Flashcards in Therapeutics of endocrine disease Deck (48)
What are the two parts of the pituitary gland?
adenohypophysis (anterior) and neurohypophysis (posterior) = connected to the hypothalamus via the H-H tract
What are the different cell types of the anterior lobe of the pituitary and what hormones are released and what hypothalamic hormones act on it?
Somatotrophs - GHRH/Somatostatin (inhibitory) => somatotrophin
Lactotrophs - TRH/dopamine (inhibitory) => prolactin
Corticotrophs - CRH =>ACTH
Gonadotrophs - GnRH => FSH/LH
Thyrotrophs - TRH =>TSH
What are the hormones released from the posterior lobe?
ADH and oxytocin - they are produced in the hypothalamus
What are the different types of pituitary disease?
hyper-secretion - usually due to a pituitary tumour or rarely hypothalamic disease or ectopic release of hormone
if macroadenoma hypersecretion of one hormone may be associated with hyposecretion of others (mass effects)
Also important to be aware of local effects e.g. optic chiasm compression
Are there differences between malignant and benign tumours?
malignant pituitary tumours are very rare but are difficult to distinguish from benign ones
What pituitary disease is associated with ACTH?
cushing's- raised cortisol
What pituitary disease is associated with GH?
Acromegaly - raised GH and IGF-1
What pituitary disease is associated with LH/FSH?
Gonadotrophisome - raised oestrogen / testosterone
What pituitary disease is associated with TSH?
TSH-oma - thyrotoxicosis
What pituitary disease is associated with prolactin?
prolactinoma - galactorhoea, amenorrhoea, headache
What is acromegaly and what are the symptoms?
excess of GH and therefore IGF-1
Main symptoms: abnormally large hands and feet, large prominent facial features, enlarged tongue, abnormally tall height (gigantism before puberty)
other symptoms: headaches, joint pain
What are the signs for acromegaly?
coarse facial features
nerve entrapment - carpal tunnel syndrome (compression of nerve in the wrist causing numbness and weakness of the hands)
What is Cushing's disease and what are the signs?
caused by a pituitary adenoma secreting ACTH causing excess cortisol
- round, plethoric face
- weight gain - very rapid and leads to striae
- striae - >1cm broad, pruple and red trans-abdominal
- thin skin, easy bruising
- mood disturbances
Which pts can cushing's pts be confused with?
obese pts just on examination
What is the treatment for cushing's pts?
usually pituitary surgery - esp if seen on CT
medical treatment to reduce cortisol production = metyrapone or ketoconazole (inhibit adrenal enzymes)
may also try somatostatin analogues
need to monitor cortisol levels
can be difficult to get the right balance
if untreated prognosis is the same as a malignant disease
How do you treat prolactinomas?
treat medically rather than surgically
- dopamine agonists e.g. bromocriptine (SA) or cabergoline (LA) highly effective = restore fertility, tumour shrinkage
some may be able to come off treatment
What are the side effects of treatment for prolactinomas?
nausea and occasionally psychosis or movement disorders
by being careful when these medications are taken we can control these SEs (same as in PD)
small theoretical risk of cardiac valve problems - need regular echocardiography
What are the treatments for pituitary tumours?
- trans-sphenoidal or trans-frotnal craniotomy (if too big for TSS) - done if tumour is growing or giving mass effects
- effect is delayed but it causes shrinkage - risk of inducing hypopituitarism and potentially a risk of inducing malignancy
What are non-functional tumours?
those that do not secrete a pituitary hormone that leads to a clinical syndrome
most pituitary tumours are non-functional
What are the conditions associated with hypopituitarism ?
LH/FSH deficiency - hypogonadism, infertility = HRT/OCP, testosterone, assisted conception
TSH deficiency - hypothyroidism = levothyroxine
ACTH deficiency - adrenal insufficiency = hydrocortisone
GH deficiency - reduced growth in children - Growth hormone subcut - dont tend to give to adults, unless specific need (mental health)
ADH deficiency - diabetes inspidus = desmopressin
What does ADH do?
ADH secreted in response to increases in plasma osmolality (also important for vol regulation)
Acts on collecting ducts - (intrinsically impermeable to water), therefore ADH stimulates production of AQPs and their incorporation into the walls of collecting ducts
Allows reabsorption of "free" water from tubular fluid
ADH levels rise in water deprivation
What is diabetes insipidus?
can be secondary to generalised pituitary disease or isolated/idiopathic
What do you get with diabetes insipidus ?
polyuria e.g.>3L/day and polydipsia
hypernatraemia and increased serum osmolality - occurs if you aren't replenishing what's lost
How is diabetes insipidus diagnosed?
having a dilute urine in the context of a concentrated plasma
needs specialist (and dangerous) test to diagnose - have to water deprive and measure urine osmolality
How is diabetes insipidus treated?
oral or intranasal desmopressin (ADH analogues) if the cause is central
overuse can lead to hyponatraemia
What is SIADH and what does it cause?
syndrome of inappropriate ADH release = make too much ADH
- common cause of hyponatraemia = excessive water retention relative to sodium => low serum sodium in the absence of volume depletion
- inappropriately high urinary sodium loss and urine osmolality greater than serum as they are concentrating urine too much
What is the treatment for SIADH?
water restriction, not a normal saline infusion
significant risks if hyponatraemia is corrected too rapidly and therefore we should not >8mmol/L per 24 hours correction of sodium
What happens if you do correct sodium levels too quickly?
risk of pontine demyelination - risk is increased if the patient has a poor diet or liver disease
What are the causes of SIADH?
- lung cancer (small cell)
- head injury