Pituitary Flashcards
What hormones are secreted by the anterior pituitary?
FLAT PIG FSH LH ACTH TSH PRL MSH GH
What is hormones are secreted by the posteriorly pituitary?
ADH vasopressin
Oxytocin
Why does hypopituitarism present earlier in pre-menopausal women?
Since get secondary amenorrhea
Hypopituitarism is a deficiency of 1 or more hormones produced by the pituitary gland - true or false
True
What are trophic hormones?
Produced by anterior pituitary
What is the commonest cause of hypopituitarism?
Pituitary adenoma
How does a pituitary adenoma cause hypopituitarism?
Pituitary adenoma secretes excess of 1 type of hormone which causes deficiency of other hormones
Name 2 iatrogenic causes of hypopituitaism
Head irradiation
During surgery
What is a macro and microadenoma?
Micro <1cm
Macro >1cm
What visual field defect can a pituitary adenoma cause?
Bitemporal hemianopia
What visual field defect can a craniopharyngioma cause?
?
In hypopituitarism, what is the general order for loss of pituitary hormone function?
GGAT
Gonadotrophins > GH > ACTH > TSH
What is Sheehan’s syndrome?
Vascular cause of hypopituitarism - to severe hypotension eg in obstetric blood loss
What is pituitary apoplexy?
Infarction or haemorrhage of pituitary gland
TB, syphilis and AIDS can all cause hypopituitarism - true or false
True
A craniopharyngioma can cause hypopituitarism - true or flase
True (compression)
When investigating hypopituitarism, measure pituitary hormones + those that they stimulate. Which 2 hormones are less useful to measure since they have variable release?
Cortisol, growth hormone
What type of imaging is best to visualise the pituitary?
MRI
When investigating hypopituitarism, measure pituitary hormones + those that they stimulate. Which hormones are measured?
TSH, fT4, LH/FSH, estrogen/ testosterone
all low
ITT insulin tolerance: give _____, causes _____, should see rise in _____ + _____
ITT insulin tolerance: give INSULIN, causes HYPOGLYCAEMIA, should see rise in CORTISOL + GROWTH HORMONE
ACTH-oma is also known as what?
Cushing’s disease
GH-oma is also known as what?
Acromegaly
Acromegaly causes gigantism in children if onset before _____
epiphyseal fusion
What effect does Cushing’s disease have on
- face shape
- mood
- energy levels
- body composition
- BMI
- glucose
- hair
- menstruation
Moon face Depression Low energy Lemon on sticks High BMI Hyperglycaemia Thin hair / hirsutism Oligomenorrhea
(Also: frequent infections, poor concentrations, buffalo hump, poor wound healing, hypertension)
What is seen on an ABG in Cushing’s disease?
Hypokalaemic metabolic alkalosis
What features of Cushing’s disease are specific and help differentiate it from obesity?
Osteoporosis
Proximal myopathy
Frontal balding
Striae stretch marks (purple)
Name 3 causes of Cushing’s syndrome
Cushing’s disease
Exogenous steroids
Adrenal tumour/hyperplasia
Exogenous ACTH from SCLC
What is the initial investigations for Cushing’s?
Low dose overnight dexamethasone suppression test
What is the low dose overnight dexamethasone suppression test?
Cortisol is too high - so try and suppress it
Giving dexamethasone should stop (suppress) cortisol production)
Give 1mg dexamethasone overnight - then measure in morning cortisol - if cortisol still high requires further testing
Patients without Cushing’s will have their morning cortisol spike suppressed
Pituitary adenoma can cause a headache - true or false
It can do
What test is used to differentiate between Cushing’s and pseudo-Cushing’s?
Insulin stress test
The low dose 1mg dexamethasone test tests for presence of Cushing’s syndrome and the high dose dexamethasone test localises the pathology of Cushing’s syndrome - true or false
True (i think)
What is the high dose 8mg dexamethasone suppression test?
Give higher dose of dexamethasone and then measure cortisol + ACTH
Following high dose 8mg dexamethasone suppression test in ectopic ACTH secretion - are cortisol and ACTH suppressed?
Cortisol - not suppressed
ACTH - not suppressed
Following high dose 8mg dexamethasone suppression test in Cushing’s disease - are cortisol and ACTH suppressed?
Cortisol - suppressed
ACTH - suppressed
(Pituitary secreting excess ACTH, so when give
Following high dose 8mg dexamethasone suppression test in an adrenal adenoma/ hyperplasia - are cortisol and ACTH suppressed?
Cortisol - not suppressed
ACTH - suppressed
What is the commonest pituitary adenoma?
Prolactinoma
How is a prolactinoma diagnosed?
Measure PRL > MRI
How is a micro v maro prolactinoma differentiated?
MRI 6mth apart
What is the 1st line management of a prolactinoma?
Dopamine agonist cabergoline
Can acromegaly cause hepatosplenomegaly?
Yes
What is the first line investigation for acromegaly?
Measure IGF-1
OGGT oral glucose tolerance test
(glucose should suppress GH, +ve if stays same),
(then MRI pituitary)
What is the first line management of acromegaly?
Trans-sphenoidal surgery
2nd line somatostatin analogue octreotide
What are the 2 types of diabetes insipidus?
Cranial and nephrogenic
What is the basic pathology of diabetes insipidus?
Too little ADH
What drug causes nephrogenic diabetes insipidus?
Lithium
What is the presentation of diabetes insipidus?
Polydipsia, polyuria
In diabetes insipidus, is plasma osmolality high or low? Is urine osmolality high or low?
Low urine osmolality (very dilute urine)
High plasma osmolality (high plasma Na/urea)
What is the first line investigation for diabetes insipidus?
Water deprivation test
Ambiguous results on a water deprivation test suggest what cause?
Psychogenic polydipsia
What is the management of cranial diabetes insipidus?
Synthetic ADH vasopressin
What is the management of nephrogenic diabetes insipidus?
Treat/stop cause
For DI, in a positive water deprivation test result, following water deprivation urine osmolality _____ + plasma osmolality _____. Then give exogenous ____, in cranial DI urine osmolality _____ and in nephrogenic DI urine osmolality ______.
For DI, in a positive water deprivation test result, following water deprivation urine osmolality STAYS SAME + plasma osmolality INCREASES. Then give exogenous ADH, in cranial DI urine osmolality INCREASES and in nephrogenic DI urine osmolality STAYS LOW
Is plasma osmolality low or high in SIADH?
Low plasma osmolality
lower than urine osmolality
Is sodium low or high in SIADH
Low sodium
What is the presentation of SIADH?
Confusion, lethargy, muscle cramps, N&V, oliguria, symptoms of underlying cause
What malignancy may cause paraneoplastic SIADH?
SCLC
Loads of others too
Can pneumonia cause SIADH?
Yes
What is the first line management of SIADH?
Fluid restriction
What drug can be used in the management of severe SIADH?
Tolvaptan
Why must sodium be corrected slowly in SIADH
To prevent central pontine myelinolysis
