Pituitary tumours Flashcards
How are tumours tested for classification
MRI
How are pituitary adenomas classified?
Microadenoma <1cm. Macroadenoma >1cm. Sellar or supracellar. Invading cavernous sinus or not. compressing optic chiasm?
What is the name of a functioning somatotroph adenoma?
Increased growth hormone secretion resulting in acromegaly
What is the name of a functioning lactotroph adenoma?
Increased prolactin secretion and prolactinoma
What is the name of a functioning thyrotroph adenoma?
Increased TSH secretion resulting in TSHoma
What is the name of a functioning gonadotropin adenoma?
Increased LH and FSH resulting in gonadotrophinoma
What is the name of a functioning Corticotroph adenoma?
increased ACTH secretion resulting in Cushing’s disease, corticotroph adenoma
How does hyperprolactinaemia result in oligo-amenorrhoea, low libido, infertility and osteoporosis?
Prolactin binds to prolactin receptors on kisspeptin neurons in the hypothalamus, inhibiting kisspeptin release. This results in a decrease in downstream GnRH/LH/FSH, which in turn results in a decrease in oestrogen/ testosterone
How does a prolactinoma present and what serum prolactin levels would be found in the blood?
> 5000 mU/L , proportional to the tumour size. Presents with menstrual disturbance/erectile dysfunction, reduced libido, galactorrhoea, subfertility
When should a pituitary MRI be ordered for someone with a suspected prolactinoma?
Once confirmed a true pathological elevation of serum prolactin
Other than a prolactinoma, what are other causes of elevated prolactin?
Physiological: pregnancy, stress, exercise, seizure, primary hypothyroidism, PCOS, chronic renal failure,SSSRIs, anti-emetics, opiates, high dose oestrogen
How can a prolactinoma be treated?
Dopamine receptor agonists.
How does acromegaly present?
Often insidious presentation, mean time to diagnosis = 10 years, sweatiness, headache, coarsening of facial features, increase in hand and feet size, macroglossia, hypertension, obstructive sleep-apnoea, impaired glucose tolerance
How is acromegaly diagnosed?
Clinical symptoms and measurements, failed suppression (paradoxical rise) of GH following oral glucose load.
True or false, you can measure random serum GH to diagnose acromegaly?
GH is pulsatile therefore random measurements are unhelpful
How is acromegaly treated?
First line treatment is surgical, a trans-sphenoidal pituitary surgery, which aims to normalise serum GH and IGF-1. Can use medical treatment such as somatostatin analogues and dopamine agonists
What are the two types of causes of Cushing’s syndrome?
Can be ACTH dependent or ACTH independent
What are some ACTH dependent causes of Cushing’s disease?
Corticotroph adenoma, ectopic ACTH (lung cancer)
What are some ACTH independent causes of Cushing’s disease?
Taking steroids by mouth, adrenal adenoma or carcinoma
What are the symptoms of Cushing’s disease?
Moon face, reddened cheeks, central obesity, buffalo hump, proximal myopathy resulting in the inability to stand from a squat, easy bruising, purple striae,
What is the difference between Cushing’s syndrome and cushings disease?
Syndrome = excess cortisol, disease = corticoadenoma secreting ACTH
How do we investigate Cushing’s disease?
Elevated 24h urine free cortisol, elevated late night cortisol, failure to suppress cortisol after oral dexamethasone. Once confirmed hypercorticolism, measure ACTH, if ACTH high pituitary MRI ACTH dependent
How do non-functioning pituitary adenomas present?
Often with visual disturbance (bitemporal hemianopia), can present with hypopituitarism, serum prolactin can be raised
Why can serum prolactin be raised in non-functioning pituitary adenomas?
Dopamine cant travel down pituitary stalk from hypothalamus
