Endocrine - basic principles Flashcards
1
Q
Go over the thyroid axis
A
2
Q
Why are thyroid hormones of limited value in acutely unwell patients ?
A
- Euthyroid sick syndrome often seen in starvation, critical illness or patients in intensive care unit.
- Characterised by low free hormone levels and inappropriate low/normal TSH but the thyroid gland does not appear to be dysfunctional
3
Q
Go over the hypothalmic pituitary adrenal axis
A
4
Q
What is prolactin secreted by ?
A
Lactotroph cells of the anterior pituitary
5
Q
What are some of the problems you can have with cortisol secretion ?
A
Cortisol deficiency = adrenal insufficiency due to:
- Primary adrenal failure (e.g. Addison’s disease)
- Pituitary disease
Cortisol excess = Cushing’s syndrome due to:
- Pituitary origin
- Adrenal origin
- Ectopic ACTH (exogenous steroids)
6
Q
What is the idea of dynamic testing done to assess hormone secretion/deficiency ?
A
- Hormone excess – suppression test
- Hormone deficiency – stimulation test
7
Q
What dynamic tests are done to assess cortisol excess or cortisol insufficiency ?
A
- Stimulation test – Synacthen Test
- Suppression test – Dexamethasone suppression test
8
Q
How is cushings syndrome diagnosed ?
A
Low dose dexamethasone suppression test:
- Failure to suppress = Cushing’s syndrome
