Acromegaly Flashcards
What controls the secretion of GH from the anterior pituitary
GHRH is stimulatory
somatostatin is inhibitory
how does GH indirectly exert its activity?
through insulin-like growth factor: IGF-1
synthesised in liver + other tissues
how does GH directly exert its activity?
directly on tissues to induce metabolic changes
what causes acromegaly?
excessive GH secretion due to benign pituitary adenoma
epidemiology
mean age at Dx: 44yrs
mean duration of symptoms: 8yrs
Clinical features from expansion and compression
headaches, visual field loss + hypopituitarism
Why might a pt get tunnel vision
(bitemporal hemianopia) from compression of the optic chiasm
Clinical features of the metabolic effects of excess GH secretion
large tongue spade-like hands and feet tight rings interdental separation protruding jaw
Comorbidities
HTN + diabetes
Investigations
plasma GH levels glucose tolerance test 1st L: Serum IGF-1 MRI Visual field defects
What would GTT show?
failure of normal suppression of serum GH 2hrs post oral glucose load
How to diagnose
do random GH and IGF-1 test
if abnormal, do GGT
aim of Mx
reduce serum IGF-1 conc to age-adjusted range
lower mean GH level to less than 5
correct hypopituitarism
manage diabetes + HTN
First line treatment? + SEs
Transsphenoidal surgical resection
SEs: hypopituitarism, diabetes insipidus, CSF infection
Radiotherapy
after surgical excision is incomplete + in combo with medical Tx
conventional: multi-fractional
stereotactic: single fraction, more accurate, less radiation to surrounding tissues
