adrenal hormones Flashcards
Which hormone released from they hypothalamus regulates release of ACTH from the anterior pituitary?
Corticotropin releasing hormone (CRH)
Which glands does ACTH act on?
The adrenal glands
Which major hormones are secreted by the adrenal cortex?
mineralcorticoids (aldosterone), glucocortoids (cortisol),oestrogen, androgens
Which major hormones are secreted by the adrenal medulla?
Adrenaline, noradrenaline
What are the 3 layers of the adrenal cortex?
Zona glomerulosa, zona fasciculata, zona reticularis (superficial to deep)
Which zone of the adrenal cortex produces cortisol?
Zona fasciculata
What is the process of production of cortisol?
- ACTH binds to the Zona fasciculata in the adrenal cortex.
- Cholesterol is transported into cell mitochodnria and is converted to pregnenolone (steroid hormone precursor)
- Pregnenolone is converted to cortisol
What are the metabolic functions of cortisol?
Increases adipose breakdown to release fatty acids, increases muscle protein breakdown, increases gluconeogenesis and glycogenolysis in the liver increase blood glucose levels.
What are the non-metabolic effects of cortisol?
Increases blood pressure, suppresses the immune system appropriately
What is the pattern of cortisol secretion?
Secretion is cyclical, with levels highest in the morning. There is also pulsatile release in response to stress.
What are the negative feedback loops associated with cortisol?
cortisol has negative feedback to the hypothalamus and the anterior pituitary
What are the causes of Cushing’s Syndrome?
Cushing’s disease (ACTH secreting pituitary adenoma), Ectopic ACTH secreting tumor, Adrenal adenoma/carcinoma secreting cortisol. adrenal hyperplasia, excessive corticosteroid use
What type of tumor is most likely to become an ectopic ACTH secreting lesion?
Small cell bronchus carcinoma
What are the symptoms of Cushing’s syndrome?
Weight gain in face/upper back/abdomen, thin skin, striae, muscle weakness/wasting, fatigue, hypertension, hyperglycaemia, osteoporosis, depression/anxiety, irregular menstruation, hirsutism
What biochemical abnormalities are common in Cushing’s syndrome?
hypokalemia, hypernatremia, alkalosis
What are the results of a 24 urinary free cortisol test in Cushing’s syndrome?
Would expect high levels
What are the results of a low-dose dexamethasone suppression test in Cushing’s syndrome?
Cortisol levels usually will remain elevated, regardless of the cause of the Cushing’s syndrome
What are the results of a high-dose dexamethasone suppression test in Cushing’s syndrome?
Pituitary ACTH tumors will show cortisol suppression,
Ectopic ACTH tumors/adrenal tumors will not show cortisol supression at high doses as they are not affected by negative feedback.
What are the levels of plasma ACTH in Cushing’s syndrome?
High ACTH suggests pituitary/ectopic tumor secretion, while low ACTH suggest adrenal tumor
What are the non-pharmacological treatments for Cushing’s syndrome?
Surgical/radiation tumor removal from pituitary/ectopic/adrenals
What are the pharmacological treatments for Cushing’s syndrome?
Glucocorticoid receptor antagonists (mifepristone), steroidogenesis receptor antagonists
What are the causes of Addison’s disease?
Autoimmune adrenalitis, adrenal infecton (TB, HIV, fungal), adrenal caricinoma, congential adrenal hyperplasia
What is congenital adrenal hyperplasia?
A genetic condition that impairs the production of many adrenal hormones via an enzyme deficiency.
What are the symptoms of Addison’s disease?
Fatigue, weakness, weight loss, skin hyperpigmentation, hypotension, syncope, hypoglycaemia, nausea, abdominal pain, depression
