Hypersecretion of anterior pituitary hormones Flashcards
What is the most common cause of hypersecretion of anterior pituitary hormones? (1)
Pituitary adenoma
What visual defect is associated with pituitary adenoma? (1)
Bitemporal hemianopia
What is bitemporal hemianopia? (1)
Bitemporal hemianopia means the temporal field of view of both the left and right visual fields is disrupted
How can bitemporal hemianopia be tested for? (1)
Perimetry. Peripheral vision won’t see the flashes of light.
What is bitemporal hemianopia caused by and why does it affect both right and left visual fields? (2)
Pituitary adenoma compresses the optic chiasm.
Optic chiasms is where fibres from both hemi-retina decussate so compression affects both visual fields
For each of the following hormones, state the disease that hypersecretion would cause:
i) ACTH
ii) TSH
iii) LH/FSH
iv) Prolactin
v) GH (5)
i) Cushing’s disease
ii) Thyrotoxicosis
iii) Precocious puberty
iv) Hyperprolactinaemia
v) Acromegaly/gigantism
How is prolactin secretion regulated and what function does it carry? (4)
- Prolactin is under inhibitory regulation by dopamine
- Under normal circumstances prolactin is NOT secreted. Inhibition of dopamine release allows for prolactin secretion
- In pregnant women functions to prepare the breast tissue for breast feeding
- Post-natally allows women to breast feed their neonates
What is the usual cause of hyperprolactinaemia? (2)
Prolactinoma
Most commonly microadenomas (< 10 mm)
State the symptoms of hyperprolactinaemia. Distinguish between the effects caused by suppression of GnRH pulsatility and those caused by elevated prolactin. (4)
In both men and women - due to loss of GnRH pulsatility (1):
- Loss of libido/infertility (1)
- Amenorrhea (women) /erectile dysfunction (men) (1)
Excess prolactin:
Galactorrhea (rare in men)
How are prolactinomas treated? (2)
- Pharmacologically: DA agonists
- E.g. cabergoline or bromocriptine
- No need for surgery
What is the effect of cabergoline or bromocriptine on prolactinomas? (2)
Reduction in tumour size
Reduced prolactin release
What are the side-effects of DA agonists like cabergoline? (3)
- Cabergoline is better tolerated than bromocriptine
- Side effects include: nausea/vomiting (for bromocriptine)
- Postural hypotension
- Dyskinesia
- Pathological gambling
- Depression
What disease is caused by excess GH? (2)
Acromegaly in adults
Gigantism in children
State some common clinical manifestations of acromegaly. (4)
- Enlarged supraorbital ridges + thickened skin/lips/nose/hands (general coarseness of features)
- Hyperhidrosis
- Headache
- Carpal tunnel syndrome (due to excessive cartilaginous growth)
- Macroglossia
- Spade-like hands (wedding ring might not fit)
- Barrel chest/khyphosis
How can acromegaly increase risk of diabetes (3)
- Excess growth hormone leads to increased endogenous glucose production
- AND decreased muscle glucose uptake
- Increased insulin production = increased insulin resistance
- Increased insulin resistance means there is impaired glucose tolerance —> diabetes mellitus
