Pituitary Disorders Flashcards
Describe the clinical presentation of pituitary tumours
Mass effect of tumour on local structures
Abnormality in pituitary function - visual loss, headache
hypo- or hyper-secretion
What is the mass effect of pituitary tumour on local structures?
Optic chiasm - Visual field loss due to pressure on optic chiasm
III, IV (eye movement)
Upward growth - grows superiorily - visual loss
Pituitary tumour can lead to loss of vision at the sides
Va, b nerve (pain) pain and double vision - lateral growth of pituitary tumour
internal carotid artery (blood supply) VI nerve (lateral eye movement)
Describe the hypothalamic control of the posterior pituitary
positive control- measure in the blood GH + LH / FSH + = gonadotrophins TSH + ACTH +
negative control
Prolactin - -> hypothalamus inhibits this
If you have disinhibtory smth, prolactin goes up the rest go women
What results from gonadotropin deficiency
Loss of secondary sexual characteristics in adults
Loss of periods an early sign in women
What resulte from TSH and ACTH deficiency?
Late feature of pituitary tumours
TSH deficiency – low thyroid hormones cold, weight gain, tiredness, slow pulse low T4 and non-elevated TSH
ACTH deficiency – low cortisol tired, dizzy, low BP, low sodium HPA axis most important Can be life threatening
Can have large or small tumours - large can cause pressure - compress talk etc
Which pituitary hormones are common/rare to be in excess?
Common
Prolactin
GH
ACTH - adrenal hypertrophy
Rare
TSH LH/FSH
Describe he biochemical assessment o pituitary disease
Basal blood test sufficient: Thyroid axis: fT4, TSH
Gonadal axis: LH, FSH - fsh high early in period
testosterone - men
oestradiol - women
Prolactin axis: serum prolactin
Dynamic blood test may be needed
HPA axis: 0900 cortisol
GH axis: GH / IGF-1 - growth in pulsing manner,
What are teh stimulation test and the suppression test
Stimulation test - suspected hormone deficiency
Suppression test - suspected hormone excess
Describe the dynamic assessment of the HPA axis
Adrenal axis
Deficiency
• Direct stimulation of adrenals by ACTH (synACTHen)
• Response to hypoglycaemic stress - mobilise glycogen stores (insulin stress test)
Excess
• Suppress ACTH axis with steroids (dexamethasone) - eg for Cushing’s
Glucose switches of growth hormone - eg if you eat sugar but GH high - prolonged GH
Describe the dynamic assessment of the GH axis
GH axis
Deficiency
• Response to hypoglycamic stress (insulin stress test)
Excess
• Suppress GH axis with glucose load (glucose tolerance test)
How is pituitary disease assessed radiological?
MRI
How are visual fields assessed?
If you have a lesion by right eye - light cannot get to left side of brain - blind right eye
If you get a tumour on right side near Brian - lose left side o both eyes
If you get a chiasmal lesion - by temporal hemianopsia - lease outer halves of vision in each eye
What is bi-temporal hemi-anopia?
Loss of vision of left side of left eye and right side of right eye (peripheral vision)
Highly suggestive if pituitary tumour
What is prolactinoma?
Prolactin-secreting pituitary tumour
Prolactin normally <400
Large tumour = macro-adenoma (> 1cm)
Small tumour = micro-adenoma (< 1cm)
The larger the tumour, the higher the prolactin
Prolactinomas are treated with tablets not an operation - 2 tablets of dopamine - dopamine shrinks it
Even if the tumour is very large causing visual problems
Never send a patient for surgery until prolactin levels known
What is macro-prolatinoma?
Prolactin >4000?
Tumour will shrink with dopamine agonist Remember dopamine inhibits prolactin
What is hyperprolactinaemia?
Prolactin directly inhibits LH secretion
What are the symptoms of hyperprolatinaemia in women?
Menstrual disturbance Fertility problems Galactorrhoea - milky discharge
In micro-prolactinomas serum prolactin is not that high
What are symptoms of hyperprolactinaemia in men/
Men present later than women (no periods)
Usually larger tumours (macro-adenomas)
Symptoms of low testosterone are non-specific
May present with mass symptoms such as visual loss
What will lead to prolactin disinhibition
Prolactin is under tonic inhibitory control by dopamine
Anything blocking stalk will lead to prolactin disinhibition
What are different causes of high prolactin?
If prolactin < 5,000 the high prolactin might be due to disinhibition (‘stalk effect’) rather than active prolactin secretion
If prolactin > 5,000 the high prolactin is likely to be due to active prolactin secretion (prolactinoma)
This is important as prolactinomas are treated medically but non functioning pituitary tumours are treated surgically
What is non-functioning pituitary adenoma?
