if you had to do a static test for GH excess, what would it be?
- IGF-1 levels
- not GH as it is pulsatile
- but it makes IGF-1
which is the best test for GH excess
dynamic: OGTT (glucose inhibits GH release normally)
whats the best test for prolactin excess?
if you see a raised prolactin level, what do you have to exclude first?
macroprolactin: binding of prolactin to Ig to reduce its clearance so leaving more in the circulation
what is hypogonadotrophic hypogonadism?
deficiency of LH or FSH (the gonadotrophs) causing gonadal failure
what pattern is LH secreted in? when is it pathological?
- LH secreted in pulses.
- continuous LH secretion is abnormal and results in gonadal suppression
what is the function of LH?
- stimulates testosterone production
- causes ovulation in ovary, hence progesterone production
what is the function of FSH?
stimulates spermatogenesis, follicle in the ovary and hence oestradiol
what are the LH and FSH levels pre-puberty?
low or undetectable
what happens to gonadotrophin levels in puberty?
increase therefore increase gonadal activity and steroid output
what causes menopause?
running out of follicles in ovary
what is the other name for menopause at an early age e.g. < 40?
premature ovarian failure
What causes feedback inhibition of TSH?
why do we measure the free thyroid hormones?
avoids problems with the protein binding in the serum, and free are active ones
what is cretinism?
- severely stunted physical and mental growth due to untreated neonatal hypothyroidism
- so all neonates now screened for high TSH
what is the natural history of hashimotos thyroiditis?
- temporary hyperthyroidism
- then primary hypothyroidism from destruction of gland tissue
what is de quervains thyroiditis? and treatment?
- acute severe hyperthyroidism with a painful thyroid
- caused by viral
- young middle aged women
- fever, high ESR
- low isotope uptake on scan
- Rx: NSAIDs
what is struma ovarii?
ovarian teratoma containing thyroid tissue
which blood test is used to detect recurrence of papillary or follicular carcinoma after total thyroidiectomy?
which tumour marker can be used to screen family members for medullary carcinoma of thyroid?
calcitonin (as its from parafollicular cells)
what restricts using HbA1C for glycaemic control?
anything that has altered normal red cell lifespan and blood transfusions (as not own RBCs!)
is OGTT completely safe? why?
no if baseline glucose is really high then may get diabetic emergency DKA or HONK as body cannot deal with high glucose load
if a diabetic pt has sickle/thal then which test is used to check their glycaemic control?
fructosamine. but it has a shorter term glycaemic control than HbA1C
what is target HbA1C?
lower than 6%
where is the adrenal cortex originally from?
mesodermal origin from urogenital ridge
where is adrenal medulla originally from?
in the adrenal cortex, what is the name of each zone and what does it make?
- zona glomerulosa: aldosterone
- zona fasciculata: cortisol and corticosterone
- zona reticularis: androgens
which one of the adrenal cortex hormones is independent of ACTH and what control is it under?
- regulated by serum potassium and renin-angiotensin
what is the commonest cause of cushing's syndrome?
iatrogenic giving steroids
which are the 3 most common non pituitary neoplasms that produce ectopic ACTH?
- lung cancer
- medullary thyroid cancer
what are the causes of secondary hyperaldosteronism?
- increased renin release
- renal ischaemia: RAS
- chronic oedema: nephrotic syndrome, CCF
- renin producing neoplasms
what are the main features of addisons disease?
- low Na so hypotension, collapse
- high K so cardiac arrhythmias
what are the 2 main difference between primary and secondary adrenal insufficiency?
- hyperpigmentation in primary
- no marked hypoNa or hypotension in secondary as aldosterone is ACTH independent and secondary is due to a hypothalamus or hypopituitary problem
what is waterhouse-friderichson syndrome, which endocrine problem does it cause?
- it is in meningococcal (or staph/strep) sepsis get haemorrhage into the adrenal glands. also see petechiae in the skin
- see most in infants
what are causes of acute adrenal insufficiency?
- rapid withdrawal of long term steroid therapy
- perinatal haemorrhagic necrosis
- post partum infarction
- adrenal haemorrhage
- waterhouse-friderich syndrome
- traumatic necrosis
what are causes of chronic adrenal insufficiency?
- metastasis e.g. from breast
- infection: TB
which test do you do for addisons?
short ACTH stimulation test (synacthen test)
what are causes of secondary adrenal insufficiency? and distinguishing feature from primary?
- rapid withdrawal of long term steroid use
- rare: hypothalamic and hypopituitary disease leading to reduced ACTH
- no hyperpigmentation as no excess ACTH
what is the most common cause of goitre?
- iodine deficiency due to decreased intake of iodine
- so lack of thyroid hormones, so high TSH so hyperplasia of thyroid follicles and multinodular goitre
which HLA is hashimotos associated with?
what are the symptoms of hypercalcaemia?
- GI: abdo pain, vomit, constipation, anorexia,
- general: wt loss, tired, weak, confusion, polydipsia, polyuria
- Cardio: hypertension, decreased QT interval on ECG, cardiac arrest
what are the symptoms of hypocalcaemia?
- tetany, depression, perioral paraesthesiea, carpo-pedal spasm
- Trousseau's sign: BP cuff around brachial artery get carpo-pedal spasm
- Chvostek's sign: tap over parotid facial nerve and muscles twitch
what is the ECG of hypocalcaemia?
long QT interval
what is ECG of hypercalcaemia?
short QT interval
if the calcium is low and phosphate is raised, what are the causes of low calcium?
- chronic renal failure
- hypoPTH or pseudohypoPTH
- acute rhabdo
if calcium is low and phosphate is low or normal, what are the causes of low calcium?
- osteomalacia: high alkaline phosphatase
- over hydration
which acid base disturbance do you get symptoms of low calcium and why?
resp alkalosis as albumin binds to H+
what is hypothyroidism WITHOUT a goitre likely to be due to?
primary myxoedema or atrophic thyroiditis
if carbimazole does not work in Graves, what are the next 2 options?
- radioactive ablation using I131
- surgery: subtotal thyroidectomy (become hypo and RLN damage so hoarse voice)
who is radioablation CI in?
pregnany and breast feeding
if you see orphan-annie eye nuclei, what does that indicate?
papillary carcinoma of thyroid gland - all the colour part is pushed to the edge and the central part is clear
which stain is used in medullar carcinoma of thyroid and why?
- congo red
- as get amyloid deposits which are calcitonin