L9 HPA axis

Question 1

Effects of glucocorticoids?

Answer 1

maintain homeostasis during stress
eg - anxiety, infection, haemorrhage
anti-inflammatory 
energy balance/metabolism
formation of bone/cartilage
regulation of BP 
cognition

Question 2

ULTRADIAN RHYTHM

Answer 2

Pulsatility’ of hormone release
anultradian rhythmis a recurrent period or cycle repeated throughout a 24-hour day. In contrast, circadianrhythmscomplete one cycle daily

Question 3

11-Beta-HSD enzymes

Answer 3

tissue specificity - gating of GC access to nuclear receptors

Question 4

Cushings syndrome

Answer 4

too much cortisol
weight gain 
central obesity 
hypertension 
insulin resistance
osteoporosis 
the excess cortisol could be caused by pit adenoma ACTH secreting cells 
or adrenal tumour - adenoma 
ectopic ACTH - carcinoid
Iatrogenic - steroid treatment

Question 5

clinical features of cushings syndrome

Answer 5

Central obesity with thin arms & legs
Fat deposition over upper back (‘buffalo hump’)
Rounded ‘moon’ face
Thin skin with easy bruising, pigmented striae
Hirsutism

Hypertension
Diabetes
Psychiatric manifestations
Osteoporosis

Question 6

what is Addisons disease

Answer 6

too little cortisol 
body wastage
gradually ill 
slight pain is referred to stomach
vomiting
skin discolouration - tanned

Question 7

Pathogenesis of addisons disease

Answer 7

primarily adrenal insufficiency

iatrogenic - patients on high dose, long term steroids which is suddenly stopped at a time of stress

Question 8

clinical features of addisons disease

Answer 8

malaise, weak, weight loss, increased skin pigmentation,

hypotension, hypoglycaemia

Question 9

Type 1 autoimmune polyendocrine syndrome

Answer 9

rare
infancy onset
AIRE gene
common phenotype - addisons, hypoparathyroidism, candidiasis

Question 10

Type 2 autoimmune polyendocrine syndrome

Answer 10

commoner but still rare
infancy to adulthood
polygenic
common phenotype - addisons, T1D, autoimmune thyroid disease

Question 11

How can you assess the HPAA?

Answer 11

Basal - blood -timing circadian rhythm (cortisol, ACTH), urine 24 hour collection - area under curve (cortisol) saliva - no timing(cortisol)
dynamic tests -
stimulated - ACTH, CRH
suppressed - dexamethasone

Question 12

Too much cortisol assessments

Answer 12

24 hour urinary free cortisol
measure area under curve
midnight cortisol - blood saliva
9am ACTH with paired cortisol

Question 13

Too little cortisol

Answer 13

9am cortisol
synACTHen test -adrenal response to ACTH
insulin tolerance test - response to hypoglycemic stress
U+E in addisons disease
sodium low pottasium high due to mineralocorticoid deficiency
can measure renin and aldo conc - aldo will be low and renin high
reduced glucose

Question 14

Imaging HPAA

Answer 14

Once you identify a patient has cushings consider
CXR
MRI pituitary
CT adrenals

Question 15

Management of cushings

Answer 15

surgical depending on cause
transphenoidal adenectomy
adrenalectomy
pituitary radiotherapy

Question 16

Management of addisons disease?

Answer 16

steroid hormone replacement therapy - glucocorticoid

Patients with primary adrenal insufficiency also need mineralocorticoid replacement therapy (fludrocortisone).
Patients with secondary adrenal insufficiency will often be taking other hormone replacement therapy (do not need fludrocortisone).