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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
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which is the best test for GH excess
dynamic: OGTT (glucose inhibits GH release normally)
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whats the best test for prolactin excess?
prolactin measurement
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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
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what is hypogonadotrophic hypogonadism?
deficiency of LH or FSH (the gonadotrophs) causing gonadal failure
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what pattern is LH secreted in? when is it pathological?
- LH secreted in pulses.
- continuous LH secretion is abnormal and results in gonadal suppression
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what is the function of LH?
- stimulates testosterone production
- causes ovulation in ovary, hence progesterone production
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what is the function of FSH?
stimulates spermatogenesis, follicle in the ovary and hence oestradiol
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what are the LH and FSH levels pre-puberty?
low or undetectable
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what happens to gonadotrophin levels in puberty?
increase therefore increase gonadal activity and steroid output
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what causes menopause?
running out of follicles in ovary
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what is the other name for menopause at an early age e.g. < 40?
premature ovarian failure
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What causes feedback inhibition of TSH?
T3
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why do we measure the free thyroid hormones?
avoids problems with the protein binding in the serum, and free are active ones
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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
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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
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what is struma ovarii?
ovarian teratoma containing thyroid tissue
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which blood test is used to detect recurrence of papillary or follicular carcinoma after total thyroidiectomy?
thyroglobulin
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which tumour marker can be used to screen family members for medullary carcinoma of thyroid?
calcitonin (as its from parafollicular cells)
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what restricts using HbA1C for glycaemic control?
anything that has altered normal red cell lifespan and blood transfusions (as not own RBCs!)
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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
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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
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what is target HbA1C?
lower than 6%
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where is the adrenal cortex originally from?
mesodermal origin from urogenital ridge
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where is adrenal medulla originally from?
neuro-ectodermal origin
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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
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which one of the adrenal cortex hormones is independent of ACTH and what control is it under?
- aldosterone
- regulated by serum potassium and renin-angiotensin
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what is the commonest cause of cushing's syndrome?
iatrogenic giving steroids
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which are the 3 most common non pituitary neoplasms that produce ectopic ACTH?
- lung cancer
- medullary thyroid cancer
- thymomas
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what are the causes of secondary hyperaldosteronism?
- increased renin release
- renal ischaemia: RAS
- chronic oedema: nephrotic syndrome, CCF
- renin producing neoplasms
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what are the main features of addisons disease?
- low Na so hypotension, collapse
- high K so cardiac arrhythmias
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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
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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
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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
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what are causes of chronic adrenal insufficiency?
- autoimmune
- metastasis e.g. from breast
- infection: TB
- AIDS
- amyloidosis
- sarcoidosis
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which test do you do for addisons?
short ACTH stimulation test (synacthen test)
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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
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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
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which HLA is hashimotos associated with?
B8
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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
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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
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what is the ECG of hypocalcaemia?
long QT interval
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what is ECG of hypercalcaemia?
short QT interval
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if the calcium is low and phosphate is raised, what are the causes of low calcium?
- chronic renal failure
- hypoPTH or pseudohypoPTH
- acute rhabdo
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if calcium is low and phosphate is low or normal, what are the causes of low calcium?
- osteomalacia: high alkaline phosphatase
- over hydration
- pancreatitis
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which acid base disturbance do you get symptoms of low calcium and why?
resp alkalosis as albumin binds to H+
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what is hypothyroidism WITHOUT a goitre likely to be due to?
primary myxoedema or atrophic thyroiditis
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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)
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who is radioablation CI in?
pregnany and breast feeding
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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
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which stain is used in medullar carcinoma of thyroid and why?
- congo red
- as get amyloid deposits which are calcitonin
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