Acromegaly Flashcards
Define
DEFINITION: constellation of signs and symptoms caused by hypersecretion of GH in adults
*Excess GH before puberty results in gigantism (before bony epiphyses fuse)
Causes
- 99% are due to a GH-secreting pituitary adenoma
- Rarely: Excess GHRH causing somatotroph hyperplasia from hypothalamic ganglio-neuroma, bronchial carcinoid or pancreatic tumours
GH stimulates bone and soft tissue growth through ↑secretion of insulin-like growth factor-1 (IGF-1)
Epidemiology
RARE, 5/1 000 000
Age at diagnosis: 40-50 years
Symptoms
Very gradual progression of symptoms over many years
↘ Headache ,↑sweating, carpal tunnel syndrome
↘ May complain of rings or shoes becoming tight
↘ Visual disturbances (optic chasms compression)
↘ Acroparestesia (akron = extremities)
↘ Hyperprolactinaemia (irregular periods, ↓libido, impotence)
↘ Symptom of hypopituitarism
Signs
Often predate diagnosis by >4 years
↘ HANDS - enlarged spade-like hands, thick greasy skin, signs of carpal tunnel syndrome, premature osteoarthritis
↘ FACE - prominent eyebrow ridge (frontal bossing), broad nose bridge, prominent nasolabial folds, thick lips, ↑gap between teeth, large tongue, Prognathism, husky resonant voice (thickened vocal cords)
↘ EYES - visual field loss, bitemporal superior quadrantanopia progressing to bitemporal hemianopia (due to pituitary tumour, compressing optic chiasm
↘ NECK - multinodular goitre
↘ FEET - enlarged
Investigation
Serum IGF-1 - useful screening test
- GH stimulates IGF-1 secretion
Oral Glucose Tolerance Test (OGTT)
- Positive result: failure of suppression of GH after 75 g oral glucose load
Pituitary Function Tests
- 9am cortisol
- Free T4 and TSH
- LH and FSH
- Testosterone
- Prolactin
MRI of Brain - visualise the pituitary adenoma
Management
Surgical - trans-sphenoidal hypophysectomy
Radiotherapy - adjunctive to surgery
Medical - if surgery is contraindicated or refused
- Subcutaneous Somatostatin Analogues
- Examples: octreotide, lanreotide
- Side-effects: abdominal pain, steatorrhoea, glucose intolerance, gallstones
- Oral Dopamine Agonists
- Examples: bromocriptine, cabergoline
- Side-effects: nausea, vomiting, constipation, postural hypotension, psychosis (RARE)
GH Antagonist (pegvisomant)
Monitor
GH and IGF1 levels can be used to monitor disease control
Complications
CVS
- Cardiomegaly
- Hypertension
Respiratory
- Obstructive sleep apnoea
GI
- Colonic polyps
Reproductive
- Hyperprolactinaemia (in 30% of cases)
Metabolic
- Hypercalcaemia
- Hyperphosphataemia
- Renal stones
- Diabetes mellitus
- Hypertriglyceridaemia
Psychological
- Depression
- Psychosis (from dopamine agonists)
Complications of Surgery
- Nasoseptal perforation
- Hypopituitarism
- Adenoma recurrence
- CSF leak
- Infection
Prognosis
GOOD with early diagnosis and treatment
Physical changes are irreversible
