Cushings Syndrome, hypopituitarism, diabetes insipidus Flashcards
what is cushings syndrome
excess cortisol
what are the effects of too much cortisol
protein loss:
- myopathy: wasting
- osteoporosis: fractures
- thin skin: striae, bruising
altered carbohydrate/ lipid metabolism: diabetes mellitus, obesity (central)
altered psyche: psychosis, depression
what results from excess mineralocorticoid
hypertension, oedema (due to excess mineralocorticoid activity- aldosterone)
what results from excess androgen
virilism, hirsutism, acne, oligo/amenorrhoea
what are the features of cushings
thin skin: bruising, striae
proximal myopathy: difficulty in getting out of chair
frontal balding in women
conjunctival oedema (chemosis)
osteoporosis (usually overweight women dont get osteoporosis)
‘moon face’
intrascapular fat pad
what tests can be done to diagnose cushings
- definitive test= low dose dexamethasone suppression test: 2 day 2mg/ day
cortisol <50 next morning is normal
>130 is definitely cushings
- suppression test- overnight (given at midnight) exogenous oral high dose steroid (dexamethasone) such cause lowered serum cortisol
cortisol <50 next morning is normal
- urine free cortisol, <250 is normal
why are random cortisols not as helpful
due to diurnal cortisol variation
what are the causes of cushings syndrome
pituitary (majority)
-cushings disease= pituitary adenoma
adenoma of adrenal- produces too much steroid
ectopic (neuroendocrine that produce ACTH)
- thymus
- lung
- pancreas
pseudo (can present with cushings)
- alcohol and depression
- steroid medication
what cause of cushings will have these test results:
ACTH of <300 that is suppressed by 50% with a high DDT
pituitary
what cause of cushings will have these test results:
ACTH of <1 that is not suppressed by a high DDT
adrenal
what cause of cushings will have these test results:
ACTH of >300 that is not suppressed by a high DDT
ectopic (ACTH may even rise)
how do you distinguish pituitary and non pituitary cushings
high dose DT - 2mg 6 hourly for 2 days
what would a CRH test show in pituitary disease (not in an adrenal adenoma)
50% increase in ACTH
20% increase in cortisol
what is the treatment for a pituitary adenoma
hypophysectomy
external radiotherapy if recurs
or bilateral adrenalectomy
what is the treatment for an adrenal adenoma
adrenalectomy
what is the treatment for an ectopic cause of cushings
surgery to remove source
or
bilateral adrenalectomy
what is the most usually ectopic cause of cushings
carcinoid tumour
what is the drug treatment for cushings
metyrapone- dont produce steroid hormone (if other treatment fail/ waiting for radiotherapy to work)
ketoconazole (hepatotoxic)
pasireotide
what are the results of pan hypopituitarism
anterior pituitary:
- lack of growth hormone: growth failure
- lack of TSH: hypothyroidism
- lack of LH/FSH: hypogonadism
- lack of prolactin: none known
posterior pituitary
-lack of ADH: diabetes insipidus
what can cause hypopituitarism
pituitary tumours (non functional or secreting)
secondary metastatic lesions (lung, breast)
local brain tumour (next to pituitary- astrocytoma, meningioma, glioma)
granulomatous diseases (TB, histiocytosis X, sarcoidosis)
vascular diseases (polyarteritis)
trauma (road accidents, skull fractures)
hypothalamic diseases (syphilis, menigitis)
iatrogenic, surgery
autoimmune- sheenan (post pregnancy)
infection (meningitis)
what are the symptoms of anterior hypothyroidism
menstrual irregularities infertility, impotence gynaecomastia (M) abdominal obesity (lack of thyroid) loss of facial hair (M) loss of axillary and pubic hair dry skin and hair hypothyroid faces growth retardation
what is the peripheral hormone for TSH
thyroxine (T4)
what tests are best at measuring the steroid axis
synacthen and ITT
in post menopausal women what should LH and FSH be like
be high - low would suggest pituitary disease
what is the replacement for hypopituitarism
thyroxine (100-150mcg/day) hydrocortisone (10-25mg/day) ADH desmopray (nasal) or tables GH (nightly) sex steroids (HRT, oest.prog pill for females, testosterone for males)
what are the benefits of growth hormone in adults
improves well being an QOL decreases abdo fat increases muscle mass, strength and stamina imporves cardiac function decreases cholesterol and increases LDL increases bone density given daily by SC injections
how can testosterone replacement be administered
IM injection every 3-4 weeks skin gel (testogel, tostran) prolonged IM injection 10-14 weeks oral tablets (hard as peptide so destroyed in stomach acid unless in capsule)
what are the risks of testosterone replacement
prostate enlargement (doesn’t cause prostate cancer) (monitor PR exam and PSA at start)
polycythaemia - increased haemoglobin in the blood
hepatitis (only oral tablets)
what are the causes of cranial diabetes insipidus
familial (DIDMOAD; DI, DM, optic atrophy, deaf)
acquired (idiopathic, trauma: road accidents, surgery, skull fracture)
rare: tumour, sarcoid, external irradiation, meningitis
describe the water deprivation test
check serum and urine osmolalities for 8 hours, and then 4h after giving IM DDAVP
if urine/serum osml ratio >2 then normal
(urine more concentrated) if less then DI
if improves after DDAVP then due to cranial DI (deficiency of DDVAP)
if not then nephrogenic
what is the treatment for DI
desmospray
desmopressin oral tablets
desmopression injection
does a baseline urine to serum osmolality >2 usually avoids the need for a water deprivation test
yes
is a 1mg overnight dexamethasone suppression test is the best screening test for Cushing’s syndrome
yes
