Clinical Aspects of Adrenal Disorders Flashcards
What does each layer of the adrenal glands secrete?
Zone Glomerulosa- Aldosterone
Zone Faticulata- Cortisol
Zona Reticularis- Androgens
What can hypofunction of the adrenal glands be caused by?
- Primary adrenal insufficiency
- Addison’s disease
- Immune destruction
- Invasion
- Infiltration
- Infection
- Infarction
- Iatrogenic
- Adrenal enzyme defect
- Congenital adrenal hyperplasia (most commonly 21-hydroxylase deficiency)
- Addison’s disease
What enzyme most commonly causes adrenal enzyme defect?
21-hydrolase deficiency
What does adrenal enzyme defect cause?
Congenital adrenal hyperplasia
State the common autoantibodies responsible for Addisions disease
Positive adrenal autoantibodies to 21-hydroxylase
How is the adrenal cortex involved in Addison’s disease?
Lymphatic infiltrate of adrenal cortex
Addison’s disease is often associated with other autoimmune disease, what are some examples?
Thyroid disease
Type 1 diabetes mellitus
Premature ovarian failure
What are some common symptoms of primary adrenal failure?
What are some clues to a diagnosis of adrenal failure?
- Disproportion between severity of illness and circulatory collapse/hypotension/dehydration
- Unexplained hypoglycaemia
- Other endocrine features (hypothyroidism, body hair loss, amenorrhoea)
- Previous depression or weight loss
Investigations for Adrenal Insufficiency
Synacthen test (and basal ACTH)- synthetic ACTH given- +ve if cortisol does not increase
Routine bloods (U and Es, glucose, FBC)
Random cortisol (<450nmol/L)
MRI/CT for Adrenal/Pituitary tumours
Treatment for Primary Adrenal Insuffiency
Glucocorticoid replacement (replace cortisol):
- Hydrocortisone 20-30mg
- Prednisolone 7.5mg
- Dexamethasone 0.75mg
Minerocorticoid Replacement (aldosterone):
- Fludocrtisone 50-300mg
What are 3 important self-care rules for patients on steroids?
- Never miss steroid dose
- Double the hydrocortisone dose in the event on intercurrent illness (such as flu or UTI)
- If severe vomiting or diarrhoea call for help without delay
What are some causes of hypersecretion of adrenal glands?
- Cortex
-
Cushing’s syndrome (cortisol, androgens)
- Adenoma, carcinoma or bilateral hyperplasia
-
Conn’s syndrome (aldosterone)
- Adenoma or bilateral hyperplasia
-
Cushing’s syndrome (cortisol, androgens)
- Medulla
- Phaeochromocytoma
What does Cushing’s syndrome cause hypersecretion of?
Cortisol, androgens
What does Conn’s syndrome cause hypersecretion of?
Aldosterone
What are some causes of primary Cushing’s syndrome?
Pituitary Adenoma, carcinoma or bilateral hyperplasia
What are some causes of primary Conn’s syndrome?
Adenoma or bilateral hyperplasia
What is the clinical presentation of Cushing’s syndrome?
What are some ACTH dependent causes of Cushing’s syndrome?
- Pituitary tumour (Cushing’s disease)
- 75% of cases
- Ectopic ACTH secretion (such as lung carcinoid)
- 5% of cases
What are some ACTH indendent causes of Cushing’s syndrome?
Adrenal Tumour
Investigations for Cushings
1) 24hr Urinary free cortisol (12-135nmol/day)
2) Low Dose Dex test
3) High Dose Dex test (if low dose comes back abnormal)
Investigations for Conns Syndrome
- 1st Line: Aldosterone to renin ratio (Plasma Aldosterone:Plasma Renin Activity Ratio PA:PRA)
- 24Hr Urinary aldosterone (12 ug/day)
- CT MRI
- Serum Electrolytes (High Na, Low K)
- Blood gas- alkalosis
What does low PA low PRA potentially indicate
Congenital Adrenal Hyperplasia
What does high PA low PRA potentially indicate
Conns Syndrome
