Clinical abnormalities of glands Flashcards
(28 cards)
What is a primary hormone over/under secretion caused by?
A problem with the specific gland
What is a secondary hormone over/under secretion caused by?
a problem with the pituitary gland (no/too much hormone is produced to tell the specific gland to produce another hormone)
Can a tumour/nodules be present in the gland or pituitary without affecting hormone secretion?
Yes
Abnormalities in which three glands can be diagnosed simply with a static test?
Thyroid
Sex glands
Prolactin over-secretion
What is tested for in a static test for those with suspected primary hyperthyroidism? What levels? Why?
T3 and T4 will be elevated
TSH will be suppressed
Negative feedback form high levels of T3/T4 prevents the pituitary from producing more TSH
When are stimulation tests used?
To test for hormonal UNDER-SECRETION when static tests are not enough
When are suppression tests used?
To test for hormonal OVER-SECRETION when static tests are not enough
How is a stimulation test used to test for adrenal insufficiency?
ACTH is given, cortisol levels are expected to rise because the adrenal gland is stimulated by ACTH to secrete cortisol
What is the insulin stress test? What does it test for?
Insulin is given, which lowers the blood sugar. Low glucose levels cause a stressful situation for the body because glucose is needed for the brain to function, so hormone secretion e.g. cortisol, growth hormone, rises. If tis does not happen, there is a problem with the pituitary gland.
Why is glucagon stimulation sometimes used instead of the insulin stress test?
It is less sensitive, but is used in patients with heart problems etc. who may not be able to cope with the insulin stress test.
How is steroid production tested using a suppression test?
Exogenous steroids are given, which should switch off internal cortisol/steroid production through suppression of ACTH by negative feedback. If not, then the gland is producing too much steroid.
How is a suppression test used to test for GH production?
Glucose is given and GH secretion is tested. Glucose should switch off GH production.
what is gland over-secretion usually caused by?
Benign tumours
What can gland under-secretion be caused by?
Gland destruction due to;
- inflammation (including autoimmune conditions)
- infarction (obstruction of blood supply)
- tumours/nodules with normal hormone production that block secretions
- other
What is prolactin over secretion usually caused by?
A pituitary tumour secreting prolactin (prolactinoma)
Usually benign
What control is prolactin usually under?
Inhibitory
Dopamine is secreted by the hypothalamus to prevent prolactin secretion
What are the clinical presentations of prolactin over-secretion?
Galactorrhea (breast milk production)
Amenorrhoea
Headaches and visual field problems
Sexual dysfunction because less FSH and LH
How is prolactin over-secretion diagnosed?
Static test and MRI to confirm the tumour
What else can cause prolactin levels to mildly increase?
Sexual intercourse nipple stimulation stress drugs non-functioning pituitary tumour which compresses the hypothalamus and interferes with inhibitory effect
Do prolactinomas usually require surgery?
No, can usually be treated medically
What does growth hormone over secretion cause?
Excessive growth spurts, increased size of feet and hands, gigantism
In adults, skin, soft tissue and skeleton are effected giving an acromegalic face and wide hands/feet and increased sweating
How is GH over-secretion diagnosed?
Suppression tests; glucose is given followed by GH measurements at different time points.
Glucose should suppress GH production and plasma levels of the hormone should fall.
Imaging is needed to confirm the presence of a pituitary tumour
What is the treatment for GH over-secretion?
Surgical removal of tumour
Radiotherapy and medical therapy if not all the tumour is removed
What are the symptoms of cushing’s syndrome?
Causes growth arrest in children
Typical facial appearance is round (moon like), acne, excess hair.
Fat redistribution and truncal obesity with thin extremities
Thin skin, easy bruising, striae (stripes) on abdomen
