endocrine Flashcards
Describe the layers of the adrenal glands and what each layer produces?
Endogenous?
Exogenous?
Blockers?
Adrenal cortex - steroids hormones
- Glucocorticloids - cortisol - sugar control
- Mineralocorticoids - aldosterone - salt and water
Exogenous glucocorticoids - dexamethasone, betamethasone
- Blocked by
Exogenous mineralocorticloids -
fludrocortisone
Adrenal medulla
- Adrenaline, noradrenalineby spironolactone and eplenerone
How do you define delayed puberty in girls?
How about in boys?
What is precocious puberty?
No breast development by age 13
No testicular development or <4ml by age 14
Precocious puberty - development of secondary sexual characteristics before age 8
What are the causes of raised prolactin?
Physical:
- Pituitary tumour
Drugs:
- Antipsychotics
- SSRIs
- opiates
- Ranitidine - H2 blockers
Endocrine:
- Hypothyroidism
- Lactation
- Pregnancy
- Acromegaly
Medical conditions:
- Liver failure
- Renal disease
- PCOS
Describe the cells present in the ovaries and their various functions
Theca cells
- Produce androgens but cant convert to oestradiol
- LH stimulates production of androgens
- LH also stimulates contraction of the smooth muscle layer of the theca externa which causes the mature oocyte to pop.
Granulosa cells
- FSH signals granulosal cells to produce aromatase which in turn converts the androgens to oestradiol.
- Produce progesteron
Where is glucagon produced?
What does it cause?What are the stimulants of glucagon?
What are the inhibitors of glucagon?
Alpha cells of pancreas
Increases blood glucose
Increases glycogenosysis
Increase gluconeogenesis
Stimulants
- Hypoglycaemia
- Adrenaline
- Actylcholine
- Arginine/alanine
- Cholecystokinin
Inhibits:
- Insulin
- Raised urea
- Somatostatin
- keto-acids
What happens in pregnancy with:
- TSH
- T3/T4
Decreased TSH (remember the limits of normal go down in pregnancy)
Increase T3/T4 - but gradually go down a bit from 1-3 trimester
What is the typical finding on an FBC with addisons disease?
eiosinophilia - dont know why
Addisons disease.
What is it?
Causes?
Symptoms/signs?
Blood test results?
Treatment?
Primary adrenal insufficiency
Causes:
- Autoimmune adrenalitis (most common)
- Secondary - low ACTH from pituitary
- Tertiary - low CRH from hypothalamus
Symptoms:
- Fatigue
- Darkening of the skin
- Weight loss
- Hypotension
- Myalgia/arthralgia
Bloods:
- High K
- Low Na
- eiosinophilia
- Metabolic adicosis
- Hypoglyaemia
Which hormones are structurally similar to TSH
What other group is similar?
FSH, HCG, LH
Prolactin, GH, human placental lactogen
What are the levels for:
- Osteopenia
- Ostoporosis
- Severe osteoporosis
Osteopnia -1 to -2.5
Osteoporosis <-2.5
Severe osteoporosis <-2.5 with fragility fracture
Fragility fracture: NOF, foosh, spine, proximal humerus
How does oxytocin stimulate the contraction of the uterus?
Ultimately needs to release intracellular calcium. Triggers this with activating phospholipase C to produce IP3 which then causes release of the calcium
Inhibitors of contractions:
- cAMP
- Protein kinase A
What is the common precursor molecule for creation of androgens
cholesterol
What conditions lead to an increase in SHBG?
What is the function of SHBG
In general, conditions causing weight loss lead to an increased SHBG e.g. liver cirrhosis
In contrast, weight gain –> lower SHBG
- PCOS
- Hypothyroidism
- Cushings
- Anabolic steroids use
SHBG
- Binds 70% of testosterone
- Other 20-30% bound to albumin
- Approx 1% unbound
What is the first line investigation for addisons?
U&E
AM cortisol
After this there is a place for the short synacthen test
