Acromegaly Flashcards
Acromegaly cause
Excess GH secretion
Most common - pituitary adenoma
Initial presentation of acromegaly
Middle age - starts young
T2DM + HPTN
Large fingers and toes
Visual field defect - bitemporal hemianopia or superiorquadrantopia
Clinical features of acromegaly
Coarse facial features, spade like hands, increase in shoe size
Increase inter dental spacing, large tongue, prognathism
Excessive sweating 9sweat glan hypertrophy)
Carpal tunnel syndrome
OSA - excess tissue in nose
CVD - HF, arrhythmias
Osteoporosis
Long term cancer risk
Raised prolactin -> galacotrrhea in 1/3
6% of patients MEN-1
Why does acromegaly cause visual field defect
Pituitary adenoma - pituitary crosses optic chiasm - adenoma
GH cycle
Hypothalamus -> GHRH -> pituitary -> GH -. bone, mucels, stomach, liver
Liver -> IGF-1, glucose -> Free fatty acids -> negative feedback to hypothalamus
SST from hypothalamus inhibits GH release from pituitary
What stimulates GHRH release from hypothalamus
Physical exercise
Amino acids
Hypoglycaemia
Gonadal steroids
Where does IGF-1 negatively feedback to
Hypothalamus AND pituitary
What is most accurate screening tool for acromegaly
IGF-1 - if high positive
When do an OGTT for acromegaly
When IGF-1 is moderately high but not high enough to diagnose outright
What is a positive OGTT
Non supression of GH (should be <1g/L) in response to glucose load
Ideal test for acromegaly once biochemically diagnosed
Pituitary MRI - look for enlarged pituitary or discrete adenoma
First line for acromegaly
Trans sphenoidal Surgery on pituiatry
2nd line for acromegaly post surgery
Continues GH after surgery -> pituitary radiotherapy (external beam radiotherapy), stereotactic radiosurgery, gamma radio therapy
3rd line treatment acromegaly
Medical - somatostatin analogues eg ocreotide, lanreotide LAR
Pegvisomant - high selective H receptor antagonist
Goal of acromegaly treatment
Reduce GH levels to normal range
Reduce pituitary size in case of risk of pressing on optic nerve
Long term managment of acromegaly
Cancer screening
Monitor end organ problems - ECHO, ECG, DEXA scan
Monitor IGF-1 level for recurrence
What does ocreotide do
Supress GH - example of somatostatin
50-70% success
What are a minority of acromegaly causes caused by
Ectopic GHRH or GH production by tumours eg pancreatic
Complications acromegaly
HPTN
Diabetes >10%
Cardiomyopathy
Colorectal cancer
What is normal in OGTT
GH supressed to <2mu/L with hyperglycaemia
Acromegaly - no supression
Medical options for acromegaly
Somatostatin analogue
Pegvisomant
Doamine agonists
What is pegvisomant
GH receptor antagonist
Once daily SC
V effective - 90%
Doesnt reduce tumour vol - still need surgery if mass effect
Dopamine agonists example and how work
Bromocriptine
First med used, no largely replacced by somatostatin analogues
