Pituitary: prolactin, GH & hypopituitarism flashcards
21 high-yield MRCP Part 1 cards from the Intellect Medicos Endocrinology & Diabetes course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
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Name three drugs that cause hyperprolactinaemia.
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Any three of: antipsychotics (especially risperidone), metoclopramide, SSRIs/TCAs, verapamil, methyldopa, opiates.
Why? Most act by blocking dopamine, the main inhibitor of prolactin release.
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Why can primary hypothyroidism cause hyperprolactinaemia?
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Raised TRH stimulates prolactin release.
Why? Treating with levothyroxine normalises the prolactin.
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Before arranging a pituitary MRI for a raised prolactin, which three tests should be checked (besides repeating prolactin and reviewing drugs)?
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Pregnancy test, TSH and renal function.
Why? Pregnancy, hypothyroidism and CKD are common reversible causes; MRI is for persistent unexplained elevation.
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A large pituitary mass with a prolactin of 1800 mU/L is more likely to be what than a macroprolactinoma?
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A non-functioning adenoma causing stalk compression ("stalk effect").
Why? Stalk compression usually gives prolactin <3000 mU/L; a macroprolactinoma typically gives >5000 mU/L (>10,000 almost always).
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A microprolactinoma is defined as smaller than ______.
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10 mm
Why? Macroprolactinomas (≥10 mm) more often cause headache and visual field loss.
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What is the first-line treatment for a prolactinoma, even with visual field loss?
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A dopamine agonist — cabergoline is preferred.
Why? It normalises prolactin and shrinks the tumour. Surgery or radiotherapy is reserved for drug resistance, intolerance or persisting visual compromise.
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Which dopamine agonist is preferred for a prolactinoma when pregnancy is planned?
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Bromocriptine.
Why? It has the longest safety record in pregnancy.
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Which serious adverse effect is linked to high-dose cabergoline?
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Cardiac valve fibrosis (valvulopathy) — monitor with echocardiography.
Why? Common side effects are nausea, postural hypotension and vasospasm.
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What is the first-line treatment of a symptomatic non-functioning pituitary adenoma?
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Trans-sphenoidal surgery.
Why? These tumours present with mass effect and hypopituitarism, and drugs do not shrink them.
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In progressive hypopituitarism, which hormones are usually lost first and which last?
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GH and gonadotrophins (LH/FSH) first; TSH and ACTH last.
Why? Prolactin often rises early because the tumour cuts off inhibitory dopamine from the hypothalamus.
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What is the most appropriate initial (screening) test for acromegaly?
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Serum IGF-1.
Why? GH is pulsatile so a random GH is unhelpful; IGF-1 has a long half-life and reflects average GH secretion.
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What is the definitive diagnostic test for acromegaly?
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Oral glucose tolerance test with serial GH — GH fails to suppress (or rises paradoxically).
Why? In health, hyperglycaemia suppresses GH; autonomous GH secretion is not suppressed.
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What is the treatment of choice for acromegaly?
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Trans-sphenoidal surgery.
Why? IGF-1 or GH is used afterwards to monitor for recurrence.
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What is the first-choice medical therapy for acromegaly?
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A somatostatin analogue (octreotide or lanreotide).
Why? They inhibit GH release and can shrink the tumour. Dopamine agonists are less effective.
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What is the mechanism of action of pegvisomant?
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A GH receptor antagonist.
Why? It normalises IGF-1 very effectively but does not shrink the tumour, so surgery is still needed for mass effect.
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Which cancer is acromegaly associated with, warranting screening?
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Colorectal cancer.
Why? Cardiovascular disease (cardiomyopathy leading to heart failure) is the commonest cause of death.
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What is the gold-standard test for growth hormone deficiency?
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Insulin tolerance test (insulin-induced hypoglycaemia; course notes give an inadequate GH peak as <9 mU/L).
Why? Hypoglycaemia is a powerful stimulus to GH and cortisol release. Treat deficiency with somatropin.
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Name two contraindications to the insulin tolerance test.
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Any two of: epilepsy, ischaemic heart disease, untreated adrenal insufficiency.
Why? Severe hypoglycaemia can trigger seizures, ischaemia or adrenal crisis. Glucagon, arginine or GHRH stimulation are alternatives.
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A woman cannot breastfeed after a large postpartum haemorrhage and later develops fatigue and amenorrhoea. What is the diagnosis?
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Sheehan's syndrome (postpartum pituitary infarction).
Why? The pituitary enlarges in pregnancy and is vulnerable to hypotension; GH and prolactin deficiency are typical early.
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What is the most urgent drug treatment in pituitary apoplexy?
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IV hydrocortisone.
Why? Sudden haemorrhage/infarction of an adenoma causes severe headache, visual loss and acute ACTH deficiency, which can be fatal.
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What does MRI show in empty sella syndrome?
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A sella turcica filled with CSF and a flattened pituitary.
Why? It is often an incidental finding with normal or mildly reduced pituitary function.
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