotroph
- prolactin secretion is inhibited
- therefore, high dopamine = low prolactin
What can be used to treat hyperprolactinaemia?
D2 (dopamine receptor) agonists
- normally surgery is used for endocrine tumours
- but microadenomas are difficult to remove
- drug taken for about 3 years (1-3x per week)
- oral administration
- it shrinks the tumour as well as reducing prolactin levels
What are some examples of D2 agonists?
Bromocriptine
Cabergoline (can cause psychiatric problems, so patients need to be monitored - pathological gambling)
- nausea is more common with B than with C
What are some side effects of Dopamine receptor agonists?
- nausea and vomiting
- postural hypotension
- dyskinesias
- depression
- pathological gambling
What can excess GH cause in children and adults?
Children - Gigantism
Adults - Acromegaly
What is excess growth hormone typically the result of?
Usually a benign pituitary adenoma
- benign because it’s not cancer but still causes bad side effects
What is different in the onset of Acromegaly compared to Gigantism?
Acromegaly is more insidious and subtle in its onset. Signs and symptoms gradually progress and can remain undiagnosed for years.
What is Acromegaly?
Not a growth in height, but a growth in soft tissue mainly
- periosteal bone
- cartilage
- fibrous tissue
- connective tissue
- internal organs (e.g. cardiomegaly, splenomegaly etc)
What can happen if Acromegaly is left untreated?
It’s associated with morbidity and mortality.
DEATH
- cardiovascular disease (60%)
- respiratory complications (25%)
- cancer (15%)
What are the clinical features of Acromegaly?
- excessive sweating (hyperhidrosis)
- headache
- enlargement of supraorbital ridges, nose, hands, feet, thickening of lips, coarseness of many features
- macroglossia
- prognathism (mandible grows, jaw protrusion)
- carpal tunnel syndrome
- barrel chest
- kyphosis (outward curvature of the spine)
Why is carpal tunnel syndrome a feature of acromegaly?
Due to median nerve compression in the hand.
