Endocrine Flashcards
(126 cards)
what is the cause of majority of acromegaly cases?
pituitary adenoma
what are the features of acromegaly?
coarse facial appearance, spade-like hands, big feet.
large tongue, prognathism, interdental spaces
excessive sweating and oily skin: caused by sweat gland hypertrophy
features of pituitary tumour: hypopituitarism, headaches, bitemporal hemianopia
raised prolactin in 1/3 of cases → galactorrhoea
hypertension
diabetes (>10%)
cardiomyopathy
colorectal cancer
how is acromegaly investigated?
Serum IGF-1 levels (when first suspected and also used for monitoring)
oral glucose tolerance test (OGTT) - confirms if IGF1 is raised
pituitary MRI
how does oral glucose tolerance test confirm acromegaly?
give glucose, if GH does not become supressed to <1 , then confirms diagnosis
how is acromegaly treated?
Trans-sphenoidal surgery as first line If a pituitary tumour is inoperable or surgery unsuccessful then medication may be indicated: somatostatin analogue (octreotide) pegvisomant dopamine agonist (bromocriptine)
How does a somatostatin analogue work in acromegaly?
inhibits release of GH
What is the mechanism of pegvisomant?
GH receptor antagonist - prevents dimerization of the GH receptor
once daily s/c administration
what are the acute phase proteins?
during inflammation/infection liver increases production of acute phase proteins…
CRP, procalcitonin, ferritin, fibrinogen, alpha-1 antitrypsin, caeruloplasmin, serum amyloid A & P , haptoglobin and complement
which proteins are decreased during acute phase response?
albumin transthyretin (formerly known as prealbumin) transferrin retinol binding protein cortisol binding protein
what is the function of CRP?
binds to phosphocholine in bacterial cells and on those cells undergoing apoptosis. In binding to these cells it is then able to activate the complement system.
what is the commonest cause of hypoaldrenalism? what is this called?
Autoimmune destruction of the adrenal glands
Addisons - both cortisol and aldosterone reduced
what are the features of addisons?
lethargy, weakness, anorexia, nausea & vomiting, weight loss,
‘salt-craving’
hyperpigmentation (especially palmar creases) hypotension, hypoglycaemia
hyponatraemia and hyperkalaemia may be seen
vitiligo, loss of pubic hair in women,
crisis: collapse, shock, pyrexia
other than addisons what are the other causes of hypoadrenalism?
tuberculosis metastases (e.g. bronchial carcinoma) meningococcal septicaemia (Waterhouse-Friderichsen syndrome) HIV antiphospholipid syndrome
Secondary causes pituitary disorders (e.g. tumours, irradiation, infiltration)
Exogenous glucocorticoid therapy
how is addisons disease diagnosed?
ACTH stimulation test (short Synacthen test). Plasma cortisol is measured before and 30 minutes after giving Synacthen 250ug IM.
Adrenal autoantibodies such as anti-21-hydroxylase may also be demonstrated.
If an ACTH stimulation test is not readily available then sending a 9 am serum cortisol can be useful:
> 500 nmol/l makes Addison’s very unlikely
< 100 nmol/l is definitely abnormal
100-500 nmol/l should prompt a ACTH stimulation test to be performed
what are the electrolyte abnormalities in addisons?
hyperkalaemia
hyponatraemia
hypoglycaemia
metabolic acidosis
what are the causes of an addisonian crisis?
acute exacerbation of chronic hypoadrenalism e.g. surgery or infection
OR
Sudden loss of adrenal - adrenal haemorrhage eg Waterhouse-Friderichsen syndrome (fulminant meningococcemia)
OR
steroid withdrawal
how is addisonian crisis managed?
hydrocortisone 100 mg im or iv
1 litre normal saline infused over 30-60 mins or with dextrose if hypoglycaemic
continue hydrocortisone 6 hourly until the patient is stable.
No fludrocortisone is required because high cortisol exerts weak mineralocorticoid action
oral replacement may begin after 24 hours and be reduced to maintenance over 3-4 days
causes of raised ALP (Alanine phosphatase)?
liver: cholestasis, hepatitis, fatty liver, neoplasia
Paget’s
osteomalacia
bone metastases
hyperparathyroidism
renal failure
physiological: pregnancy, growing children, healing fractures
how can the causes of raised ALP be differentiated?
Calcium levels..
if high ALP and high CA - bone mets/ hyperparathyroid
if high ALP and low Ca - osteomalacia/renal failure
define primary amenorrhoea.
failure to establish menstruation by 15 years of age in girls with normal secondary sexual characteristics (such as breast development), or by 13 years of age in girls with no secondary sexual characteristics
define secondary amenorrhoea
Cessation of menstruation for 3-6 months in women with previously normal and regular menses, or 6-12 months in women with previous oligomenorrhoea
what are the causes of primary amenorrhoea?
gonadal dysgenesis (e.g. Turner’s syndrome) - the most common causes
testicular feminisation
congenital malformations of the genital tract
imperforate hymen
functional hypothalamic amenorrhoea (e.g. secondary to anorexia)
congenital adrenal hyperplasia
what are the causes of secondary amenorrhoea?
hypothalamic amenorrhoea (e.g. secondary stress, excessive exercise)
polycystic ovarian syndrome (PCOS)
hyperprolactinaemia
thyrotoxicosis / hypothyroid
premature ovarian failure
Sheehan’s syndrome
Asherman’s syndrome (intrauterine adhesions)
how is amenorrhoea investigated?
Exclude pregnancy with urinary or serum bHCG
full blood count, urea & electrolytes, coeliac screen, thyroid function tests
gonadotrophins
low levels indicate a hypothalamic cause where as raised levels suggest an ovarian problem (e.g. Premature ovarian failure)
raised if gonadal dysgenesis (e.g. Turner’s syndrome)
prolactin
androgen levels - raised levels may be seen in PCOS
oestradiol