Flashcards in Diagnosis of Adrenal Disorders Deck (38):
1
What is the structure that is common to all steroids?
4 rings
2
What is cortisol also know as?
Hydrocortisone
3
What is cortisone?
Very weak glucocorticoid
Biologically inactive metabolite of cortisol
4
What happens to cortisone after administration to a patient?
Metabolised to cortisol in liver
5
What is the major glucocorticoid?
Cortisol
6
What is the action of glucocorticoids?
Stimulation of gluconeogenesis in liver
Mobilisation of amino acids in muscle
Stimulation of lipolysis in adipose tissues
Immunosuppression
7
What does too much cortisol lead to?
Weight gain
Wasting of
- Muscle
- Skin
- Bone
Hyperglycaemia
Salt retention > hypertension
Inhibition of linear growth
8
What can cause ACTH-dependent hypercortisolism?
Pituitary adenoma = Cushing's disease
Ectopic ACTH syndrome
9
What can cause ACTH-independent hypercortisolism = Cushing's syndrome?
Adrenal adenoma/carcinoma
ACTH-independent nodular hyperplasia
Administration of glucocorticoids
10
What is the most common cause of Cushing's syndrome?
Administration of glucocorticoids
11
What happens in abnormal states when you deliberately stimulate/suppress the hormone to test for its function?
Hormone won't rise into normal range when you stimulate it
Won't fall into normal range if you suppress it
12
What is a 24 hour urine assay useful for?
Tell you about variation throughout day
13
How do you investigate suspected Cushing's syndrome?
24 hour urine free cortisol
Check diurnal variation: serum cortisol and plasma ACTH
at
- 8 am
- 12 am
Check negative feedback loop working: dexamethasone suppression test
Cranial MRI/adrenal CT as indicated
14
What is dexamethasone?
Very powerful glucocorticoid
15
What happens when someone is given dexamethasone?
Should decreased ACTH and cortisol
16
What does it mean if ACTH and cortisol don't decrease when dexamethasone is given?
Something wrong with pituitary
17
What does not enough cortisol cause?
Can't cope with new stress; eg: infection
- Much sicker than they should be
GI symptoms
- Anorexia
- Nausea
- Vomiting
- Diarrhoea
- Weight loss
Salt wasting > low BP
Darkening of skin if ACTH secretion stimulated
Muscle weakness
- Skeletal
- Cardiac
18
What are the possible causes of adrenocortical insufficiency?
Genetic
- Enzyme defect in cortisol biosynthesis
- Metabolic defect = adrenoleukodystrophy
Autoimmne adrenal destruction
Infectious disease
- Adrenal destruction by TB
19
What is the most common cause of Addison's disease in Australia?
Autoimmune destruction of adrenal cortex
20
What are the clinical findings for Addison's disease?
Salt-wasting state > low Na and high K
21
How do you treat Addison's disease?
Cortisol
Fludrocortisone
22
Where does Addisonian pigmentation commonly occur?
Knuckles of hands
Knees
Gums and oral mucosa
General pigmentation
23
What happens when there is an excess of adrenal androgens?
Premature pubic hair
Hirsutism
Acne
Enlargement of penis/clitoris in child
Behavioural changes
Linear growth spurt
Rapid epiphyseal fusion in child
Muscular habitus
Deepening of voice
24
What is the cause of congenital adrenal hyperplasia (CAH) in 90% of cases?
21-hydroxylase deficiency
25
What is the inheritance pattern of CAH?
Autosomal recessive
26
What is the pathophysiology of CAH?
Variable impairment of cortisol and aldosterone synthesis > ACTH stimulation > adrenal hyperplasia > increased androgen > virilisation
27
What are the three different presentations of CAH in females?
Exposed to high levels of androgens in utero > infant with ambiguous genitalia
In utero androgens not that high > happens more slowly > premature pubic hair and enlarged clitoris
Adolescent hirsutism and acne
28
What are the presentations of CAH in males?
Adrenal crisis in baby aged 2-3 weeks
Premature sexual development at age 2-3 years
29
Why is there a decrease in oestrogen in CAH?
Made from testosterone and aromatase very tightly regulated
Do have slightly elevated levels
30
What is the most commonly used steroid treatment?
Prednisolone
31
What type of steroid is fludrocortisone?
Mineralocorticoid
32
What regulates aldosterone secretion?
Increase K in ECF
Angiotensin II
33
What are the actions of aldosterone?
Increased resorption of Na
Increased resorption of water
Increased excretion of K from kidney distal tubule
34
What does excess aldosterone (Conn's syndrome) cause?
Salt retention > hypertension
Hypokalaemia > weakness
Low renin
35
What does a deficiency in aldosterone cause?
Dehydration
Salt depletion
Postural hypotension
Hyperkalaemia > cardiac arrhythmias
36
What are possible causes of Conn's syndrome?
Adrenocortical tumour secreting aldosterone
37
What is the treatment for Conn's syndrome?
Surgery
38