Endocrinology Flashcards
how do beta 2 agonists work?
bind beta 2 receptors, mimicking action of catecholamines
relax smooth muscle in bronchial tree [broncho-dilation]
why can a pituitary tumour cause vision problems?
optic chiasm lies adjacent to pituitary gland/pituitary
which types of drugs can cause medication induced diabetes?
corticosteroids thiazide diuretics beta blockers antipsychotics statins
examples of diseases that cause “endocrine diabetes”
acromegaly
cushings
Fasted state hormone in glucose regulation
Glucagon
Fed state hormone in glucose regulation
Insulin
Alpha cells of pancreas produce..
Glucagon
Beta cells pancreas produce..
Insulin
Where do glycogen conversion to glucose + gluconeogenesis occur
Liver
how do cortisol levels vary during the day?
high in the morning
decrease during the day
what hormones [produced by the hypothalamus] are secreted by the posterior pituitary
oxytocin
ADH [vasopressin]
describe action of ADH
distal tubule H2O reabsorption [water retention]
to dilute the circulation/^blood vol
actions of oxytocin
breast milk production
labour contractions
ACTH acts on the..
adrenal cortex
which hormone continuously inhibits prolactin?
dopamine
what is Grave’s disease + its cause
autoimmune thyroid disorder > hyperthyroidism
IgG antibodies bind to TSH receptor + stimulate thyroid hormone production + cause diffuse smooth enlargement
2 types of autoimmune thyroiditis
Hashimoto’s [goitre]
atrophic [shrunken]
treatment of thyroid malignancy
thyroidectomy
neck dissection for lymph nodes
radioactive iodine
asymptomatic thyroid nodules that increase in size, become hard and irregular may suggest what pathology?
carcinoma
treatment of primary hypothyroidism
levothyroxine
describe thyroid hormone axis
hypothalamus > TRH (thyrotropin-releasing)
pituitary > TSH (thyroid-stimulating)
thyroid > T4 [+some T3]
in circulation, T4-> more active T3
describe the hormone axis that leads to testosterone or progesterone/oestrogen release
hypothalamus > GnRH (gonadotropin-releasing)
pituitary > LH, FSH
testes > testosterone
ovaries > progesterone, oestrogen
hormone axis that leads to cortisol release
hypothalamus > CRH (corticotropin-releasing)
pituitary > ACTH (adrenocorticotropic)
adrenal cortex > cortisol
growth hormone hormone axis
hypothalamus > GHRH (growth-hormone releasing)
pituitary > GH
liver > IGF1 (insulin-like growth factor)
describe the pathway that leads to prolactin inhibition
hypothalalmus > dopamine (-ve action on pituitary)
pituitary inhibited from producing prolactin
action of somatostatin on pituitary
negative action preventing release of growth hormone
what would levels of TSH and T4 look like in hypothyroid disease?
low T4
high TSH
what would levels of TSH and T4 look like in hypopituitary disease?
low/norm TSH
low T4
what would levels of TSH and T4 look like in Grave’s disease?
high T4
low TSH [negative feedback]
what would TSH and T4 levels look like in patients with genetic hormone resistance [where pituitary doesn’t respond to -ve feedback]?
high TSH
high T4
describe levels of LH/FSH and testosterone in a male patient with primary hypogonadism
low testosterone
high LH/FSH
describe levels of LH/FSH and testosterone in a male pateint with hypopituitary
low testosterone
norm/low FSH/LH
describe levels of LH/FSH and testosterone in a male pateint with anabolic steroid use
low testosterone
suppressed LH/FSH
(steroids inhibit pathway)
describe levels of LH/FSH and oestradiol in female patient with hypopituitary.
& periods?
norm/low LH/FSH
low oestradiol
+ amenorrhoea
describe levels of LH/FSH and oestradiol in female patient with primary ovarian failure [or menopause]
high LH/FSH
low oestradiol
describe levels of ACTH and cortisol in patient with primary adrenal insufficiency
low cortisol
high ACTH
how does patient with primary adrenal insufficiency respond to synacthen test
poor response
what is the synacthen test?
patient given synacthen [ACTH]
test for cortisol response
describe levels of ACTH and cortisol in patient with hypopituitary.
low cortisol
low/norm ACTH
what hormone do you measure to investigate growth hormone pathway problems & why?
