HPA axis Flashcards by S G

What are the 3 layers of the adrenal gland?

Capsule
Cortex
Medulla

How well did you know this?

Not at all

Perfectly

What are the layers of the adrenal cortex?

Zona glomerulosa
Zona fasciculata
Zona reticularis

How well did you know this?

Not at all

Perfectly

What is produed in the zona glomerulosa?

Mineralocorticoids- aldosterone/ progesterone

How well did you know this?

Not at all

Perfectly

What is produced in the zona fasciculata?

Corticosteroids - cortisold
small amounts of androgens

How well did you know this?

Not at all

Perfectly

What is produced in the zona reticularis?

Androgens eg DHEA and small amount of corticosteroids

How well did you know this?

Not at all

Perfectly

What is the venous and arterial supply of the adrenal glands?

Venous:
R: inf. vena cava
L: l renal vein

Arterial:
Sup, mid, inf adrenal artery

How well did you know this?

Not at all

Perfectly

What is produced in the adrenal medulla?

Chromaffin cells produce catecholamines, epinephrine, norepinephrine

How well did you know this?

Not at all

Perfectly

Describe the HPA axis

Hypothalamus -> CRH (corticotropin releasing hormone)
Ant. pit -> ACTH (adrenocorticotropin hormone)
Cortex of adrenal gland -> glucocorticoids (androgens and cortisol)

How well did you know this?

Not at all

Perfectly

What are the normal physiological actions of cortisol?

Gluconeogenesis
Lipolysis in adipose tissue
Protein and fat metabolism
Anti-inflam
Immunosupression

How well did you know this?

Not at all

Perfectly

What are the actions of glucocorticoids?

affect carc, fat, protein metabolism `

How well did you know this?

Not at all

Perfectly

What are the actions of mineralocorticoids?

control sodium and potassium balance (aldosterone)

How well did you know this?

Not at all

Perfectly

What is the action of CRF?

Corticotropin releasing factor acts on ant pit -> ACTH to act on adrenal cortex to release androens and cortisol

How well did you know this?

Not at all

Perfectly

What type of hormones does the adrenal cortex produce

steroid hormones

How well did you know this?

Not at all

Perfectly

What is Cushing’s syndrome?

Abnormal persistent elevated glucocorticoid levels with loss of circadian cortisol secretion and loss of normal negative feedback

How well did you know this?

Not at all

Perfectly

What is Cushing’s disease?

Pituitary adenoma causing excessive ACTH secretion causing bilateral adrenal hyperplasia causing excessive cortisol production

How well did you know this?

Not at all

Perfectly

What are the ACTH dependent causes of cushings syndrome?

Cushing’s disease - pit adenoma
Ectopic ACTH production eg small cell lung cancer and carcinoids

How well did you know this?

Not at all

Perfectly

What are the ACTH independent causes of Cushing’s syndrome?

Adrenal carcinoma
Iatrogenic - steroid use

How well did you know this?

Not at all

Perfectly

What are the signs for Cushing’s syndrome?

Round moon face
Central obesity
Back buffalo hump
Purple abdo striae
Hyperglycaemia/ hypertension/ osteoporosis
Thin skin

How well did you know this?

Not at all

Perfectly

What are the symptoms for Cushing’s syndrome?

Weight gain
Acne
Peripheral weakness
Mood change- irritable/ depression/ psychosis
Gonadal dysfunction- erectile dysfunction/ irregular periods

How well did you know this?

Not at all

Perfectly

What is the men to women prevalence of cushing disease?

equal

What age do people usually present with Cushing’s?

30-50 yrs

What is the main investigation for Cushing syndrome?

dexamethasone suppression test

How is dexamethasone used to diagnose Cushings

Acts as glucocorticoid steroid to suppress ACTH production
Sees if cortisol production is reduced

What are the results for the first line dexamethasone test for Cushings?

Suppressed ACTH and high cortisol with low dose (1mg) of dexa.
Given at night, measured in the morning

What are the results for the second dexamethasone test for cushing's?

Cushing's disease = suppressed ACTH and cortisol Ectopic ACTH = high ACTH and cortisol Adrenal adenoma = suppressed ACTH and high cortisol

What is the treatment for iatrogenic Cushing's syndrome ?

stop medication

What is the treatment for Cushing's disease

Pituitary adenoma removal

What is the treatment for Cushing's syndrome caused by ectopic ACTH?

Surgery

What is the treatment for Cushing's syndrome caused by adrenal adenoma?

Adrenalectomy (nelsons syndrome as a complication)

What are the conditions for the dexamethasone suppression test?

Overnight 12am given then 8am measurement

What is primary adrenal insufficiency?

Destruction of the adrenal cortex resulting in deficiency in mineralocorticoids, glucocorticoids and androgens

What is Addison's disease?

Primary adrenal insufficiency caused by autoimmune destruction of the adrenal cortex resulting in deficiency of mineralocorticoids, glucocorticoids and androgens

Describe the pathophysiology of Addison's disease

Autoimmune destruction of adrenal cortex by 21-hydroxylase adrenal autoantibodies

What are the ACTH levels in Addisons and why and what symptom does this cause?

High due to low cortisol levels which results in negative feedback to pit gland causes hyperpigmentation

Describe the epidemiology of Addison's

Rare- 0.8/100,000 More common in women

What is the main cause of primary adrenal insufficiency in the UK

Addisons disease

What is the main cause of primary adrenal insufficiency worldwide?

Describe the clinical presentation of Addison's disease

Fatigue Tanned Hyperpigmentation- palmar, sun-exposed areas, waist GI: wt loss, abdo pain, nausea, vomiting, loss appetite CVS: postural hypotension, hypoglycaemia MSK: joint pain, muscle cramps Depressed/ anxious/ psychosis Tanned, Tearful, Tired, Toned,

What are the investigations and results for Addison's disease?

ACTH stimulation test: low cortisol U&E: High K+ and low Na+ (lack aldosterone) Serum ACTH: High ACTH and low cortisol= primary Low ACTH and cortisol = secondary 21-hydroxylase adrenal autoantibodies positive

What is the ACTH stimulation test and what is it used for?

Used to diagnose Addison's disease Measure baseline cortisol Give ACTH and measure cortisol 30 min after Addisons= low cortisol (adrenal destruction)

What is the managment of Addison's?

Oral hydrocortisone to replace steroids Fludrocorticosone to replace aldosterone

What are the Na and K ion levels for Addison's disease and why?

Low Na+ and high K+ due to lack of aldosterone

What are the complications of Addison's disease?

Adrenal crisis - life threatening

What are the symptoms of an adrenal crisis?

Reduced conciousness Hypoglycaemia, hypotension

What is the management for an adrenal crisis?

Immediate treatment IV fluids Steroids Glucose Intensive monitoring

What is secondary adrenal insufficiency?

Lack of ACTH production from the pit gland causing deficiency in cortisol

What is the common cause in secondary adrenal insufficiency?

Iatrogenic- long term steroid use disturbs the pit. adrenal axis

How is primary adrenal insufficiency different to hypothalamic-pituitary disease?

Deficiency in mineralocorticoids which aren't controlled by the pituitary