Pituitary - Clinical Flashcards
What are causes of hyperprolactinaemia?
- Prolactinoma
- Co-secretion of prolactin in tumours causing acromegaly
- Stalk compression - pituitary adenomas
- PCOS
- Primary hypothyroidism
- Idiopathic
- Oestrogen therapy
- Renal failure
- Liver failure
- Drugs - anti-psychotics, anti-emetics
How would you distinguish whether a tumour was a macroprolactinoma or was causing stalk compression?
Macroprolactinoma would have a relatively bigger increase in prolactin levels compared to stalk compression
What is acromegaly?
Clinical syndrome caused by excess secretion of GH. GH stimulates skeletal and soft tissue growth. GH excess therefore produces gigantism in children (if acquired before epiphyseal fusion) and acromegaly in adults. Both are due to a GH secreting pituitary tumour (somatotroph adenoma) in almost all cases.
What are causes of GH excess in ACromegaly?
- Pituitary tumour - 99%
- Hyperplasia due to ectopic GH secreteing tumour - carcinoid
Which MEN syndrome is acromegaly most commonly associated with?
MEN-1
What symptoms seen in acromegaly?
- Change in appearence
- Sweaty
- Increased size of hands and feet
- Headaches
- Visual deterioration
- Tiredness
- Weght loss
- Amenorrhoea/Oligomenorrhoea
- Galactorrhoea
- Impotence/poor libido
- Deep voice
- Goitre
- Breathlessness
- Poluria/polydipsia
- Joint pain
What are signs of acromegaly?
- Prominent supraorbital ridge
- Prognathism
- Interdental separation
- Large tongue
- Hirsutism
- Thick greasy skin
- Spade like hands and feet
- Tight rings
- Carpal tunnel syndrome
- Colonic polyps
- Visual field defects
- Galactorrhoea
- HTN
- Oedema
- Arthropathy
- Proximal myopathy
- Glycosuria
What is prognathism?
Abnormal protrusion of one or both jaws, particularly the mandible, relative to the broader facial skeleton
What is proximal myopathy?
Weakness of the proximal muscles of the girdle including the quadriceps and biceps. Can be easily demonstrated by asking the patient to rise from a seated position and/or to pretend to be brushing their hair or hanging out washing.
What is macroglossia?
Enlargement of the tongue disproportionate to jaw and oral cavity size; also described as a resting tongue that protrudes beyond the teeth or alveolar ridge.
True macroglossia is defined as macroglossia with characteristic hypertrophied or hyperplastic histological findings. Pseudomacroglossia is said to be tongue enlargement seen in relation to a small mandible but also with histological abnormalities
What is hirsuitism?
Excessive hair growth on the face and body, in particular associated with a male-type pattern of hair growth in women.
What is galactorrhoea?
Lactation occurring in non-breastfeeding females. It is always pathological in males.
What is the mechanism behind galactorrhoea?
Hyperprolactinaemia and galactorrhoea may be caused by:
- Excess prolactin secretion
- Disruption of the normal inhibitory process of dopamine
- Failed excretion of prolactin.
What is the mechanism of galactorrhoea in acromegaly?
- Mass effect of the pituitary adenoma causing stalk compression
- Excess growth hormone that has a stimulatory effect on prolactin
- Very rare cases, a pituitary adenoma may produce both growth hormone and prolactin.
How does stalk compression cause hyperprolactinaemia?
Stalk compression by any cause (e.g. craniopharyngioma, trauma, pituitary adenoma) disrupts or destroys the normal tuberoinfundibular pathway that allows dopamine to travel from the arcuate nucleus, via the portal circulation, to the lactotrophs to inhibit prolactin secretion. Hyperprolactinaemia follows.
What are prolactinomas?
Prolactinomas are a type of pituitary adenoma, a neoplastic growth of pituitary lactotroph tissue. Prolactinomas secrete prolactin in large quantities and are not effectively inhibited by normal levels of dopamine.
Why does hyperprolactinaemia occur in primary hypothyroidism?
In hypothyroidism, thyrotrophin-releasing hormone (TRH) is elevated as a compensatory response to low thyroxine. TRH is a potent prolactin-releasing factor.
What visual problems might someone have if they have acromegaly?
Bitemporal haemianopia
If you suspected acromegaly, what investigations would you perform?
- Bloods - Ca2+, PO43-, GH day curve, Prolactin levels, IGF-1
- OGTT
- Formal visual field examination
- MRI scan - pituitary
- Pituitary function
If you found on investigation of someone with suspected acromegaly raised GH and IGF-1 levels, what investigation might you do?
OGTT
What result on OGTT might indicate acromegaly?
Lack of suppression of GH - diagnostic if there is no suppression of GH. Acromegalics fail to suppress GH below 0.3 µg/L and some show a paradoxical rise; about 25% of acromegalics have a positive diabetic glucose tolerance test.
What might you find on investigation of prolactin levels in someone with suspected acromegaly?
Mild to moderate hyperprolactinaemia occurs in 30% of patients. In some, the adenoma secretes both GH and prolactin.
What would indicate active disease in someone with acromegaly?
- Sweaty skin
- Boggy tissue
What is involved in trans-sphenoidal surgery?
A type of surgery in which an endoscope and/or surgical instruments are inserted into part of the brain by going through the nose and the sphenoid bone (a butterfly-shaped bone forming the anterior inferior portion of the brain case) into the sphenoidal sinus cavity. Transsphenoidal surgery is used to remove tumors of the pituitary gland. (Such tumours, although within the skull, are outside the brain itself).
What cranial nerves are most commonly affected in pituitary lesions?
Those in the cavernous sinus
- Optic nerve
- IIV, IV, VI
