S8 Pituitary Disorders Flashcards
What is the clinical presentation of pituitary tumours?
- visual loss
- headache
- hypo-/hyper-secretion (abnormality in pituitary function)
Why do you get visual field loss when a pituitary tumour grows upwards/superiorly?
It applies pressure on the optic chiasm
Why do you get double vision/pain when a pituitary tumour grows sideways/laterally?
Applies pressure to the nerve that controls eye movements and pain
A pituitary tumour can inhibit the function of the hypothalamic control on the pituitary gland, what does it affect? What is this called?
- no positive control of GH, LH/FSH, TSH or ACTH
- no negative control of prolactin (so prolactin levels increase)
Hypopituitarism
What does growth hormone deficiency lead to in children and adults?
Children - short stature
Adults - reduce quality of life
What does a gonadotropin deficiency result in?
- delayed puberty in children
- loss of secondary sexual characteristic in adults
- loss of periods is an early sign for women
When can gonadotropin deficiency be commonly seen in men?
When using chemotherapy to treat prostate cancer, the drug inhibits testosterone
When can TSH and ACTH deficiencies occur?
They’re a late feature of pituitary tumours
What does TSH deficiency present as?
- low thyroid hormones
- cold
- weight gain
- tiredness
- slow pulse
- low T4
- non-elevated TSH
What does ACTH deficiency present as? What can it result in?
- low cortisol
- tiredness
- dizziness
- low BP
- low sodium
- HPA axis will be affected
Hypoadrenal crisis which is life threatening
Which hormones are usually produced in excess when there’s abnormality in pituitary function?
Which are produced in excess more rarely?
- prolactin
- GH
- ACTH
- TSH
- LH/FSH
What biochemical assessment do you carry out to assess pituitary disease affecting the thyroid axis, gonadal axis and prolactin axis?
A basal blood test
What biochemical assessment do you carry out to assess pituitary disease affecting the HPA axis, GH axis?
A dynamic blood test may be needed
Why does it matter when you do a blood test to asses the HPA axis?
Testing for cortisol levels - levels of cortisol vary throughout the day (usually tested at 9am when levels are at higher levels)
What is a dynamic blood test?
When you activate/suppress a hormonal axis and observe the response
When would you suppress and when would you stimulate in a dynamic assessment of HPA and GH axes?
Stimulate when suspected hormone deficiency
Suppress when suspected hormone excess
What do you stimulate and suppress for a dynamic assessment of the HPA/adrenal axis?
Stimulate adrenals by ACTH (using a synthetic form) or insulin stress test - induce hypoglycaemic stress by giving insulin by IV - usually hypoglycaemic stress should activate the HPA axis
Suppress ACTH axis with steroids
What do you stimulate and suppress for a dynamic assessment of the GH axis?
Stimulate using the insulin stress test (should stimulate GH release)
Suppress using the glucose tolerance test (increase blood glucose as increased blood glucose reduces GH release)
How do you do a radiological assessment of pituitary disease?
Use MRI
What is a bi-temporal hemi-anopia suggestive of?
A pituitary tumour
What is a prolactinoma?
A prolactin-secreting pituitary tumour
When is a tumour considered a macro-adenoma or a micro-adenoma?
Macro-adenoma: more than 1cm
Micro-adenoma: less than 1cm
How are prolactinomas treated?
With tablets, not an operation
What type of drug can you use to shrink a macro-prolactinoma?
A dopamine agonist as dopamine inhibits prolactin
What does prolactin inhibit if it’s present in high levels?
LH secretion
What are the symptoms of hyperprolactinaemia in women?
- menstrual disturbance
- fertility problems
- galactorrhoea (milky discharge from nipple)
What are the symptoms of hyperprolactinaemia in men?
- larger tumours (macro-adenoma)
- may present with mass symptoms such as visual loss
- present later than women as they don’t have periods
- any symptoms of low testosterone are non-specific
How can you tell whether you have disinhibition or a prolactinoma based off of prolactin blood tests?
If less than 5000 it is disinhibition
If more than 5000 it is prolactinoma
What is a non-functioning pituitary adenoma?
Adenoma means there’s no secretion of biologically active hormones or may secrete inactive hormones
How do you treat a prolactinoma?
Use a dopamine agonist (to stimulate D2 receptors) - bromocriptine or cabergoline
What is acromegaly? What can cause acromegaly?
Large extremities e.g. hands and feet
Occurs due to growth hormone excess -
- growth hormone (GH) secreting pituitary tumour
- genetics
What are some long term complications of untreated acromegaly?
- premature cardiovascular death
- increased risk of colonic tumours
- increased risk of thyroid cancer?
- disfiguring body changes that may be irreversible
- hypertension
- diabetes
- unpleasant symptoms
What biochemical tests do you carry out to confirm acromegaly?
- oral glucose tolerance tests - glucose should suppress the GH
How is acromegaly caused by a tumour treated?
- surgical removing of tumour (trans-sphenoid always hypophysectomy)
- reduce GH secretion
- block GH receptor
What is Cushing’s disease?
An ACTH secreting pituitary tumour
How does Cushing’s disease present?
- round pink face
- round abdomen
- skinny with weak arms and legs
- thin skin
- easy bruising
- stretch marks (purple/red) on abdomen
- high blood pressure
- diabetes
- osteoporosis
What is the difference between Cushing’s disease and Cushing’s syndrome?
Disease is due to a pituitary tumour
Syndrome may be caused by other pathologies e.g. adrenal tumour, ectopic ACTH or steroid medication
What is diabetes insipidus? What does it present as?
Not reabsorbing water in the kidneys
Large quantities of pale urine and extreme thirst due to fluid loss
Why does diabetes insipidus occur?
Issues with the posterior pituitary glands secreting vasopressin (ADH) e.g. vasopressin not secreted
What is cranial diabetes insipidus?
What is nephrogenic diabetes insipidus?
A vasopressin deficiency pituitary disease
A vasopressin resistance kidney disease
What pathology can cause cranial diabetes insipidus?
- inflammation
- infiltration
- malignancy
- infection
What are the consequences of untreated diabetes insipidus?
- severe dehydration
- hypernatraemia
- reduced consciousness, coma and death
How is cranial diabetes insipidus treated?
Synthetic vasopressin - nasal spray, tablets or injection
What is pituitary apoplexy?
A stroke caused by a sudden vascular event in a pituitary tumour e.g. bleeding within the tumour (haemorrhage) or blood supply cut off (infarction)
What is the clinical presentation of pituitary apoplexy?
- sudden onset headache
- double vision
- visual field loss
- cranial nerve palsy
- hypopituitarism
A deficiency of which hormone is most dangerous linked to pituitary apoplexy?
Cortisol deficiency
