case 9 - endocrinology Flashcards
(52 cards)
what are adrenal hormones all derived from
cholesterol
what is DHEA
androstenedione - route for sex steroid precursors
what is the main glucocorticoid of the body
cortisol
what does over production in the glomerulosa mean
mineralocorticoid excess - Conn syndrome
what does over production in the fasiculata mean
glucocorticoid excess - Cushing syndrome
what does over production in the reticularis mean
excess sex steroid precursors +cortisol due to a tumour
what happens if there is primary underproduction
the primary: entire cortex is affected (Addison disease, TB/ HIV)
what happens if there is secondary underpriduction
Secondary; hypopituitarism; loss of ACTH I.e aldosterone secretion preserved
what happens if there is disordered production - what is the problem here with
Disordered production - problems with the enzymes
congenital adrenal hyperplasia - virtually never cancer
what is cushings syndrome
classically thought to be rare
Excessive, inappropriate endogenous cortisol secretion characterised clinically and biochemically by:
Features of glucocorticoid excess
Loss of circadian rhythm to cortisol secretion
Disruption of negative feedback loop
what are the symptom and signs of cushings syndrome
Moon face with purplish plethora
*Central obesity, buffalo hump
*Weight Gain
*Hypertension
*Depression/ psychosis
*Diabetes mellitus
*Hypogonadism
*Susceptibility to infection
*Malaise
*Osteoporosis
*Easy bruising
*Striae
*Proximal myopathy
*Poor wound healing
*Hirsuites
*Acne
Symptoms overlapping with PCOS
what can be thought of as antagonistic to insulin
cortisol - like glucagon, epinephrine and growth hormones
how does cortisol increase blood glucose levels
promotes gluconeogenesis
raises hepatic glucose output
inhibits glucose uptake by muscle and fat
what are the other effects of cortisol
lipolysis from adipose tissues
protein catabolism to release amino acids
how is glucocorticoid excess diagnosed
Loss of circadian rhythm
random cortisol is no use
Measure bedtime/nighttime serum or salivary cortisol levels
- Measure 24 hour urinary free cortisol
- If overactivity is suspected; try to suppress it
- measure cortisol after low dose of dexamethasone
- 1mg overnight or 0.5mg QID for 8 doses
- following 9am cortisol should be suppressed (less than 50nmol/L)
- Exclude pseudo-Cushing syndrome
clinical features of Cushing syndrome, which disappears when the underlying cause is resolved
Common causes alcohol, depression
Glucocorticoid excess / Cushing syndrome diagnosed
what are the two causes of Cushings syndrome
adrenal tumour. - ACTH undetectable
distinguishing between ACTH dependent causes
how do you distinguish between ACTH dependent causes
Low dose dexamethasone suppression test - diagnose Cushing Syndrome
Inferior petrosal sinus sampling
High-dose dexamethasone suppression test
localise Cushing syndrome
2mg QID (i.e 6 hourly) for 8 doses ending at midnight
Corticotrophin tumour: >50% suppression of following 9am cortical
Ectopic ACTH: <50% suppression of following 9am cortisol
For tumours - adrenalectomy
what is the medical treatment of Cushing Syndrome
untreated life expectancy <5 years
Medical
Block production of cortisol (metyrapone…ketoxonazole, mitotane)
pituitary tumours
Trans-sphenoidal hypophysectomy +/- radiotherapy
20-50% may not be permanently cured
May require bilateral adrenalectomy
ectopic ACTH
Usually palliative, surgery, DXT/chemotherapy
adrenal tumours
Adrenalectomy
what is hypoadrenalism
rare - 0.8 cases per 100,000
Primary causes
TB/AIDS
Addison disease / autoimmune (T1DM, thyroid disease, PA, vitiligo)
Lymphoma
Metastatic tumour
Intra-adrenal haemorrhage or infarction
Bilateral adrenalectomy
secondary hypoadrenalism comes from pituitary insufficiency
what are the features of hypoadrenalism
Clinical features:
Primary hypoadrenalism: lack of cortisol and aldosterone
*Non-specific
*Tiredness
*Weakness
*Nausea & vomiting
*GI disturbance
*Abdominal pain
*Weight loss
*Postural hypotension (supine and erect BP)
*Dizziness
*Fainting
*May present in circulatory failure (‘crisis’)
*Hypoglycaemia
what means primary hypoadrenalism
*Hypotensive, hyperkalaemic patient = PRIMARY HYPOADRENALISM
what is the diagnosis and treatment of hypoadrenalism
if under-activity is suspected; try to stimulate it
Short synacthen test
Give ACTH i.v./I.m. and measure cortisol 30 mins later
If less than 400nmol/L, it is inadequate
treat with hydrocortisone lifelong
10mg on waking, 5mg mid afternoon
Double in significant illness
steroid alert bracelet
Steroid card
May need mineralocorticoid replacement
Fludrocortisone
what is endocrine hypertension in the adrenal cortex due to
Conn syndrome
what is endocrine hypertension in the adrenal medulla due to
phaeocromocytoma