No secretion of biologically active hormones
Mass effect - visual problems or headache
May secrete inactive hormones (e.g ACTH or LH / FSH)
Clinical features from are due to mass effect or symptoms of low pituitary hormones
‘hypopituitary’ bloods with disinhibition hyperprolactinaemia
Describe the treatment of prolactinoma
Dopamine agonists stimulate D2 receptor
Bromocriptine and cabergoline very effective at reducing prolactin
Remember dopamine antagonists can cause high prolactin
Anti-sickness, anti-psychotic drugs
Always check medication in a patient with high prolactin level
And make sure patient is not pregnant!
What is acromegaly?
‘Large extremities’
Te l l -tale sign is large hands and feet
GH-secreting pituitary tumour
Leading to gradual changes in features over years
Important for medical students to learn about this
The diagnosis is made by any doctor in any clinical setting
What are long term complications of untreated acromegaly?
Premature cardiovascular death
Increased risk of colonic tumours
Probably increased risk of thyroid cancer
Disfiguring body changes that may be irreversible
Hypertension and diabetes
Unpleasant symptoms
What are biochemical tests to confirm acromegaly
Oral Glucose Tolerance Test (OGTT) with GH response
Failure to suppress GH < 1 ug/L
Elevated IGF-1 level (age related reference range)
Growth Hormone Day Curve (GHDC) – elevated mean GH
Better to think of acromegaly and be wrong than not to consider it
What are treatments of acromegaly?
Surgical removal of tumour through the nose
Very specialist surgery Safe in the right hands
Tumours in cavernous sinus need additional treatment
What are additional treatments for acromegaly?
Medical treatment
1. Reduce GH secretion Dopamine agonist • Cabergoline • Bromocriptine Somatostatin analogues (SSA) • Octreotide • Lanreotide • Pasireotide
- Block GH receptor
• Pegvisomant
How can radiotherapy be used to treat (acromegaly??)
External beam - Multiple short bursts over several weeks
Gamma knife - High concentration over single time
What is a pet scan?
-a new imaging techniques
What is cushings disease?
ACTH-secreting pituitary tumour A very interesting condition Classical change in appearance • Round pink face with round abdomen • Skinny and weak arms and legs • Thin skin and easy bruising • Red stretch marks (‘striae’) on abdomen • High blood pressure and diabetes • Osteoporosis (thin bones)
What is the difference between cushings disease and Cushing’s syndrome?
Cushing’s disease is due to a pituitary tumour Cushing’s syndrome may be caused by other pathologies Adrenal tumour, ectopic ACTH, steroid medication
Harvey Cushing was a famous neurosurgeon
He described the condition and made up the treatment
So it’s allowed to be his disease when pituitary!
What is diabetes insipidus
Not to be confused with diabetes mellitus sugar diabetes (‘sweet’) ‘Diabetes’ is the Greek word for ‘Siphon’
Diabetes insipidus
Large quantities of pale (insipid) urine Extreme thirst due to fluid loss
The posterior pituitary gland secretes vasopressin (ADH) Anti-Diuretic Hormone
Lack of ADH - lose water
‘Diuresis’ means increased urine
‘Anti-diuresis’ means the opposite
What is the action of vasopressin?
It’s ADH
Aquaporins and all that
Look uo
What is the difference between cardinal DI and neprogenic DI?
Cranial DI is vasopressin deficiency pituitary disease
Nephrogenic DI is vasopressin resistance kidney disease
Diabetes insipidus is unusual in standard pituitary tumours
Standard pituitary tumours just affect anterior pitutiary
Types of pathology that cause cranial DI • Inflammation • Infiltration • Malignancy • Infection
What are consequences of untreated DI?
Severe dehydration
Very high sodium levels ‘hypernatraemia’
Reduced consciousness, coma and death
Cranial DI responds brilliantly to synthetic vasopressin
Desmopressin nasal spray, tablets or injection
Very important to understand this condition
What is pituitary apoplexy?
‘Apoplexy’ is the old-fashioned word for stroke Sudden vascular event in a pituitary tumour
Bleeding within tumour ‘haemorrhage’
Blood supply cut off ‘infarction’
Describe the clinical presentation of pituitary apoplexy?
Sudden onset headache
Double vision
Visual field loss
Cranial nerve palsy
Hypopituitarism cortisol deficiency most dangerous
Apoplexy needs prompt diagnosis and treatment
