Endocrine Flashcards
What is adrenal insufficiency?
the adrenal glands do not produce enough steroid hormones, particularly cortisol and aldosterone.
Steroids are essential for life = life-threatening unless the hormones are replaced.
What is Addison’s disease?
PRIMARY ADRENAL INSUFFICIENCY
specific condition where the adrenal glands have been damaged, resulting in a reduction in the secretion of cortisol and aldosterone
Most common cause of Addison’s disease
autoimmune
what is secondary adrenal insufficiency?
inadequate ACTH stimulating the adrenal glands, resulting in low cortisol release
What is ACTH
Adrenocorticotrophic hormone
secreted by the pituitary gland
causes of secondary adrenal insufficiency
damage to pituitary gland:
- pituitary tumour
- infection
- loss of blood flow
- radiotherapy
- Sheehan’s syndrome = massive blood loss in childbirth that leads to necrosis of the pituitary gland
what is tertiary adrenal insufficiency?
inadequate CRH release by the hypothalamus
what is CRH
Corticotrophin releasing hormone, released by the hypothalamus
Describe the HPA axis
hypothalamic-pituitary-adrenal axis:
- hypothalamus releases corticotrophin releasing hormone
- causing anterior pituitary to release adrenocorticotrophic hormone
- causing the adrenal cortex in the adrenal glands to release cortisol
causes of tertiary adrenal insufficiency
long term oral steroids - suppress the hypothalamus
This is why you shouldn’t suddenly withdraw exogenous steroids - hypothalamus is suppressed so no endogenous steroids will be produced
symptoms of adrenal insufficiency
Fatigue Nausea Cramps Abdominal pain Reduced libido
Signs of adrenal insufficiency
Bronze hyperpigmentation to skin (ACTH stimulates melanocytes to produce melanin)
Hypotension (particularly postural hypotension)
Ix for adrenal insufficiency
Hyponatraemia
Hyperkalaemia
Early morning cortisol - often falsely normal
Short synacthen test = FOR DIAGNOSIS
ACTH
- High in primary adrenal insufficiency
- low in secondary adrenal insufficiency
Adrenal cortex antibodies & 21-hydroxylase antibodies - in autoimmune adrenal insufficiency
CT/MRI adrenals
MRI pituitary
What is the short synacthen test?
For diagnosing adrenal insufficiency
Give synacthen (synthetic ACTH) blood cortisol measured at baseline, 30 mins and 60 mins Synthetic ATCH wil stimulate healthy adrenal glands & the cortisol should at least double
Failure of cortisol to at least double = primary adrenal insufficiency (Addison’s)
tx of adrenal insuffiency
hydrocortisone to replace cortisol
fludrocortisone to replace adolesterone
Patients need: steroid card & double doses on sick days (don’t STOP)
What is an addisonian crisis?
Adrenal crisis
Acute presentation of severe Addison’s disease
The absence of steroid hormones leads to a life threatening presentation
Symptoms of addisonian crisis
Reduced consciousness
Hypotension
Hypoglycaemia, hyponatraemia, hyperkaemia
Patients can be very unwell
what triggers an addisonian crisis
infection
trauma
other acute illness
sudden steroid withdrawal
mx of addisonian crisis
Intensive monitoring IV hydrocortisone IV fluid resuscitation Correct hypoglycaemia Careful monitoring of electrolytes
What is cushings syndrome?
the signs and symptoms that develop after prolonged abnormal elevation of cortisol.
What is Cushings disease?
the specific condition where a pituitary adenoma (tumour) secretes excessive ACTH.
Difference between cushings syndrome and cushings disease
Cushings disease causes cushings syndrome
but cushings syndrome isn’t always caused by cushings disease
symptoms of cushings syndrome
round 'moon' face central obesity abdo striae buffalo hump - fat pad on upper back proximal limb muscle wasting
HTN cardiac hypertrophy hyperglycaemia (T2DM) depression insomnia
osteoporosis
easy bruising
poor skin healing
causes of cushings syndrome
exogenous steroids
cushings disease = pituitary adenoma releasing excessive ACTH
adrenal adenoma
paraneoplastic cushings - ACTH released from small cell lung cancer