IGF-1
GH is pulsatile/ fluctuates so not useful
[also GH stimulation test used]
and OGTT for acromeg
how is prolactin measured?
phlebotomy
BUT stress hormone! so may be raised [white coat]
so can use cannula and take blood over 1 hr [should decrease if raised due to stress]
a benign pituitary adenoma may put pressure on what in the cavernous sinus??
cranial nerves 3,4,5
main symptom of benign pituitary adenoma causing raised intracranial pressure
headache
a benign pituitary adenoma can erode the sphenoid bone causing leakage of what?
CSF
what sort of visual field loss is caused by benign pituitary tumour pressing on optic chiasm?
bitemporal hemianopia
physical features of hypopituitarism
pale
no body hair
central obesity
reproductive related problems in women with hypopituitarism
infertility
amenorrhoea
what causes cushings DISEASE?
pituitary adenoma > excess cortisol
symptoms of a prolactin microadenoma [of lactotroph cells]
unovulation > infertility galactorrhoea (men&women) amenorrhoea decreased libido possible visual field defect low testosterone in men
growth hormone disorders of increased GH production before and after epiphysial growth plate fusion?
before: gigantism
after: acromegaly
diagnosis of cushing’s syndrome
dexamethasone suppression test to confirm raised cortisol
causes of cushing’s syndrome other than pituitary adenoma
exogenous steroids e.g. for asthma
ectopic neuroendocrine cell tumours > ACTH
adrenal tumour > cortisol
is ACTH measurement in cushing’s syndrome is +ve, what further diagnostic test would you carry out?
CT/MRI pituitary
is ACTH measurement in cushing’s syndrome is -ve, what further diagnostic test would you carry out?
CT/MRI adrenal
diagnostic test for agromegaly
glucose tolerance test
GH not supressed as it should be
difference between suppression and stimulation tests (when you’d use them)
suppression: for suspected over-production
stimulation: for suspected deficiency
when would you do transphenoidal surgery for non-functioning pituitary tumour?
if threatening eye sight
or progressively increasing in size
diagnosis of prolactinoma
prolactin test
prolactinoma treatment
dopamine agonist
2 types of pituitary adenoma that lead to ^ed prolactin and must be distinguished
prolactinoma > prolactin
adenoma pressing on pituitary stalk & inhibiting dopamine
hyperandrogenism in females, physical features
hirsutism
temporal balding
acne
what types of regulation is the hypothalamus responsible for?
appetite/thirst menstrual thermal regulation sleep stress mood
where are vasopressin + oxytocin produced stored and released from
produced in hypothalamus
stored + reelased from posterior pituitary
name the 5 hormones relased from the anterior pituitary + where they act
LH/FSH > ovaries/testes GH > many tissues TSH > thyroid prolactin > breasts/gonads ACTH > adrenals
DM causes serious micro and macrovascular problems. Give e.g.s of each
micro: nephropathy, neuropathy, retinopathy
macro: stroke, MI, renovascular disease, limb ishaemia
what causes type 1 DM
autoimmune destruction of insulin-secreting pancreatic B cells, leading to insulin deficiency
risk factors for type 2 DM
asian male elderly obesity reduced exercise calorie excess alcohol excess
which had higher genetic influence, type 1 or type 2 DM
type 2
other causes of DM [other than type 1 or 2]
drugs: steroids, anti-HIV, newer antipsychotics
Pancreas: -itis, surgery, CA, trauma, destruction [CF, haemochromatosis].
cushings/acromeg/phaeochromocytoma/^thyroid/pregnancy
Sx of hyperglycaemia
polyuria polydipsia unexplained weight loss visual blurring genital thrush lethargy
general principles of type 2 DM Mx
weight loss, diet, exercise
tablets (mono>dual>triple therapy)
insulin
statin, BP control
footcare
bariatric surgery
DVLA
DVLA w/ regards DM?
patient must inform
don’t drive if they have hypos
describe drugs used in type 2 DM algorithm
monotherapy - metformin dual therapy - metformin + sitagliptin/sulfonylurea/pioglitazone triple therapy GLP analogues insulin
S.E.s of metformin and how you might overcome?
