L32 Endocrine pathology Flashcards
(20 cards)
what is a static test and what can it be used for?
a test to check levels and diagnose abnormalities eg of thyroid (T3, T4 + TSH) and sex glands
what is a stimulation test and what can it be used for?
it is used when static test is not enough. the test includes stimulation of secretion of a particular hormone for suspected under-secretion
EG injecting ACTH to see whether corticol is secreted from the adrenals (synacthen test)
or glucagon stimulation and insulin stress test for pituitary failure (tests for ACTH and GH response)
a failed test indictes gland failure
what is a suppression test and what can it be used for?
test for suspected over-secretion. the test involves injecting a steroid and testing for endogenous steroid production (external steroids should switch off internal steroid production)
eg giving glucose and testing GH secr (glucose switches off GH secr normally)
how can you tell whether it is primary or secondary hypo or hyperthyroidism?
is T3 and T4 are high and TSH low = primary hyperthyroidism (issue with thyroid gland)
if low T4 but high TSH then primary hypothyroidism
if high T4 and high TSH then secondary hyperthyroidism (problem with pituitary gland)
if low T4 and low TSH = secondary hypothyroidism
hoe does prolactin over-secretion happen and what are the clinical presentations? how is it diagnosed and treated?
Usually due to a pituitary tumour secreting prolactin (prolactinoma)
Clinical presentation:
- Galactorrhoea (breast milk production)
- Amenorrhoea in women and sexual dysfunction in men (WHY?)
- Headaches and visual field problems in large tumours
diagnosed by pituitary MRI
prolactinomas (over-secretory pituitary tumour) can be treated medically
apart from a prolactinoma, why else might prolactin levels be high?
A tumour between pituitary and hypothalamus can stop the hypothalamus interaction and inhibition function, leading to increased prolactin. So high prolactin does not always mean cancer of prolactin gland, could be a tumour affecting hypothalamus instead.
what might mildly raise prolactin levels?
Sexual intercourse
Nipple stimulation
Stress
Large number of drugs (including antipsychotics and antidepressants)
Non-functioning pituitary tumour (compressing the hypothalamus and interfering with the inhibitory effect on prolactin secretion)
does prolactin over-secretion associated with increased libido in med?
no - excess prolactin usually supressed male hormones, leading to a decrease in libido
how does an excess of growth hormone affect childhood/adolescents and in adults?
In childhood or adolescent growth hormone excess results in:
Excessive growth spurt and increased size of feet and hands
If left untreated growth hormone excess leads to gigantism, the most serious consequence of the disease
In adults, growth hormone excess affects the skin, soft tissue and skeleton:
Acromegalic face
Wide and large hands/feet
Increased sweating (common complaint)
how might a tumour of the pituitary glad result in visual field defects?
the tumour pressed on the optic chiasm, the crossing of the left and right optic nerves
is a static test enough to diagnose prolactin excess excess?
yes
is a static test enough to diagnose Growth hormone or cortisol excess? how is excess growth hormone tested?
no, a suppression test is necessary.
glucose is given, followed by GH measurements at different time points
normally, glucose suppresses GH production and hence plasma levels of hormones fall but not in those with over-secretion
how do you confirm presence of a pituitary tumour?
imaging eg MRI
how is a pituitary tumour treated?
Surgical removal of the tumour
Radiotherapy and medical therapy may also be needed as surgery does not always remove the whole tumour
how many does cushing’s syndrome affect and what may it be caused by?
affects around 1-2 per 100,000
May be due to:
Pituitary secreting ACTH tumour (Cushing’s disease)
Adrenal tumours secreting cortisol
Cancers producing ACTH (or a hormone which is similar to and acts like ACTH) (such as lung cancers)
what are the clinical presentations of cushing’s syndrome?
growth arrest in children
FACE
round (moon-like)
acne
hirsutism (male like hair)
FAT REDISTRIBUTION
truncal obesity
thin extremities
SKIN ABNORMALITIES
thin skin and easy bruising
striae on abdomen
what other clinical complications can occur with cushing’s syndrome?
hypertension
diabetes mellitus
high risk of infection
poor wound healing
how do you test for over-secretion of cortisol?
Static tests are not enough and suppression tests are required.
Dexamethasone suppression test is used to confirm the failure to suppress endogenous cortisol production.
How do you differentiate between adrenal and pituitary Cushing’s?
With pituitary dependent disease both adrenal glands are being over stimulated so they should both be symmetrical in size and shape and most likely enlarged.
what are the treatments of pituitary, adrenal and cancer-related cushing’s syndrome?
Pituitary and adrenal:
Surgery
Radiotherapy and/or medical treatment may also be required in pituitary disease
Cancer related
Treat original cancer
