Endocrinology Flashcards
What are the differences between steroid and peptide hormones?
Peptide hormones are synthesised as prohormones. Steroid hormones are synthesised from cholesterol.
Peptide hormones are stored in vesicles (regulatory secretion). Steroid hormones are released immediately (constitutive secretion).
Peptide hormones bind to receptors to transduce using secondary messenger systems. Steroid hormones bind to intracellular receptors to alter gene expression.
Where is the pituitary gland located?
Superior to the sella turcica of the sphenoid bone
How is bitemporal hemianopia assessed?
Visual field perimetry
How are the glands in the anterior pituitary stimulated?
Parvocellular neurons from the hypothalamus synapse at the median eminence and release factors into the capillary plexus that pass through the portal circulation and stimulate glands
What factors affect somatotrophs and what hormone do they release?
Growth hormone releasing hormone (excitatory), somatostatin (inhibitory)
Releases growth hormone
What factors affect lactotrophs and what hormone do they release?
Dopamine (inhibitory)
Releases prolactin
What factors affect corticotrophs and what hormone do they release?
Corticotrophin releasing hormone (excitatory)
Releases adrenocorticophic hormone
What factors affect thyrotrophs and what hormone do they release?
Thyrotrophin releasing hormone (excitatory)
Releases thryoid stimulating hormone
What factors affect gonadotrophs and what hormone do they release?
Gonadotrophin releasing hormone (excitatory)
Releases FSH, LH
What are the effects of growth hormone?
Causes the production of insulin-like growth factor (IGF-1, predominantly IGF-2) in the liver which can act on body tissues to bring about growth and development.
Can act directly on body tissues as well.
What is a congenital cause of hypopituitarism?
PROP1 mutation - very rare and can be picked up early due to low GH
What are acquired causes of hypopituitarism?
Tumors, radiation, infection, trauma, surgery, apoplexy, inflammation, pre-partum infarction
How is pituitary function assessed?
Dynamic blood tests
GH and ACTH levels after insulin administration (should increase)
How is GH deficiency treated? How is treatment monitored?
GH injection
QoL questionnaires and IGF-1 levels are used as indicators
What is apoplexy and how does it present? What is the immediate management?
Intra-pitutary haemorrhage or infarction. It usually has a sudden onset and can result in bitemporal hemianopia (due to blood pooling) & diplopia/ptosis (due to cranial nerve involvement in cavernous sinus). Anti-coagulants can be used as treatment.
