Adrenal gland: Addison's disease, Addisonian crisis, Cushing's syndrome Flashcards
Define addison’s disease?
Also known as primary adrenal insufficiency.
Refers to damaged adrenal glands (adrenal cortex) that secrete less cortisol and aldosterone.
Causes of addison’s disease?
- autoimmune
- tuberculosis
- adrenal metastases
- congenital adrenal hyperplasia
Presentation of addison’s disease?
- Fatigue, muscle weakness -hyponatremia, renal sodium wasting
- Abdominal pain, anorexia, nausea, vomiting -hyperkalemia
- hypotension (postural -with a drop of >20mmHg when standing) -hyponatremia
- hypoglycemia -acidosis
- hyperpigmentation in sun exposed areas -bronze pigmentation (ACTH stimulates melanocytes to produce melanin)
- Muscle cramps
- Dizziness and fainting
- Thirst and craving salt
- Weight loss
- Depression
- Reduced libido
- Amenorrhea
IVx for addison’s disease?
Serum cortisol level
-obtain early morning sample as cortisol is high at this point.
U&Es
-low sodium, high potassium, high creatinine, high urea
Blood glucose
-hypoglycaemia
Hypercalcemia
FBC
-anaemia, lymphocytosis
LFTs
-raised ALT, AST
TFTs
-raised TSH
SynthACTHen test (ACTH stimulation test)
What is SynthACTHen test?
- Tests for adrenal insufficiency.
- The test involves giving a dose of Synacthen, which is synthetic ACTH.
The blood cortisol is checked before, 30, and 60 mins after the
dose. - The synthetic ACTH will stimulate healthy adrenal glands to
produce cortisol. The cortisol level should at least double. - So if cortisol is still low and less than double, then it indicates either:
- Primary adrenal insufficiency (Addison’s disease)
- Very significant adrenal atrophy after a prolonged absence of ACTH in secondary adrenal insufficiency
Management of addison’s disease?
Hydrocortisone (a glucocorticoid) -replaces cortisol (if low).
Fludrocortisone (a mineralocorticoid) -replace aldosterone (if low).
Pts are given a steroid card, ID tag and emergency letter to alert emergency services that they depend on steroids for life.
Doses are doubled during an acute illness to match the normal steroid response to illness.
Close contacts are taught how to administer IM hydrocortisone in an emergency. It is crucial to avoid Addisonian crisis.
Define addisonian crisis?
refers to an acute presentation of severe adrenal insufficiency where the absence of steroid hormones leads to a life-threatening emergency.
Causes of addisonian crisis?
- increased dose of steroids not taken at times of stress/infection
- abrupt withdrawal of steroids
- can be triggered by trauma or infection
Presentation of addisonian crisis?
- Shock (postural hypotension, tachycardia)
- abdominal pain
- n+v
- severe fatigue
- Weak, confused, coma
- Hypoglycaemia
- Hyponatraemia
- Hyperkalaemia
Management of addisonian crisis?
- ABCDE approach to initial assessment and arrange transfer to hospital
- Intravenous hydrocortisone (the initial dose is 100mg, followed by an infusion or 6 hourly doses)
- IV fluids
- Blood glucose -correct hypoglycaemia (e.g., IV dextrose)
- Careful monitoring of electrolytes and fluid balance
- If infection -septic 6 -IV antiobiotics
Define Cushing’s syndrome?
refers to excess glucocorticoid and loss of normal feedback loop (circadian rhythm of cortisol secretion).
Define Cushing’s disease?
refers to a pituitary adenoma secreting excessive adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to release excessive cortisol.
Causes of Cushing’s syndrome?
Can be divided into ACTH-dependent and ACTH-independent.
ACTH-independent:
- adrenal adenomas/carcinomas (produce excess cortisol independently of ACTH stimulation)
ACTH-dependent disease:
- pituitary tumor (Cushing’s disease)
- ectopic ACTH-producing tumors (e.g. lung carcinoids, thymic carcinoids)
Presentation of Cushing’s syndrome?
- Weight gain
- Gonadal (reproductive organs) dysfunction -oligomenorrhea, infertility, decreased libido, hirsutism, erectile dysfunction
- Mood change -emotional lability, anxiety, depression
- Proximal muscle weakness
- Thirst
- Polyuria
- hypotension
- hypokalaemia
IVx for Cushing’s syndrome?
- high cortisol levels
- dexamethasone suppression test
- FBC -(high WBC count)
- U&Es (low potassium if an adrenal adenoma is also secreting aldosterone)
- MRI -pituitary adenoma
- CT chest -small cell lung cancer
- CT abdome -adrenal tumours
What is dexamethasone suppression test?
Used to diagnose Cushing’s syndrome.
Dexamethasone causes negative feedback on hypothalamus, reducing the release of corticotropin-releasing hormone (CRH). As a result, ACTH is reduced too.
Lower CRH and ACTH level results in low cortisol.
Lack of cortisol suppression in response to dexamethasone = Cushing’s syndrome
Suppressed cortisol = normal response
Types of dexamethasone suppression test?
Low-dose overnight test(screening test to exclude Cushing’s syndrome)
Low-dose 48-hour test (if suspecting Cushing’s syndrome)
High-dose 48-hour test (used to determine the cause in pts with confirmed Cushing’s syndrome)
- High dose = enough to suppress cortisol in Cushing’s syndrome caused by pituitary adenoma, but NOT adrenal adenoma or ectopic ACTH.
ACTHissuppresseddue tonegative feedbackon the pituitary whenexcess cortisolcomes from anadrenal tumour(or endogenous steroids). It is high when produced by apituitary tumourorectopic ACTH(e.g., small cell lung cancer).
Management of Cushing’s syndrome?
Cushing’s disease:
- surgical removal of pituitary adenoma +/-bilateral adrenalectomy, radiotherapy.
Adrenal adenoma
- unilateral adrenalectomy
Adrenal carcinoma
- adrenalectomy, radiotherapy, chemotherapy
Ectopic ACTH
- surgical removal if tumour is located, radiotherapy, chemotherapy
- ketoconazole (high dose) is an anti-fungal drug that inhibits adrenal steroid synthesis
Where surgical removal of the cause is not possible, another option is bilateral adrenalectomy and life-long steroid replacement therapy.