nausea
diarrhoea
abdo pain
change to modified release
what is the risk of binge drinking in DM
delayed hypoglycaemia
[alcohol prevents liver releasing glucose, drinks contain sugar so effect of liver damage not noticed til later when drinks have been digested/metabolised]
what advice do you give to insulin-dependent DM patients during acute illness e.g. flu
don't stop insulin illness can ^ insulin requirement despite reduced food intake maintain calorie intake check BM 4X/day safety net
what can happen at DM insulin injection sites?
infection
lipohypertrophy
how can you manage microalbuminuria in DM
ACE-inhibitor
ARB [sartan]
spironalactone
what 2 DM complication s affect the feet
neuropathy
ischaemia/vascular disease
examination findings in DM neuropathy and in ischaemia
neuropathy: reduced sensation (stockings) absent ankle jerk deformity - [charcot joint, pes cavus, claw toes, rocker bottom sole] swelling
ischaemia: absent pulses, cold, ulcers
DM foot Ix and Mx
xray, Doppler
patient regular examination
podiatry/chiropodist
shoe advice
treat infections e.g. fungal
vascular surgery
main hormonle released from the thyroid gland
T4
which hormone is more active t3 or t4
and how are they formed
t3
t4 from thyroid gland
t3 from t4 conversion
Investigations when hyperthyroid is suspected
T3, T4, TSH
thyroid autoantibodies
what would happen to TSH in hyperthyroidism
low
unless pituitary adenoma [^TSH]
what can happen to TFTs in systemic illness
sick euthyroidism
deranged TFTs - usually everything low
Pt.s who need thyroid fn screening
DM type 1 in 1st trimester + postpartum amiodarone/ lithium downs/ turners/ addisons AF hyperlipidaemia
what imaging can be used for the thyroid?
US
isotope scan
60 yr old male lump on L side of neck wife noticed hoarse voice no weight loss visible thyroid mass w/ no lymph nodes normal TFT Most likely diagnosis? a)graves b)CA c)multinodular goitre d)benign thyroid adenoma
b)CA
[recurrent laryngeal nerve palsy, Pt age]
commonest type of thyroid CA
papillary
Mx of thyroid CA
surgical excision
radioiodine
suppression of TSH using thyroxine
what is the diagnostic significance of positive peroxidase antibodies
autoimmune thyroid disease
how does amiodarone affect thyroid fn
hypo or hyper [hypo is more common]
graves disease - thyroid uptake scan shows what
diffusely ‘hot’ gland due to increased uptake
a single ‘hot’ spot on a thyroid uptake scan suggests what
adenoma
carcinoma
Mx of graves
carbimazole or propylthiouracil
60 yr old into A+E
confusion, weight loss, agitation, sweating.
HR 140, AF
CXR: enlarged heart w/ bibasal pleural effusions. Diffuse shadow in upper mediastinum + neck scar.
Likely diagnosis?
thyroid storm [complicated by hyperthyroid-induced HF]
what do you test for in urine for phaeochromocytoma
24 hr for metanephrines/ metadrenaline
where in the adrenals are phaeochromocytomas found
medulla
phaeochormocytoma age and gender commonest
equal sex incidence
30-50
MEN-2 [multiple endocrine neoplasia] consists of :
phaeo
hyperparathyroidism
medullary thyroid ca
MEN-1 [multiple endocrine neoplasia] consists of :
hyperparathyroidism
pituitary tumour
pancreatic tumour
Mx of phaeo
alpha blockade [phenoxybenzamine] followed by beta blockage [propranolol] to avoid massive catecholamine release during surgery
classic triad of phaeochromocytoma
episodic headache
sweating
tachycardia
2 examples of catecholamines
dopamine
noradrenaline
adrenaline
most common cause of addisons in the developed and worldwide
uk - autoimmunek adrenalitis
worldwide - TB
3 layers of the adrenal cortex from outer to inner and what they produce
glomerulosa - aldosterone
fasciculata - cortisol
reticulata - testosterone
why do addisons patients have hyperkalaemia
no production of glucocorticoids OR mineralocorticoids e.g. aldosterone.
Aldosterone increases K+ secretion