MEH 16 - Pituitary Disorders Flashcards
What are the 2 different ways in which pituitary tumours may present clinically?
1) Mass effect of tumour on local structures - tumour can push up on optic chiasm leading to vision loss, or sideways causing painful headaches + double vision.
2) Abnormality in pituitary function - a hypo or hyper-secretion of a hormone.
Which anterior pituitary hormone is the only one under negative/inhibitory control?
- Prolactin, under inhibitory control by dopamine
- Therefore, it is the only hormone that is INCREASED by a pituitary tumour, all others will be decreased.
What are the effects of gonadotropin deficiency (FSH + LH) in children + adults?
- Delayed puberty in children
- Loss of secondary sexual characteristics in adults
- Loss of periods early sign in women
What are the effects of TSH + ACTH deficiencies?
Which one is particularly dangerous?
- TSH = low thyroid hormones, cold, weight gain, tiredness, low T4 + non-elevated TSH.
- ACTH = low cortisol, tired, dizzy, low BP, low sodium. Particularly dangerous + can be life threatening.
What kind of tests would you do if you suspected a hormone deficiency, or a hormone excess?
Hormone deficiency = Stimulation test, e.g.: stimulate adrenals w/ACTH if you suspect cortisol deficiency.
Hormone excess = Suppression test, e.g.: suppress ACTH with steroids for cortisol excess.
NB: also can use MRI to image pituitary gland in sagittal/coronal plane.
What is a prolactinoma?
What is the name given to a large/small tumour?
How should prolactinomas be treated?
- A prolactin-secreting pituitary tumour
- Large tumour (>1cm) = macro-adenoma
- Small tumour (<1cm) = micro-adenoma
- Prolactinomas treated with dopamine agonists, as dopamine inhibits prolactin release, NOT an operation, even if tumour is large causing visual problems.
What are the symptoms of hyperprolactinaemia in women?
- Menstrual disturbance
- Fertility problems
- Galactorrhea (milky discharge)
This is due to inhibition of LH and FSH due to high PRL levels.
What are the symptoms of hyperprolactinaemia in men?
- Usually present later than women (as no periods)
- Usually larger tumours (macro-adenomas)
- Symptoms of low-testosterone are non-specific
- May present with mass symptoms such as visual loss
What are the signs + causes of acromegaly?
What are the long-term symptoms of untreated acromegaly?
- Large extremities, large hands, feet + protruding jaw, caused by GH-secreting pituitary tumour.
- Premature CV death, increased risk of colonic tumours, irreversible body changes, hypertension + diabetes.
What biochemical tests would you use to confirm acromegaly?
What are the treatment options for acromegaly?
- Oral glucose tolerance test (OGTT), glucose should suppress GH, if failure to suppress <1 ug/L then diagnosis of acromegaly.
- Surgical removal of tumour, reduce GH secretion via dopamine agonist or somatostatin analogue or gamma knife radiotherapy.
What is Cushing’s disease?
What are the symptoms?
- An ACTH-secreting pituitary tumour
- Round pink face, round abdomen, thin skin, easily bruising, red stretch marks (striae) on abdomen, high BP and diabetes.
What is diabetes insipidus?
What is the difference between cranial DI + nephrogenic DI?
- Large quantities of pale (insipid) urine, leading to extreme thirst due to fluid loss.
- Cranial DI = pituitary disease leading to ADH deficiency
- Nephrogenic DI = ADH resistance kidney disease
What are the consequences of untreated DI?
- Severe dehydration, hypernatraemia, reduce consciousness coma + death
- Cranial DI responds well to synthetic ADH (desmopressin)
What is a pituitary apoplexy?
What is the clinical presentation?
- A sudden vascular event in a pituitary tumour (stroke), which can lead to haemorrhage or infarction
- Sudden onset headache, double vision, cranial nerve palsy, hypopituitarism (cortisol deficiency most dangerous).
